pod/perlcompile.pod Info on using the Compiler suite
pod/perldata.pod Data structure info
pod/perldbmfilter.pod Info about DBM Filters
+pod/perldebguts.pod Debugger guts info
pod/perldebug.pod Debugger info
pod/perldelta.pod Changes since last version
pod/perldiag.pod Diagnostic info
# Debugger for Perl 5.00x; perl5db.pl patch level:
-$VERSION = 1.06;
+$VERSION = 1.07;
$header = "perl5db.pl version $VERSION";
-# Enhanced by ilya@math.ohio-state.edu (Ilya Zakharevich)
-# Latest version available: ftp://ftp.math.ohio-state.edu/pub/users/ilya/perl
-
-# modified Perl debugger, to be run from Emacs in perldb-mode
-# Ray Lischner (uunet!mntgfx!lisch) as of 5 Nov 1990
-# Johan Vromans -- upgrade to 4.0 pl 10
-# Ilya Zakharevich -- patches after 5.001 (and some before ;-)
-
#
# This file is automatically included if you do perl -d.
# It's probably not useful to include this yourself.
# reset LineInfo to something "interactive"!)
#
##################################################################
+
+# Enhanced by ilya@math.ohio-state.edu (Ilya Zakharevich)
+# Latest version available: ftp://ftp.math.ohio-state.edu/pub/users/ilya/perl
+
+# modified Perl debugger, to be run from Emacs in perldb-mode
+# Ray Lischner (uunet!mntgfx!lisch) as of 5 Nov 1990
+# Johan Vromans -- upgrade to 4.0 pl 10
+# Ilya Zakharevich -- patches after 5.001 (and some before ;-)
+
# Changelog:
# A lot of things changed after 0.94. First of all, core now informs
# `b load' strips trailing whitespace.
# completion ignores leading `|'; takes into account current package
# when completing a subroutine name (same for `l').
+# Changes: 1.07: Many fixed by tchrist 13-March-2000
+# BUG FIXES:
+# + Added bare mimimal security checks on perldb rc files, plus
+# comments on what else is needed.
+# + Fixed the ornaments that made "|h" completely unusable.
+# They are not used in print_help if they will hurt. Strip pod
+# if we're paging to less.
+# + Fixed mis-formatting of help messages caused by ornaments
+# to restore Larry's original formatting.
+# + Fixed many other formatting errors. The code is still suboptimal,
+# and needs a lot of work at restructuing. It's also misindented
+# in many places.
+# + Fixed bug where trying to look at an option like your pager
+# shows "1".
+# + Fixed some $? processing. Note: if you use csh or tcsh, you will
+# lose. You should consider shell escapes not using their shell,
+# or else not caring about detailed status. This should really be
+# unified into one place, too.
+# + Fixed bug where invisible trailing whitespace on commands hoses you,
+# tricking Perl into thinking you wern't calling a debugger command!
+# + Fixed bug where leading whitespace on commands hoses you. (One
+# suggests a leading semicolon or any other irrelevant non-whitespace
+# to indicate literal Perl code.)
+# + Fixed bugs that ate warnings due to wrong selected handle.
+# + Fixed a precedence bug on signal stuff.
+# + Fixed some unseemly wording.
+# + Fixed bug in help command trying to call perl method code.
+# + Fixed to call dumpvar from exception handler. SIGPIPE killed us.
+# ENHANCEMENTS:
+# + Added some comments. This code is still nasty spaghetti.
+# + Added message if you clear your pre/post command stacks which was
+# very easy to do if you just typed a bare >, <, or {. (A command
+# without an argument should *never* be a destructive action; this
+# API is fundamentally screwed up; likewise option setting, which
+# is equally buggered.)
+# + Added command stack dump on argument of "?" for >, <, or {.
+# + Added a semi-built-in doc viewer command that calls man with the
+# proper %Config::Config path (and thus gets caching, man -k, etc),
+# or else perldoc on obstreperous platforms.
+# + Added to and rearranged the help information.
+# + Detected apparent misuse of { ... } to declare a block; this used
+# to work but now is a command, and mysteriously gave no complaint.
####################################################################
$pre = [] unless defined $pre;
$post = [] unless defined $post;
$pretype = [] unless defined $pretype;
+
warnLevel($warnLevel);
dieLevel($dieLevel);
signalLevel($signalLevel);
-&pager((defined($ENV{PAGER})
+
+&pager(
+ (defined($ENV{PAGER})
? $ENV{PAGER}
: ($^O eq 'os2'
? 'cmd /c more'
: 'more'))) unless defined $pager;
+setman();
&recallCommand("!") unless defined $prc;
&shellBang("!") unless defined $psh;
$maxtrace = 400 unless defined $maxtrace;
-if (-e "/dev/tty") {
+if (-e "/dev/tty") { # this is the wrong metric!
$rcfile=".perldb";
} else {
$rcfile="perldb.ini";
}
+# This isn't really safe, because there's a race
+# between checking and opening. The solution is to
+# open and fstat the handle, but then you have to read and
+# eval the contents. But then the silly thing gets
+# your lexical scope, which is unfortunately at best.
+sub safe_do {
+ my $file = shift;
+
+ # Just exactly what part of the word "CORE::" don't you understand?
+ local $SIG{__WARN__};
+ local $SIG{__DIE__};
+
+ unless (is_safe_file($file)) {
+ CORE::warn <<EO_GRIPE;
+perldb: Must not source insecure rcfile $file.
+ You or the superuser must be the owner, and it must not
+ be writable by anyone but its owner.
+EO_GRIPE
+ return;
+ }
+
+ do $file;
+ CORE::warn("perldb: couldn't parse $file: $@") if $@;
+}
+
+
+# Verifies that owner is either real user or superuser and that no
+# one but owner may write to it. This function is of limited use
+# when called on a path instead of upon a handle, because there are
+# no guarantees that filename (by dirent) whose file (by ino) is
+# eventually accessed is the same as the one tested.
+# Assumes that the file's existence is not in doubt.
+sub is_safe_file {
+ my $path = shift;
+ stat($path) || return; # mysteriously vaporized
+ my($dev,$ino,$mode,$nlink,$uid,$gid) = stat(_);
+
+ return 0 if $uid != 0 && $uid != $<;
+ return 0 if $mode & 022;
+ return 1;
+}
+
if (-f $rcfile) {
- do "./$rcfile";
-} elsif (defined $ENV{LOGDIR} and -f "$ENV{LOGDIR}/$rcfile") {
- do "$ENV{LOGDIR}/$rcfile";
-} elsif (defined $ENV{HOME} and -f "$ENV{HOME}/$rcfile") {
- do "$ENV{HOME}/$rcfile";
+ safe_do("./$rcfile");
+}
+elsif (defined $ENV{HOME} && -f "$ENV{HOME}/$rcfile") {
+ safe_do("$ENV{HOME}/$rcfile");
+}
+elsif (defined $ENV{LOGDIR} && -f "$ENV{LOGDIR}/$rcfile") {
+ safe_do("$ENV{LOGDIR}/$rcfile");
}
if (defined $ENV{PERLDB_OPTS}) {
parse_options($ENV{PERLDB_OPTS});
}
+# Here begin the unreadable code. It needs fixing.
+
if (exists $ENV{PERLDB_RESTART}) {
delete $ENV{PERLDB_RESTART};
# $restart = 1;
if ($notty) {
$runnonstop = 1;
} else {
- # Is Perl being run from Emacs?
- $emacs = ((defined $main::ARGV[0]) and ($main::ARGV[0] eq '-emacs'));
- $rl = 0, shift(@main::ARGV) if $emacs;
+ # Is Perl being run from a slave editor or graphical debugger?
+ $slave_editor = ((defined $main::ARGV[0]) and ($main::ARGV[0] eq '-emacs'));
+ $rl = 0, shift(@main::ARGV) if $slave_editor;
#require Term::ReadLine;
$console = "sys\$command";
}
- if (($^O eq 'MSWin32') and ($emacs or defined $ENV{EMACS})) {
+ if (($^O eq 'MSWin32') and ($slave_editor or defined $ENV{EMACS})) {
$console = undef;
}
# Around a bug:
- if (defined $ENV{OS2_SHELL} and ($emacs or $ENV{WINDOWID})) { # In OS/2
+ if (defined $ENV{OS2_SHELL} and ($slave_editor or $ENV{WINDOWID})) { # In OS/2
$console = undef;
}
$header =~ s/.Header: ([^,]+),v(\s+\S+\s+\S+).*$/$1$2/;
unless ($runnonstop) {
print $OUT "\nLoading DB routines from $header\n";
- print $OUT ("Emacs support ",
- $emacs ? "enabled" : "available",
+ print $OUT ("Editor support ",
+ $slave_editor ? "enabled" : "available",
".\n");
- print $OUT "\nEnter h or `h h' for help, run `perldoc perldebug' for more help.\n\n";
+ print $OUT "\nEnter h or `h h' for help, or `$doccmd perldebug' for more help.\n\n";
}
}
$was_signal = $signal;
$signal = 0;
if ($single || ($trace & 1) || $was_signal) {
- if ($emacs) {
+ if ($slave_editor) {
$position = "\032\032$filename:$line:0\n";
print $LINEINFO $position;
} elsif ($package eq 'DB::fake') {
($term_pid == $$ or &resetterm),
defined ($cmd=&readline(" DB" . ('<' x $level) .
($#hist+1) . ('>' x $level) .
- " "))) {
+ " ")))
+ {
$single = 0;
$signal = 0;
$cmd =~ s/\\$/\n/ && do {
push(@hist,$cmd) if length($cmd) > 1;
PIPE: {
($i) = split(/\s+/,$cmd);
- eval "\$cmd =~ $alias{$i}", print $OUT $@ if $alias{$i};
+ #eval "\$cmd =~ $alias{$i}", print $OUT $@ if $alias{$i};
+ if ($alias{$i}) {
+ print STDERR "ALIAS $cmd INTO ";
+ eval "\$cmd =~ $alias{$i}";
+ print "$cmd\n";
+ print $OUT $@;
+ }
+ $cmd =~ s/^\s+//s; # trim annoying leading whitespace
+ $cmd =~ s/\s+$//s; # trim annoying trailing whitespace
$cmd =~ /^q$/ && ($exiting = 1) && exit 0;
$cmd =~ /^h$/ && do {
print_help($help);
$cmd =~ /^h\s+h$/ && do {
print_help($summary);
next CMD; };
- $cmd =~ /^h\s+(\S)$/ && do {
- my $asked = "\Q$1";
- if ($help =~ /^(?:[IB]<)$asked/m) {
- while ($help =~ /^((?:[IB]<)$asked([\s\S]*?)\n)(?!\s)/mg) {
+ # support long commands; otherwise bogus errors
+ # happen when you ask for h on <CR> for example
+ $cmd =~ /^h\s+(\S.*)$/ && do {
+ my $asked = $1; # for proper errmsg
+ my $qasked = quotemeta($asked); # for searching
+ # XXX: finds CR but not <CR>
+ if ($help =~ /^<?(?:[IB]<)$qasked/m) {
+ while ($help =~ /^(<?(?:[IB]<)$qasked([\s\S]*?)\n)(?!\s)/mg) {
print_help($1);
}
} else {
if (defined &main::dumpvar) {
local $frame = 0;
local $doret = -2;
- &main::dumpvar($packname,@vars);
+ # must detect sigpipe failures
+ eval { &main::dumpvar($packname,@vars) };
+ if ($@) {
+ die unless $@ =~ /dumpvar print failed/;
+ }
} else {
print $OUT "dumpvar.pl not available.\n";
}
$file = join(':', @pieces);
if ($file ne $filename) {
print $OUT "Switching to file '$file'.\n"
- unless $emacs;
+ unless $slave_editor;
*dbline = $main::{'_<' . $file};
$max = $#dbline;
$filename = $file;
$i = $line if $i eq '.';
$i = 1 if $i < 1;
$incr = $end - $i;
- if ($emacs) {
+ if ($slave_editor) {
print $OUT "\032\032$filename:$i:0\n";
$i = $end;
} else {
}
}
- if (not $had_breakpoints{$file} &= ~2) {
+ unless ($had_breakpoints{$file} &= ~2) {
delete $had_breakpoints{$file};
}
}
push @$post, action($1);
next CMD; };
$cmd =~ /^<\s*(.*)/ && do {
- $pre = [], next CMD unless $1;
+ unless ($1) {
+ print OUT "All < actions cleared.\n";
+ $pre = [];
+ next CMD;
+ }
+ if ($1 eq '?') {
+ unless (@$pre) {
+ print OUT "No pre-prompt Perl actions.\n";
+ next CMD;
+ }
+ print OUT "Perl commands run before each prompt:\n";
+ for my $action ( @$pre ) {
+ print "\t< -- $action\n";
+ }
+ next CMD;
+ }
$pre = [action($1)];
next CMD; };
$cmd =~ /^>\s*(.*)/ && do {
- $post = [], next CMD unless $1;
+ unless ($1) {
+ print OUT "All > actions cleared.\n";
+ $post = [];
+ next CMD;
+ }
+ if ($1 eq '?') {
+ unless (@$post) {
+ print OUT "No post-prompt Perl actions.\n";
+ next CMD;
+ }
+ print OUT "Perl commands run after each prompt:\n";
+ for my $action ( @$post ) {
+ print "\t> -- $action\n";
+ }
+ next CMD;
+ }
$post = [action($1)];
next CMD; };
$cmd =~ /^\{\{\s*(.*)/ && do {
+ if ($cmd =~ /^\{.*\}$/ && unbalanced(substr($cmd,2))) {
+ print OUT "{{ is now a debugger command\n",
+ "use `;{{' if you mean Perl code\n";
+ $cmd = "h {{";
+ redo CMD;
+ }
push @$pretype, $1;
next CMD; };
$cmd =~ /^\{\s*(.*)/ && do {
- $pretype = [], next CMD unless $1;
+ unless ($1) {
+ print OUT "All { actions cleared.\n";
+ $pretype = [];
+ next CMD;
+ }
+ if ($1 eq '?') {
+ unless (@$pretype) {
+ print OUT "No pre-prompt debugger actions.\n";
+ next CMD;
+ }
+ print OUT "Debugger commands run before each prompt:\n";
+ for my $action ( @$pretype ) {
+ print "\t{ -- $action\n";
+ }
+ next CMD;
+ }
+ if ($cmd =~ /^\{.*\}$/ && unbalanced(substr($cmd,1))) {
+ print OUT "{ is now a debugger command\n",
+ "use `;{' if you mean Perl code\n";
+ $cmd = "h {";
+ redo CMD;
+ }
$pretype = [$1];
next CMD; };
$cmd =~ /^a\b\s*(\d*)\s*(.*)/ && do {
set_list("PERLDB_INC", @ini_INC);
if ($0 eq '-e') {
for (1..$#{'::_<-e'}) { # The first line is PERL5DB
- chomp ($cl = $ {'::_<-e'}[$_]);
+ chomp ($cl = ${'::_<-e'}[$_]);
push @script, '-e', $cl;
}
} else {
set_list("PERLDB_POST", @$post);
set_list("PERLDB_TYPEAHEAD", @typeahead);
$ENV{PERLDB_RESTART} = 1;
- #print "$^X, '-d', @flags, @script, ($emacs ? '-emacs' : ()), @ARGS";
- exec $^X, '-d', @flags, @script, ($emacs ? '-emacs' : ()), @ARGS;
+ #print "$^X, '-d', @flags, @script, ($slave_editor ? '-emacs' : ()), @ARGS";
+ exec $^X, '-d', @flags, @script, ($slave_editor ? '-emacs' : ()), @ARGS;
print $OUT "exec failed: $!\n";
last CMD; };
$cmd =~ /^T$/ && do {
$start = 1 if ($start > $max);
last if ($start == $end);
if ($dbline[$start] =~ m' . "\a$pat\a" . 'i) {
- if ($emacs) {
+ if ($slave_editor) {
print $OUT "\032\032$filename:$start:0\n";
} else {
print $OUT "$start:\t", $dbline[$start], "\n";
$start = $max if ($start <= 0);
last if ($start == $end);
if ($dbline[$start] =~ m' . "\a$pat\a" . 'i) {
- if ($emacs) {
+ if ($slave_editor) {
print $OUT "\032\032$filename:$start:0\n";
} else {
print $OUT "$start:\t", $dbline[$start], "\n";
&system($ENV{SHELL}||"/bin/sh");
next CMD; };
$cmd =~ /^$sh\s*([\x00-\xff]*)/ && do {
+ # XXX: using csh or tcsh destroys sigint retvals!
+ #&system($1); # use this instead
&system($ENV{SHELL}||"/bin/sh","-c",$1);
next CMD; };
$cmd =~ /^H\b\s*(-(\d+))?/ && do {
- $end = $2?($#hist-$2):0;
+ $end = $2 ? ($#hist-$2) : 0;
$hist = 0 if $hist < 0;
for ($i=$#hist; $i>$end; $i--) {
print $OUT "$i: ",$hist[$i],"\n"
unless $hist[$i] =~ /^.?$/;
};
next CMD; };
+ $cmd =~ /^(?:man|(?:perl)?doc)\b(?:\s+([^(]*))?$/ && do {
+ runman($1);
+ next CMD; };
$cmd =~ s/^p$/print {\$DB::OUT} \$_/;
$cmd =~ s/^p\b/print {\$DB::OUT} /;
$cmd =~ /^=/ && do {
} else {
open(SAVEOUT,">&OUT") || &warn("Can't save DB::OUT");
}
+ fix_less();
unless ($piped=open(OUT,$pager)) {
&warn("Can't pipe output to `$pager'");
if ($pager =~ /^\|/) {
- open(OUT,">&STDOUT") || &warn("Can't restore DB::OUT");
+ open(OUT,">&STDOUT") # XXX: lost message
+ || &warn("Can't restore DB::OUT");
open(STDOUT,">&SAVEOUT")
|| &warn("Can't restore STDOUT");
close(SAVEOUT);
} else {
- open(OUT,">&STDOUT") || &warn("Can't restore DB::OUT");
+ open(OUT,">&STDOUT") # XXX: lost message
+ || &warn("Can't restore DB::OUT");
}
next CMD;
}
$SIG{PIPE}= \&DB::catch if $pager =~ /^\|/
- && "" eq $SIG{PIPE} || "DEFAULT" eq $SIG{PIPE};
+ && ("" eq $SIG{PIPE} || "DEFAULT" eq $SIG{PIPE});
$selected= select(OUT);
$|= 1;
select( $selected ), $selected= "" unless $cmd =~ /^\|\|/;
$cmd =~ s/^\|+\s*//;
- redo PIPE; };
+ redo PIPE;
+ };
# XXX Local variants do not work!
$cmd =~ s/^t\s/\$DB::trace |= 1;\n/;
$cmd =~ s/^s\s/\$DB::single = 1;\n/ && do {$laststep = 's'};
} continue { # CMD:
if ($piped) {
if ($pager =~ /^\|/) {
- $?= 0; close(OUT) || &warn("Can't close DB::OUT");
- &warn( "Pager `$pager' failed: ",
- ($?>>8) > 128 ? ($?>>8)-256 : ($?>>8),
- ( $? & 128 ) ? " (core dumped)" : "",
- ( $? & 127 ) ? " (SIG ".($?&127).")" : "", "\n" ) if $?;
+ $? = 0;
+ # we cannot warn here: the handle is missing --tchrist
+ close(OUT) || print SAVEOUT "\nCan't close DB::OUT\n";
+
+ # most of the $? crud was coping with broken cshisms
+ if ($?) {
+ print SAVEOUT "Pager `$pager' failed: ";
+ if ($? == -1) {
+ print SAVEOUT "shell returned -1\n";
+ } elsif ($? >> 8) {
+ print SAVEOUT
+ ( $? & 127 ) ? " (SIG#".($?&127).")" : "",
+ ( $? & 128 ) ? " -- core dumped" : "", "\n";
+ } else {
+ print SAVEOUT "status ", ($? >> 8), "\n";
+ }
+ }
+
open(OUT,">&STDOUT") || &warn("Can't restore DB::OUT");
open(STDOUT,">&SAVEOUT") || &warn("Can't restore STDOUT");
- $SIG{PIPE}= "DEFAULT" if $SIG{PIPE} eq \&DB::catch;
+ $SIG{PIPE} = "DEFAULT" if $SIG{PIPE} eq \&DB::catch;
# Will stop ignoring SIGPIPE if done like nohup(1)
# does SIGINT but Perl doesn't give us a choice.
} else {
# The following takes its argument via $evalarg to preserve current @_
sub eval {
- local @res; # 'my' would make it visible from user code
+ # 'my' would make it visible from user code
+ # but so does local! --tchrist
+ local @res;
{
local $otrace = $trace;
local $osingle = $single;
#%dbline = %{$postponed_file{$filename}}; # Cannot be done: unsufficient magic
my $key;
for $key (keys %{$postponed_file{$filename}}) {
- $dbline{$key} = $ {$postponed_file{$filename}}{$key};
+ $dbline{$key} = ${$postponed_file{$filename}}{$key};
}
delete $postponed_file{$filename};
}
$action;
}
+sub unbalanced {
+ # i hate using globals!
+ $balanced_brace_re ||= qr{
+ ^ \{
+ (?:
+ (?> [^{}] + ) # Non-parens without backtracking
+ |
+ (??{ $balanced_brace_re }) # Group with matching parens
+ ) *
+ \} $
+ }x;
+ return $_[0] !~ m/$balanced_brace_re/;
+}
+
sub gets {
local($.);
#<IN>;
sub system {
# We save, change, then restore STDIN and STDOUT to avoid fork() since
- # many non-Unix systems can do system() but have problems with fork().
+ # some non-Unix systems can do system() but have problems with fork().
open(SAVEIN,"<&STDIN") || &warn("Can't save STDIN");
open(SAVEOUT,">&STDOUT") || &warn("Can't save STDOUT");
open(STDIN,"<&IN") || &warn("Can't redirect STDIN");
open(STDOUT,">&OUT") || &warn("Can't redirect STDOUT");
+
+ # XXX: using csh or tcsh destroys sigint retvals!
system(@_);
open(STDIN,"<&SAVEIN") || &warn("Can't restore STDIN");
open(STDOUT,">&SAVEOUT") || &warn("Can't restore STDOUT");
- close(SAVEIN); close(SAVEOUT);
- &warn( "(Command returned ", ($?>>8) > 128 ? ($?>>8)-256 : ($?>>8), ")",
- ( $? & 128 ) ? " (core dumped)" : "",
- ( $? & 127 ) ? " (SIG ".($?&127).")" : "", "\n" ) if $?;
- $?;
+ close(SAVEIN);
+ close(SAVEOUT);
+
+
+ # most of the $? crud was coping with broken cshisms
+ if ($? >> 8) {
+ &warn("(Command exited ", ($? >> 8), ")\n");
+ } elsif ($?) {
+ &warn( "(Command died of SIG#", ($? & 127),
+ (($? & 128) ? " -- core dumped" : "") , ")", "\n");
+ }
+
+ return $?;
+
}
sub setterm {
if (ref $OUT and UNIVERSAL::isa($OUT, 'IO::Socket::INET')) {
print $OUT @_;
my $stuff;
- $IN->recv( $stuff, 2048 );
+ $IN->recv( $stuff, 2048 ); # XXX: what's wrong with sysread?
$stuff;
}
else {
my ($opt, $default)= @_;
my $val;
if (defined $optionVars{$opt}
- and defined $ {$optionVars{$opt}}) {
- $val = $ {$optionVars{$opt}};
+ and defined ${$optionVars{$opt}}) {
+ $val = ${$optionVars{$opt}};
} elsif (defined $optionAction{$opt}
and defined &{$optionAction{$opt}}) {
$val = &{$optionAction{$opt}}();
} elsif (defined $optionAction{$opt}
and not defined $option{$opt}
or defined $optionVars{$opt}
- and not defined $ {$optionVars{$opt}}) {
+ and not defined ${$optionVars{$opt}}) {
$val = $default;
} else {
$val = $option{$opt};
sub parse_options {
local($_)= @_;
- while ($_ ne "") {
- s/^(\w+)(\s*$|\W)// or print($OUT "Invalid option `$_'\n"), last;
+ # too dangerous to let intuitive usage overwrite important things
+ # defaultion should never be the default
+ my %opt_needs_val = map { ( $_ => 1 ) } qw{
+ arrayDepth hashDepth LineInfo maxTraceLen noTTY ornaments
+ pager quote ReadLine recallCommand RemotePort ShellBang TTY
+ };
+ while (length) {
+ my $val_defaulted;
+ s/^\s+// && next;
+ s/^(\w+)(\W?)// or print($OUT "Invalid option `$_'\n"), last;
my ($opt,$sep) = ($1,$2);
my $val;
if ("?" eq $sep) {
if /^\S/;
#&dump_option($opt);
} elsif ($sep !~ /\S/) {
- $val = "1";
+ $val_defaulted = 1;
+ $val = "1"; # this is an evil default; make 'em set it!
} elsif ($sep eq "=") {
- s/^(\S*)($|\s+)//;
+
+ if (s/ (["']) ( (?: \\. | (?! \1 ) [^\\] )* ) \1 //x) {
+ my $quote = $1;
+ ($val = $2) =~ s/\\([$quote\\])/$1/g;
+ } else {
+ s/^(\S*)//;
$val = $1;
+ print OUT qq(Option better cleared using $opt=""\n)
+ unless length $val;
+ }
+
} else { #{ to "let some poor schmuck bounce on the % key in B<vi>."
my ($end) = "\\" . substr( ")]>}$sep", index("([<{",$sep), 1 ); #}
s/^(([^\\$end]|\\[\\$end])*)$end($|\s+)// or
print($OUT "Unclosed option value `$opt$sep$_'\n"), last;
- $val = $1;
- $val =~ s/\\([\\$end])/$1/g;
+ ($val = $1) =~ s/\\([\\$end])/$1/g;
}
- my ($option);
- my $matches =
- grep( /^\Q$opt/ && ($option = $_), @options );
- $matches = grep( /^\Q$opt/i && ($option = $_), @options )
- unless $matches;
- print $OUT "Unknown option `$opt'\n" unless $matches;
- print $OUT "Ambiguous option `$opt'\n" if $matches > 1;
- $option{$option} = $val if $matches == 1 and defined $val;
- eval "local \$frame = 0; local \$doret = -2;
- require '$optionRequire{$option}'"
- if $matches == 1 and defined $optionRequire{$option} and defined $val;
- $ {$optionVars{$option}} = $val
- if $matches == 1
- and defined $optionVars{$option} and defined $val;
- & {$optionAction{$option}} ($val)
- if $matches == 1
- and defined $optionAction{$option}
- and defined &{$optionAction{$option}} and defined $val;
- &dump_option($option) if $matches == 1 && $OUT ne \*STDERR; # Not $rcfile
- s/^\s+//;
+
+ my $option;
+ my $matches = grep( /^\Q$opt/ && ($option = $_), @options )
+ || grep( /^\Q$opt/i && ($option = $_), @options );
+
+ print($OUT "Unknown option `$opt'\n"), next unless $matches;
+ print($OUT "Ambiguous option `$opt'\n"), next if $matches > 1;
+
+ if ($opt_needs_val{$option} && $val_defaulted) {
+ print $OUT "Option `$opt' is non-boolean. Use `O $option=VAL' to set, `O $option?' to query\n";
+ next;
+ }
+
+ $option{$option} = $val if defined $val;
+
+ eval qq{
+ local \$frame = 0;
+ local \$doret = -2;
+ require '$optionRequire{$option}';
+ 1;
+ } || die # XXX: shouldn't happen
+ if defined $optionRequire{$option} &&
+ defined $val;
+
+ ${$optionVars{$option}} = $val
+ if defined $optionVars{$option} &&
+ defined $val;
+
+ &{$optionAction{$option}} ($val)
+ if defined $optionAction{$option} &&
+ defined &{$optionAction{$option}} &&
+ defined $val;
+
+ # Not $rcfile
+ dump_option($option) unless $OUT eq \*STDERR;
}
}
sub set_list {
my ($stem,@list) = @_;
my $val;
- $ENV{"$ {stem}_n"} = @list;
+ $ENV{"${stem}_n"} = @list;
for $i (0 .. $#list) {
$val = $list[$i];
$val =~ s/\\/\\\\/g;
$val =~ s/([\0-\37\177\200-\377])/"\\0x" . unpack('H2',$1)/eg;
- $ENV{"$ {stem}_$i"} = $val;
+ $ENV{"${stem}_$i"} = $val;
}
}
sub get_list {
my $stem = shift;
my @list;
- my $n = delete $ENV{"$ {stem}_n"};
+ my $n = delete $ENV{"${stem}_n"};
my $val;
for $i (0 .. $n - 1) {
- $val = delete $ENV{"$ {stem}_$i"};
+ $val = delete $ENV{"${stem}_$i"};
$val =~ s/\\((\\)|0x(..))/ $2 ? $2 : pack('H2', $3) /ge;
push @list, $val;
}
}
sub tkRunning {
- if ($ {$term->Features}{tkRunning}) {
+ if (${$term->Features}{tkRunning}) {
return $term->tkRunning(@_);
} else {
print $OUT "tkRunning not supported by current ReadLine package.\n";
return $lineinfo unless @_;
$lineinfo = shift;
my $stream = ($lineinfo =~ /^(\+?\>|\|)/) ? $lineinfo : ">$lineinfo";
- $emacs = ($stream =~ /^\|/);
+ $slave_editor = ($stream =~ /^\|/);
open(LINEINFO, "$stream") || &warn("Cannot open `$stream' for write");
$LINEINFO = \*LINEINFO;
my $save = select($LINEINFO);
s,/,::,g ;
s/^perl5db$/DB/;
s/^Term::ReadLine::readline$/readline/;
- if (defined $ { $_ . '::VERSION' }) {
- $version{$file} = "$ { $_ . '::VERSION' } from ";
+ if (defined ${ $_ . '::VERSION' }) {
+ $version{$file} = "${ $_ . '::VERSION' } from ";
}
$version{$file} .= $INC{$file};
}
}
sub sethelp {
+ # XXX: make sure these are tabs between the command and explantion,
+ # or print_help will screw up your formatting if you have
+ # eeevil ornaments enabled. This is an insane mess.
+
$help = "
B<T> Stack trace.
B<s> [I<expr>] Single step [in I<expr>].
B<m> I<expr> Evals expression in array context, prints methods callable
on the first element of the result.
B<m> I<class> Prints methods callable via the given class.
-B<O> [I<opt>[B<=>I<val>]] [I<opt>B<\">I<val>B<\">] [I<opt>B<?>]...
- Set or query values of options. I<val> defaults to 1. I<opt> can
- be abbreviated. Several options can be listed.
- I<recallCommand>, I<ShellBang>: chars used to recall command or spawn shell;
- I<pager>: program for output of \"|cmd\";
- I<tkRunning>: run Tk while prompting (with ReadLine);
- I<signalLevel> I<warnLevel> I<dieLevel>: level of verbosity;
- I<inhibit_exit> Allows stepping off the end of the script.
- I<ImmediateStop> Debugger should stop as early as possible.
- I<RemotePort>: Remote hostname:port for remote debugging
- The following options affect what happens with B<V>, B<X>, and B<x> commands:
- I<arrayDepth>, I<hashDepth>: print only first N elements ('' for all);
- I<compactDump>, I<veryCompact>: change style of array and hash dump;
- I<globPrint>: whether to print contents of globs;
- I<DumpDBFiles>: dump arrays holding debugged files;
- I<DumpPackages>: dump symbol tables of packages;
- I<DumpReused>: dump contents of \"reused\" addresses;
- I<quote>, I<HighBit>, I<undefPrint>: change style of string dump;
- I<bareStringify>: Do not print the overload-stringified value;
- Option I<PrintRet> affects printing of return value after B<r> command,
- I<frame> affects printing messages on entry and exit from subroutines.
- I<AutoTrace> affects printing messages on every possible breaking point.
- I<maxTraceLen> gives maximal length of evals/args listed in stack trace.
- I<ornaments> affects screen appearance of the command line.
- During startup options are initialized from \$ENV{PERLDB_OPTS}.
- You can put additional initialization options I<TTY>, I<noTTY>,
- I<ReadLine>, I<NonStop>, and I<RemotePort> there (or use
- `B<R>' after you set them).
+
+B<<> ? List Perl commands to run before each prompt.
B<<> I<expr> Define Perl command to run before each prompt.
B<<<> I<expr> Add to the list of Perl commands to run before each prompt.
+B<>> ? List Perl commands to run after each prompt.
B<>> I<expr> Define Perl command to run after each prompt.
B<>>B<>> I<expr> Add to the list of Perl commands to run after each prompt.
B<{> I<db_command> Define debugger command to run before each prompt.
+B<{> ? List debugger commands to run before each prompt.
+B<<> I<expr> Define Perl command to run before each prompt.
B<{{> I<db_command> Add to the list of debugger commands to run before each prompt.
B<$prc> I<number> Redo a previous command (default previous command).
B<$prc> I<-number> Redo number'th-to-last command.
Currently the following setting are preserved:
history, breakpoints and actions, debugger B<O>ptions
and the following command-line options: I<-w>, I<-I>, I<-e>.
+
+B<O> [I<opt>] ... Set boolean option to true
+B<O> [I<opt>B<?>] Query options
+B<O> [I<opt>B<=>I<val>] [I<opt>=B<\">I<val>B<\">] ...
+ Set options. Use quotes in spaces in value.
+ I<recallCommand>, I<ShellBang> chars used to recall command or spawn shell;
+ I<pager> program for output of \"|cmd\";
+ I<tkRunning> run Tk while prompting (with ReadLine);
+ I<signalLevel> I<warnLevel> I<dieLevel> level of verbosity;
+ I<inhibit_exit> Allows stepping off the end of the script.
+ I<ImmediateStop> Debugger should stop as early as possible.
+ I<RemotePort> Remote hostname:port for remote debugging
+ The following options affect what happens with B<V>, B<X>, and B<x> commands:
+ I<arrayDepth>, I<hashDepth> print only first N elements ('' for all);
+ I<compactDump>, I<veryCompact> change style of array and hash dump;
+ I<globPrint> whether to print contents of globs;
+ I<DumpDBFiles> dump arrays holding debugged files;
+ I<DumpPackages> dump symbol tables of packages;
+ I<DumpReused> dump contents of \"reused\" addresses;
+ I<quote>, I<HighBit>, I<undefPrint> change style of string dump;
+ I<bareStringify> Do not print the overload-stringified value;
+ Other options include:
+ I<PrintRet> affects printing of return value after B<r> command,
+ I<frame> affects printing messages on entry and exit from subroutines.
+ I<AutoTrace> affects printing messages on every possible breaking point.
+ I<maxTraceLen> gives maximal length of evals/args listed in stack trace.
+ I<ornaments> affects screen appearance of the command line.
+ During startup options are initialized from \$ENV{PERLDB_OPTS}.
+ You can put additional initialization options I<TTY>, I<noTTY>,
+ I<ReadLine>, I<NonStop>, and I<RemotePort> there (or use
+ `B<R>' after you set them).
+
+B<q> or B<^D> Quit. Set B<\$DB::finished = 0> to debug global destruction.
B<h> [I<db_command>] Get help [on a specific debugger command], enter B<|h> to page.
- Complete description of debugger is available in B<perldebug>
- section of Perl documention
B<h h> Summary of debugger commands.
-B<q> or B<^D> Quit. Set B<\$DB::finished = 0> to debug global destruction.
+B<$doccmd> I<manpage> Runs the external doc viewer B<$doccmd> command on the
+ named Perl I<manpage>, or on B<$doccmd> itself if omitted.
+ Set B<\$DB::doccmd> to change viewer.
+
+Type `|h' for a paged display if this was too hard to read.
+
+"; # Fix balance of vi % matching: } }}
-";
$summary = <<"END_SUM";
I<List/search source lines:> I<Control script execution:>
B<l> [I<ln>|I<sub>] List source code B<T> Stack trace
B<S> [[B<!>]I<pat>] List subroutine names [not] matching pattern
B<V> [I<Pk> [I<Vars>]] List Variables in Package. Vars can be ~pattern or !pattern.
B<X> [I<Vars>] Same as \"B<V> I<current_package> [I<Vars>]\".
-I<More help for> B<db_cmd>I<:> Type B<h> I<cmd_letter> Run B<perldoc perldebug> for more help.
+For more help, type B<h> I<cmd_letter>, or run B<$doccmd perldebug> for all docs.
END_SUM
- # ')}}; # Fix balance of Emacs parsing
+ # ')}}; # Fix balance of vi % matching
}
sub print_help {
- my $message = shift;
- if (@Term::ReadLine::TermCap::rl_term_set) {
- $message =~ s/B<([^>]+|>)>/$Term::ReadLine::TermCap::rl_term_set[2]$1$Term::ReadLine::TermCap::rl_term_set[3]/g;
- $message =~ s/I<([^>]+|>)>/$Term::ReadLine::TermCap::rl_term_set[0]$1$Term::ReadLine::TermCap::rl_term_set[1]/g;
- }
- print $OUT $message;
+ local $_ = shift;
+
+ # Restore proper alignment destroyed by eeevil I<> and B<>
+ # ornaments: A pox on both their houses!
+ #
+ # A help command will have everything up to and including
+ # the first tab sequence paddeed into a field 16 (or if indented 20)
+ # wide. If it's wide than that, an extra space will be added.
+ s{
+ ^ # only matters at start of line
+ ( \040{4} | \t )* # some subcommands are indented
+ ( < ? # so <CR> works
+ [BI] < [^\t\n] + ) # find an eeevil ornament
+ ( \t+ ) # original separation, discarded
+ ( .* ) # this will now start (no earlier) than
+ # column 16
+ } {
+ my($leadwhite, $command, $midwhite, $text) = ($1, $2, $3, $4);
+ my $clean = $command;
+ $clean =~ s/[BI]<([^>]*)>/$1/g;
+ # replace with this whole string:
+ (length($leadwhite) ? " " x 4 : "")
+ . $command
+ . ((" " x (16 + (length($leadwhite) ? 4 : 0) - length($clean))) || " ")
+ . $text;
+
+ }mgex;
+
+ s{ # handle bold ornaments
+ B < ( [^>] + | > ) >
+ } {
+ $Term::ReadLine::TermCap::rl_term_set[2]
+ . $1
+ . $Term::ReadLine::TermCap::rl_term_set[3]
+ }gex;
+
+ s{ # handle italic ornaments
+ I < ( [^>] + | > ) >
+ } {
+ $Term::ReadLine::TermCap::rl_term_set[0]
+ . $1
+ . $Term::ReadLine::TermCap::rl_term_set[1]
+ }gex;
+
+ print $OUT $_;
+}
+
+sub fix_less {
+ return if defined $ENV{LESS} && $ENV{LESS} =~ /r/;
+ my $is_less = $pager =~ /\bless\b/;
+ if ($pager =~ /\bmore\b/) {
+ my @st_more = stat('/usr/bin/more');
+ my @st_less = stat('/usr/bin/less');
+ $is_less = @st_more && @st_less
+ && $st_more[0] == $st_less[0]
+ && $st_more[1] == $st_less[1];
+ }
+ # changes environment!
+ $ENV{LESS} .= 'r' if $is_less;
}
sub diesignal {
}
eval { require Carp } if defined $^S; # If error/warning during compilation,
# require may be broken.
+
die(@_, "\nCannot print stack trace, load with -MCarp option to see stack")
unless defined &Carp::longmess;
+
# We do not want to debug this chunk (automatic disabling works
# inside DB::DB, but not in Carp).
my ($mysingle,$mytrace) = ($single,$trace);
my $prefix = shift;
my $prepend = $prefix ? "via $prefix: " : '';
my $name;
- for $name (grep {defined &{$ {"$ {class}::"}{$_}}}
- sort keys %{"$ {class}::"}) {
+ for $name (grep {defined &{${"${class}::"}{$_}}}
+ sort keys %{"${class}::"}) {
next if $seen{ $name }++;
print $DB::OUT "$prepend$name\n";
}
return unless shift; # Recurse?
- for $name (@{"$ {class}::ISA"}) {
+ for $name (@{"${class}::ISA"}) {
$prepend = $prefix ? $prefix . " -> $name" : $name;
methods_via($name, $prepend, 1);
}
}
+sub setman {
+ $doccmd = $^O !~ /^(?:MSWin32|VMS|os2|dos|amigaos|riscos|MacOS)\z/s
+ ? "man" # O Happy Day!
+ : "perldoc"; # Alas, poor unfortunates
+}
+
+sub runman {
+ my $page = shift;
+ unless ($page) {
+ &system("$doccmd $doccmd");
+ return;
+ }
+ # this way user can override, like with $doccmd="man -Mwhatever"
+ # or even just "man " to disable the path check.
+ unless ($doccmd eq 'man') {
+ &system("$doccmd $page");
+ return;
+ }
+
+ $page = 'perl' if lc($page) eq 'help';
+
+ require Config;
+ my $man1dir = $Config::Config{'man1dir'};
+ my $man3dir = $Config::Config{'man3dir'};
+ for ($man1dir, $man3dir) { s#/[^/]*\z## if /\S/ }
+ my $manpath = '';
+ $manpath .= "$man1dir:" if $man1dir =~ /\S/;
+ $manpath .= "$man3dir:" if $man3dir =~ /\S/ && $man1dir ne $man3dir;
+ chop $manpath if $manpath;
+ # harmless if missing, I figure
+ my $oldpath = $ENV{MANPATH};
+ $ENV{MANPATH} = $manpath if $manpath;
+ my $nopathopt = $^O =~ /dunno what goes here/;
+ if (system($doccmd,
+ # I just *know* there are men without -M
+ (($manpath && !$nopathopt) ? ("-M", $manpath) : ()),
+ split ' ', $page) )
+ {
+ unless ($page =~ /^perl\w/) {
+ if (grep { $page eq $_ } qw{
+ 5004delta 5005delta amiga api apio book boot bot call compile
+ cygwin data dbmfilter debug debguts delta diag doc dos dsc embed
+ faq faq1 faq2 faq3 faq4 faq5 faq6 faq7 faq8 faq9 filter fork
+ form func guts hack hist hpux intern ipc lexwarn locale lol mod
+ modinstall modlib number obj op opentut os2 os390 pod port
+ ref reftut run sec style sub syn thrtut tie toc todo toot tootc
+ trap unicode var vms win32 xs xstut
+ })
+ {
+ $page =~ s/^/perl/;
+ system($doccmd,
+ (($manpath && !$nopathopt) ? ("-M", $manpath) : ()),
+ $page);
+ }
+ }
+ }
+ if (defined $oldpath) {
+ $ENV{MANPATH} = $manpath;
+ } else {
+ delete $ENV{MANPATH};
+ }
+}
+
# The following BEGIN is very handy if debugger goes havoc, debugging debugger?
BEGIN { # This does not compile, alas.
# Specific code for b c l V m f O, &blah, $blah, @blah, %blah
my($text, $line, $start) = @_;
my ($itext, $search, $prefix, $pack) =
- ($text, "^\Q$ {'package'}::\E([^:]+)\$");
+ ($text, "^\Q${'package'}::\E([^:]+)\$");
return sort grep /^\Q$text/, (keys %sub), qw(postpone load compile), # subroutines
(map { /$search/ ? ($1) : () } keys %sub)
perlembed Perl ways to embed perl in your C or C++ application
perlapio Perl internal IO abstraction interface
+ perldebguts Perl debugging guts and tips
perlxs Perl XS application programming interface
perlxstut Perl XS tutorial
perlguts Perl internal functions for those doing extensions
=head1 AVAILABILITY
Perl is available for most operating systems, including virtually
-all Unix-like platforms.
-
-As of early March 2000 (the Perl release 5.6.0), the following
-platforms are able to build Perl from the standard source code
-distribution available at http://www.perl.com/CPAN/src/index.html
-
- AIX
- DOS DJGPP 1)
- FreeBSD
- HP-UX
- IRIX
- Linux
- LynxOS
- MachTen
- MPE/iX
- NetBSD
- OpenBSD
- OS/2
- Rhapsody/Darwin 2)
- Solaris
- Tru64 UNIX 3)
- UNICOS
- UNICOS/mk
- VMS
- VOS
- Windows 3.1 1)
- Windows 95 1) 4)
- Windows 98 1) 4)
- Windows NT 1) 4)
-
- 1) in DOS mode either the DOS or OS/2 ports can be used
- 2) new in 5.6.0: the BSD/NeXT-based UNIX of Mac OS X
- 3) formerly known as Digital UNIX and before that DEC OSF/1
- 4) compilers: Borland, Cygwin, Mingw32 EGCS/GCC, VC++
-
-The following platforms worked for the previous major release
-(5.005_03 being the latest maintenance release of that, as of early
-March 2000), but be did not manage to test these in time for the 5.6.0
-release of Perl. There is a very good chance that these will work
-just fine with 5.6.0.
-
- A/UX
- BeOS
- BSD/OS
- DG/UX
- DYNIX/ptx
- DomainOS
- Hurd
- NextSTEP
- OpenSTEP
- PowerMAX
- QNX
- SCO ODT/OSR
- SunOS
- SVR4
- Ultrix
-
-The following platform worked for the previous major release (5.005_03
-being the latest maintenance release of that, as of early March 2000).
-However, standardization on UTF-8 as the internal string representation
-in 5.6.0 has introduced incompatibilities in this EBCDIC platform.
-Support for this platform may be enabled in a future release:
-
- OS390 1)
-
- 1) Previously known as MVS, or OpenEdition MVS.
-
-Strongly related to the OS390 platform by also being EBCDIC-based
-mainframe platforms are the following platforms:
-
- BS2000
- VM/ESA
-
-These are also not expected to work under 5.6.0 for the same reasons
-as OS390. Contact the mailing list perl-mvs@perl.org for more details.
-
-MacOS (Classic, pre-X) is almost 5.6.0-ready; building from the source
-does work with 5.6.0, but additional MacOS specific source code is needed
-for a complete port. Contact the mailing list macperl-porters@macperl.org
-for more more information.
-
-The following platforms have been known to build Perl from source in
-the past, but we haven't been able to verify their status for the
-current release, either because the hardware/software platforms are
-rare or because we don't have an active champion on these
-platforms--or both:
-
- 3b1
- AmigaOS
- ConvexOS
- CX/UX
- DC/OSx
- DDE SMES
- DOS EMX
- Dynix
- EP/IX
- ESIX
- FPS
- GENIX
- Greenhills
- ISC
- MachTen 68k
- MiNT
- MPC
- NEWS-OS
- Opus
- Plan 9
- PowerUX
- RISC/os
- Stellar
- SVR2
- TI1500
- TitanOS
- Unisys Dynix
- Unixware
-
-Support for the following platform is planned for a future Perl release:
-
- Netware
-
-The following platforms have their own source code distributions and
-binaries available via http://www.perl.com/CPAN/ports/index.html:
-
- Perl release
-
- AS/400 5.003
- Netware 5.003_07
- Tandem Guardian 5.004
-
-The following platforms have only binaries available via
-http://www.perl.com/CPAN/ports/index.html:
-
- Perl release
-
- Acorn RISCOS 5.005_02
- AOS 5.002
- LynxOS 5.004_02
-
-Although we do suggest that you always build your own Perl from
-the source code, both for maximal configurability and for security,
-in case you are in a hurry you can check
-http://www.perl.com/CPAN/ports/index.html for binary distributions.
+all Unix-like platforms. See L<perlport/"Supported Platforms">
+for a listing.
=head1 ENVIRONMENT
You may mail your bug reports (be sure to include full configuration
information as output by the myconfig program in the perl source
tree, or by C<perl -V>) to perlbug@perl.com . If you've succeeded
-in compiling perl, the perlbug script in the utils/ subdirectory
+in compiling perl, the B<perlbug> script in the F<utils/> subdirectory
can be used to help mail in a bug report.
Perl actually stands for Pathologically Eclectic Rubbish Lister, but
--- /dev/null
+=head1 NAME
+
+perldebguts - Guts of Perl debugging
+
+=head1 DESCRIPTION
+
+This is not the perldebug(1) manpage, which tells you how to use
+the debugger. This manpage describes low-level details ranging
+between difficult and impossible for anyone who isn't incredibly
+intimate with Perl's guts to understand. Caveat lector.
+
+=head1 Debugger Internals
+
+Perl has special debugging hooks at compile-time and run-time used
+to create debugging environments. These hooks are not to be confused
+with the I<perl -Dxxx> command described in L<perlrun>, which are
+usable only if a special Perl built per the instructions the
+F<INSTALL> podpage in the Perl source tree.
+
+For example, whenever you call Perl's built-in C<caller> function
+from the package DB, the arguments that the corresponding stack
+frame was called with are copied to the the @DB::args array. The
+general mechanisms is enabled by calling Perl with the B<-d> switch, the
+following additional features are enabled (cf. L<perlvar/$^P>):
+
+=over
+
+=item *
+
+Perl inserts the contents of C<$ENV{PERL5DB}> (or C<BEGIN {require
+'perl5db.pl'}> if not present) before the first line of your program.
+
+=item *
+
+The array C<@{"_<$filename"}> holds the lines of $filename for all
+files compiled by Perl. The same for C<eval>ed strings that contain
+subroutines, or which are currently being executed. The $filename
+for C<eval>ed strings looks like C<(eval 34)>. Code assertions
+in regexes look like C<(re_eval 19)>.
+
+=item *
+
+The hash C<%{"_<$filename"}> contains breakpoints and actions keyed
+by line number. Individual entries (as opposed to the whole hash)
+are settable. Perl only cares about Boolean true here, although
+the values used by F<perl5db.pl> have the form
+C<"$break_condition\0$action">. Values in this hash are magical
+in numeric context: they are zeros if the line is not breakable.
+
+The same holds for evaluated strings that contain subroutines, or
+which are currently being executed. The $filename for C<eval>ed strings
+looks like C<(eval 34)> or C<(re_eval 19)>.
+
+=item *
+
+The scalar C<${"_<$filename"}> contains C<"_<$filename">. This is
+also the case for evaluated strings that contain subroutines, or
+which are currently being executed. The $filename for C<eval>ed
+strings looks like C<(eval 34)> or C<(re_eval 19)>.
+
+=item *
+
+After each C<require>d file is compiled, but before it is executed,
+C<DB::postponed(*{"_<$filename"})> is called if the subroutine
+C<DB::postponed> exists. Here, the $filename is the expanded name of
+the C<require>d file, as found in the values of %INC.
+
+=item *
+
+After each subroutine C<subname> is compiled, the existence of
+C<$DB::postponed{subname}> is checked. If this key exists,
+C<DB::postponed(subname)> is called if the C<DB::postponed> subroutine
+also exists.
+
+=item *
+
+A hash C<%DB::sub> is maintained, whose keys are subroutine names
+and whose values have the form C<filename:startline-endline>.
+C<filename> has the form C<(eval 34)> for subroutines defined inside
+C<eval>s, or C<(re_eval 19)> for those within regex code assertions.
+
+=item *
+
+When the execution of your program reaches a point that can hold a
+breakpoint, the C<DB::DB()> subroutine is called any of the variables
+$DB::trace, $DB::single, or $DB::signal is true. These variables
+are not C<local>izable. This feature is disabled when executing
+inside C<DB::DB()>, including functions called from it
+unless C<< $^D & (1<<30) >> is true.
+
+=item *
+
+When execution of the program reaches a subroutine call, a call to
+C<&DB::sub>(I<args>) is made instead, with C<$DB::sub> holding the
+name of the called subroutine. This doesn't happen if the subroutine
+was compiled in the C<DB> package.)
+
+=back
+
+Note that if C<&DB::sub> needs external data for it to work, no
+subroutine call is possible until this is done. For the standard
+debugger, the C<$DB::deep> variable (how many levels of recursion
+deep into the debugger you can go before a mandatory break) gives
+an example of such a dependency.
+
+=head2 Writing Your Own Debugger
+
+The minimal working debugger consists of one line
+
+ sub DB::DB {}
+
+which is quite handy as contents of C<PERL5DB> environment
+variable:
+
+ $ PERL5DB="sub DB::DB {}" perl -d your-script
+
+Another brief debugger, slightly more useful, could be created
+with only the line:
+
+ sub DB::DB {print ++$i; scalar <STDIN>}
+
+This debugger would print the sequential number of encountered
+statement, and would wait for you to hit a newline before continuing.
+
+The following debugger is quite functional:
+
+ {
+ package DB;
+ sub DB {}
+ sub sub {print ++$i, " $sub\n"; &$sub}
+ }
+
+It prints the sequential number of subroutine call and the name of the
+called subroutine. Note that C<&DB::sub> should be compiled into the
+package C<DB>.
+
+At the start, the debugger reads your rc file (F<./.perldb> or
+F<~/.perldb> under Unix), which can set important options. This file may
+define a subroutine C<&afterinit> to be executed after the debugger is
+initialized.
+
+After the rc file is read, the debugger reads the PERLDB_OPTS
+environment variable and parses this as the remainder of a C<O ...>
+line as one might enter at the debugger prompt.
+
+The debugger also maintains magical internal variables, such as
+C<@DB::dbline>, C<%DB::dbline>, which are aliases for
+C<@{"::_<current_file"}> C<%{"::_<current_file"}>. Here C<current_file>
+is the currently selected file, either explicitly chosen with the
+debugger's C<f> command, or implicitly by flow of execution.
+
+Some functions are provided to simplify customization. See
+L<perldebug/"Options"> for description of options parsed by
+C<DB::parse_options(string)>. The function C<DB::dump_trace(skip[,
+count])> skips the specified number of frames and returns a list
+containing information about the calling frames (all of them, if
+C<count> is missing). Each entry is reference to a a hash with
+keys C<context> (either C<.>, C<$>, or C<@>), C<sub> (subroutine
+name, or info about C<eval>), C<args> (C<undef> or a reference to
+an array), C<file>, and C<line>.
+
+The function C<DB::print_trace(FH, skip[, count[, short]])> prints
+formatted info about caller frames. The last two functions may be
+convenient as arguments to C<< < >>, C<< << >> commands.
+
+Note that any variables and functions that are not documented in
+this manpages (or in L<perldebug>) are considered for internal
+use only, and as such are subject to change without notice.
+
+=head1 Frame Listing Output Examples
+
+The C<frame> option can be used to control the output of frame
+information. For example, contrast this expression trace:
+
+ $ perl -de 42
+ Stack dump during die enabled outside of evals.
+
+ Loading DB routines from perl5db.pl patch level 0.94
+ Emacs support available.
+
+ Enter h or `h h' for help.
+
+ main::(-e:1): 0
+ DB<1> sub foo { 14 }
+
+ DB<2> sub bar { 3 }
+
+ DB<3> t print foo() * bar()
+ main::((eval 172):3): print foo() + bar();
+ main::foo((eval 168):2):
+ main::bar((eval 170):2):
+ 42
+
+with this one, once the C<O>ption C<frame=2> has been set:
+
+ DB<4> O f=2
+ frame = '2'
+ DB<5> t print foo() * bar()
+ 3: foo() * bar()
+ entering main::foo
+ 2: sub foo { 14 };
+ exited main::foo
+ entering main::bar
+ 2: sub bar { 3 };
+ exited main::bar
+ 42
+
+By way of demonstration, we present below a laborious listing
+resulting from setting your C<PERLDB_OPTS> environment variable to
+the value C<f=n N>, and running I<perl -d -V> from the command line.
+Examples use various values of C<n> are shown to give you a feel
+for the difference between settings. Long those it may be, this
+is not a complete listing, but only excerpts.
+
+=over 4
+
+=item 1
+
+ entering main::BEGIN
+ entering Config::BEGIN
+ Package lib/Exporter.pm.
+ Package lib/Carp.pm.
+ Package lib/Config.pm.
+ entering Config::TIEHASH
+ entering Exporter::import
+ entering Exporter::export
+ entering Config::myconfig
+ entering Config::FETCH
+ entering Config::FETCH
+ entering Config::FETCH
+ entering Config::FETCH
+
+=item 2
+
+ entering main::BEGIN
+ entering Config::BEGIN
+ Package lib/Exporter.pm.
+ Package lib/Carp.pm.
+ exited Config::BEGIN
+ Package lib/Config.pm.
+ entering Config::TIEHASH
+ exited Config::TIEHASH
+ entering Exporter::import
+ entering Exporter::export
+ exited Exporter::export
+ exited Exporter::import
+ exited main::BEGIN
+ entering Config::myconfig
+ entering Config::FETCH
+ exited Config::FETCH
+ entering Config::FETCH
+ exited Config::FETCH
+ entering Config::FETCH
+
+=item 4
+
+ in $=main::BEGIN() from /dev/null:0
+ in $=Config::BEGIN() from lib/Config.pm:2
+ Package lib/Exporter.pm.
+ Package lib/Carp.pm.
+ Package lib/Config.pm.
+ in $=Config::TIEHASH('Config') from lib/Config.pm:644
+ in $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0
+ in $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from li
+ in @=Config::myconfig() from /dev/null:0
+ in $=Config::FETCH(ref(Config), 'package') from lib/Config.pm:574
+ in $=Config::FETCH(ref(Config), 'baserev') from lib/Config.pm:574
+ in $=Config::FETCH(ref(Config), 'PERL_VERSION') from lib/Config.pm:574
+ in $=Config::FETCH(ref(Config), 'PERL_SUBVERSION') from lib/Config.pm:574
+ in $=Config::FETCH(ref(Config), 'osname') from lib/Config.pm:574
+ in $=Config::FETCH(ref(Config), 'osvers') from lib/Config.pm:574
+
+=item 6
+
+ in $=main::BEGIN() from /dev/null:0
+ in $=Config::BEGIN() from lib/Config.pm:2
+ Package lib/Exporter.pm.
+ Package lib/Carp.pm.
+ out $=Config::BEGIN() from lib/Config.pm:0
+ Package lib/Config.pm.
+ in $=Config::TIEHASH('Config') from lib/Config.pm:644
+ out $=Config::TIEHASH('Config') from lib/Config.pm:644
+ in $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0
+ in $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/
+ out $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/
+ out $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0
+ out $=main::BEGIN() from /dev/null:0
+ in @=Config::myconfig() from /dev/null:0
+ in $=Config::FETCH(ref(Config), 'package') from lib/Config.pm:574
+ out $=Config::FETCH(ref(Config), 'package') from lib/Config.pm:574
+ in $=Config::FETCH(ref(Config), 'baserev') from lib/Config.pm:574
+ out $=Config::FETCH(ref(Config), 'baserev') from lib/Config.pm:574
+ in $=Config::FETCH(ref(Config), 'PERL_VERSION') from lib/Config.pm:574
+ out $=Config::FETCH(ref(Config), 'PERL_VERSION') from lib/Config.pm:574
+ in $=Config::FETCH(ref(Config), 'PERL_SUBVERSION') from lib/Config.pm:574
+
+=item 14
+
+ in $=main::BEGIN() from /dev/null:0
+ in $=Config::BEGIN() from lib/Config.pm:2
+ Package lib/Exporter.pm.
+ Package lib/Carp.pm.
+ out $=Config::BEGIN() from lib/Config.pm:0
+ Package lib/Config.pm.
+ in $=Config::TIEHASH('Config') from lib/Config.pm:644
+ out $=Config::TIEHASH('Config') from lib/Config.pm:644
+ in $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0
+ in $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/E
+ out $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/E
+ out $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0
+ out $=main::BEGIN() from /dev/null:0
+ in @=Config::myconfig() from /dev/null:0
+ in $=Config::FETCH('Config=HASH(0x1aa444)', 'package') from lib/Config.pm:574
+ out $=Config::FETCH('Config=HASH(0x1aa444)', 'package') from lib/Config.pm:574
+ in $=Config::FETCH('Config=HASH(0x1aa444)', 'baserev') from lib/Config.pm:574
+ out $=Config::FETCH('Config=HASH(0x1aa444)', 'baserev') from lib/Config.pm:574
+
+=item 30
+
+ in $=CODE(0x15eca4)() from /dev/null:0
+ in $=CODE(0x182528)() from lib/Config.pm:2
+ Package lib/Exporter.pm.
+ out $=CODE(0x182528)() from lib/Config.pm:0
+ scalar context return from CODE(0x182528): undef
+ Package lib/Config.pm.
+ in $=Config::TIEHASH('Config') from lib/Config.pm:628
+ out $=Config::TIEHASH('Config') from lib/Config.pm:628
+ scalar context return from Config::TIEHASH: empty hash
+ in $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0
+ in $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/Exporter.pm:171
+ out $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/Exporter.pm:171
+ scalar context return from Exporter::export: ''
+ out $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0
+ scalar context return from Exporter::import: ''
+
+=back
+
+In all cases shown above, the line indentation shows the call tree.
+If bit 2 of C<frame> is set, a line is printed on exit from a
+subroutine as well. If bit 4 is set, the arguments are printed
+along with the caller info. If bit 8 is set, the arguments are
+printed even if they are tied or references. If bit 16 is set, the
+return value is printed, too.
+
+When a package is compiled, a line like this
+
+ Package lib/Carp.pm.
+
+is printed with proper indentation.
+
+=head1 Debugging regular expressions
+
+There are two ways to enable debugging output for regular expressions.
+
+If your perl is compiled with C<-DDEBUGGING>, you may use the
+B<-Dr> flag on the command line.
+
+Otherwise, one can C<use re 'debug'>, which has effects at
+compile time and run time. It is not lexically scoped.
+
+=head2 Compile-time output
+
+The debugging output at compile time looks like this:
+
+ compiling RE `[bc]d(ef*g)+h[ij]k$'
+ size 43 first at 1
+ 1: ANYOF(11)
+ 11: EXACT <d>(13)
+ 13: CURLYX {1,32767}(27)
+ 15: OPEN1(17)
+ 17: EXACT <e>(19)
+ 19: STAR(22)
+ 20: EXACT <f>(0)
+ 22: EXACT <g>(24)
+ 24: CLOSE1(26)
+ 26: WHILEM(0)
+ 27: NOTHING(28)
+ 28: EXACT <h>(30)
+ 30: ANYOF(40)
+ 40: EXACT <k>(42)
+ 42: EOL(43)
+ 43: END(0)
+ anchored `de' at 1 floating `gh' at 3..2147483647 (checking floating)
+ stclass `ANYOF' minlen 7
+
+The first line shows the pre-compiled form of the regex. The second
+shows the size of the compiled form (in arbitrary units, usually
+4-byte words) and the label I<id> of the first node that does a
+match.
+
+The last line (split into two lines above) contains optimizer
+information. In the example shown, the optimizer found that the match
+should contain a substring C<de> at offset 1, plus substring C<gh>
+at some offset between 3 and infinity. Moreover, when checking for
+these substrings (to abandon impossible matches quickly), Perl will check
+for the substring C<gh> before checking for the substring C<de>. The
+optimizer may also use the knowledge that the match starts (at the
+C<first> I<id>) with a character class, and the match cannot be
+shorter than 7 chars.
+
+The fields of interest which may appear in the last line are
+
+=over
+
+=item C<anchored> I<STRING> C<at> I<POS>
+
+=item C<floating> I<STRING> C<at> I<POS1..POS2>
+
+See above.
+
+=item C<matching floating/anchored>
+
+Which substring to check first.
+
+=item C<minlen>
+
+The minimal length of the match.
+
+=item C<stclass> I<TYPE>
+
+Type of first matching node.
+
+=item C<noscan>
+
+Don't scan for the found substrings.
+
+=item C<isall>
+
+Means that the optimizer info is all that the regular
+expression contains, and thus one does not need to enter the regex engine at
+all.
+
+=item C<GPOS>
+
+Set if the pattern contains C<\G>.
+
+=item C<plus>
+
+Set if the pattern starts with a repeated char (as in C<x+y>).
+
+=item C<implicit>
+
+Set if the pattern starts with C<.*>.
+
+=item C<with eval>
+
+Set if the pattern contain eval-groups, such as C<(?{ code })> and
+C<(??{ code })>.
+
+=item C<anchored(TYPE)>
+
+If the pattern may match only at a handful of places, (with C<TYPE>
+being C<BOL>, C<MBOL>, or C<GPOS>. See the table below.
+
+=back
+
+If a substring is known to match at end-of-line only, it may be
+followed by C<$>, as in C<floating `k'$>.
+
+The optimizer-specific info is used to avoid entering (a slow) regex
+engine on strings that will not definitely match. If C<isall> flag
+is set, a call to the regex engine may be avoided even when the optimizer
+found an appropriate place for the match.
+
+The rest of the output contains the list of I<nodes> of the compiled
+form of the regex. Each line has format
+
+C< >I<id>: I<TYPE> I<OPTIONAL-INFO> (I<next-id>)
+
+=head2 Types of nodes
+
+Here are the possible types, with short descriptions:
+
+ # TYPE arg-description [num-args] [longjump-len] DESCRIPTION
+
+ # Exit points
+ END no End of program.
+ SUCCEED no Return from a subroutine, basically.
+
+ # Anchors:
+ BOL no Match "" at beginning of line.
+ MBOL no Same, assuming multiline.
+ SBOL no Same, assuming singleline.
+ EOS no Match "" at end of string.
+ EOL no Match "" at end of line.
+ MEOL no Same, assuming multiline.
+ SEOL no Same, assuming singleline.
+ BOUND no Match "" at any word boundary
+ BOUNDL no Match "" at any word boundary
+ NBOUND no Match "" at any word non-boundary
+ NBOUNDL no Match "" at any word non-boundary
+ GPOS no Matches where last m//g left off.
+
+ # [Special] alternatives
+ ANY no Match any one character (except newline).
+ SANY no Match any one character.
+ ANYOF sv Match character in (or not in) this class.
+ ALNUM no Match any alphanumeric character
+ ALNUML no Match any alphanumeric char in locale
+ NALNUM no Match any non-alphanumeric character
+ NALNUML no Match any non-alphanumeric char in locale
+ SPACE no Match any whitespace character
+ SPACEL no Match any whitespace char in locale
+ NSPACE no Match any non-whitespace character
+ NSPACEL no Match any non-whitespace char in locale
+ DIGIT no Match any numeric character
+ NDIGIT no Match any non-numeric character
+
+ # BRANCH The set of branches constituting a single choice are hooked
+ # together with their "next" pointers, since precedence prevents
+ # anything being concatenated to any individual branch. The
+ # "next" pointer of the last BRANCH in a choice points to the
+ # thing following the whole choice. This is also where the
+ # final "next" pointer of each individual branch points; each
+ # branch starts with the operand node of a BRANCH node.
+ #
+ BRANCH node Match this alternative, or the next...
+
+ # BACK Normal "next" pointers all implicitly point forward; BACK
+ # exists to make loop structures possible.
+ # not used
+ BACK no Match "", "next" ptr points backward.
+
+ # Literals
+ EXACT sv Match this string (preceded by length).
+ EXACTF sv Match this string, folded (prec. by length).
+ EXACTFL sv Match this string, folded in locale (w/len).
+
+ # Do nothing
+ NOTHING no Match empty string.
+ # A variant of above which delimits a group, thus stops optimizations
+ TAIL no Match empty string. Can jump here from outside.
+
+ # STAR,PLUS '?', and complex '*' and '+', are implemented as circular
+ # BRANCH structures using BACK. Simple cases (one character
+ # per match) are implemented with STAR and PLUS for speed
+ # and to minimize recursive plunges.
+ #
+ STAR node Match this (simple) thing 0 or more times.
+ PLUS node Match this (simple) thing 1 or more times.
+
+ CURLY sv 2 Match this simple thing {n,m} times.
+ CURLYN no 2 Match next-after-this simple thing
+ # {n,m} times, set parens.
+ CURLYM no 2 Match this medium-complex thing {n,m} times.
+ CURLYX sv 2 Match this complex thing {n,m} times.
+
+ # This terminator creates a loop structure for CURLYX
+ WHILEM no Do curly processing and see if rest matches.
+
+ # OPEN,CLOSE,GROUPP ...are numbered at compile time.
+ OPEN num 1 Mark this point in input as start of #n.
+ CLOSE num 1 Analogous to OPEN.
+
+ REF num 1 Match some already matched string
+ REFF num 1 Match already matched string, folded
+ REFFL num 1 Match already matched string, folded in loc.
+
+ # grouping assertions
+ IFMATCH off 1 2 Succeeds if the following matches.
+ UNLESSM off 1 2 Fails if the following matches.
+ SUSPEND off 1 1 "Independent" sub-regex.
+ IFTHEN off 1 1 Switch, should be preceded by switcher .
+ GROUPP num 1 Whether the group matched.
+
+ # Support for long regex
+ LONGJMP off 1 1 Jump far away.
+ BRANCHJ off 1 1 BRANCH with long offset.
+
+ # The heavy worker
+ EVAL evl 1 Execute some Perl code.
+
+ # Modifiers
+ MINMOD no Next operator is not greedy.
+ LOGICAL no Next opcode should set the flag only.
+
+ # This is not used yet
+ RENUM off 1 1 Group with independently numbered parens.
+
+ # This is not really a node, but an optimized away piece of a "long" node.
+ # To simplify debugging output, we mark it as if it were a node
+ OPTIMIZED off Placeholder for dump.
+
+=head2 Run-time output
+
+First of all, when doing a match, one may get no run-time output even
+if debugging is enabled. This means that the regex engine was never
+entered and that all of the job was therefore done by the optimizer.
+
+If the regex engine was entered, the output may look like this:
+
+ Matching `[bc]d(ef*g)+h[ij]k$' against `abcdefg__gh__'
+ Setting an EVAL scope, savestack=3
+ 2 <ab> <cdefg__gh_> | 1: ANYOF
+ 3 <abc> <defg__gh_> | 11: EXACT <d>
+ 4 <abcd> <efg__gh_> | 13: CURLYX {1,32767}
+ 4 <abcd> <efg__gh_> | 26: WHILEM
+ 0 out of 1..32767 cc=effff31c
+ 4 <abcd> <efg__gh_> | 15: OPEN1
+ 4 <abcd> <efg__gh_> | 17: EXACT <e>
+ 5 <abcde> <fg__gh_> | 19: STAR
+ EXACT <f> can match 1 times out of 32767...
+ Setting an EVAL scope, savestack=3
+ 6 <bcdef> <g__gh__> | 22: EXACT <g>
+ 7 <bcdefg> <__gh__> | 24: CLOSE1
+ 7 <bcdefg> <__gh__> | 26: WHILEM
+ 1 out of 1..32767 cc=effff31c
+ Setting an EVAL scope, savestack=12
+ 7 <bcdefg> <__gh__> | 15: OPEN1
+ 7 <bcdefg> <__gh__> | 17: EXACT <e>
+ restoring \1 to 4(4)..7
+ failed, try continuation...
+ 7 <bcdefg> <__gh__> | 27: NOTHING
+ 7 <bcdefg> <__gh__> | 28: EXACT <h>
+ failed...
+ failed...
+
+The most significant information in the output is about the particular I<node>
+of the compiled regex that is currently being tested against the target string.
+The format of these lines is
+
+C< >I<STRING-OFFSET> <I<PRE-STRING>> <I<POST-STRING>> |I<ID>: I<TYPE>
+
+The I<TYPE> info is indented with respect to the backtracking level.
+Other incidental information appears interspersed within.
+
+=head1 Debugging Perl memory usage
+
+Perl is a profligate wastrel when it comes to memory use. There
+is a saying that to estimate memory usage of Perl, assume a reasonable
+algorithm for memory allocation, multiply that estimate by 10, and
+while you still may miss the mark, at least you won't be quite so
+astonished. This is not absolutely true, but may prvide a good
+grasp of what happens.
+
+Assume that an integer cannot take less than 20 bytes of memory, a
+float cannot take less than 24 bytes, a string cannot take less
+than 32 bytes (all these examples assume 32-bit architectures, the
+result are quite a bit worse on 64-bit architectures). If a variable
+is accessed in two of three different ways (which require an integer,
+a float, or a string), the memory footprint may increase yet another
+20 bytes. A sloppy malloc(3) implementation can make inflate these
+numbers dramatically.
+
+On the opposite end of the scale, a declaration like
+
+ sub foo;
+
+may take up to 500 bytes of memory, depending on which release of Perl
+you're running.
+
+Anecdotal estimates of source-to-compiled code bloat suggest an
+eightfold increase. This means that the compiled form of reasonable
+(normally commented, properly indented etc.) code will take
+about eight times more space in memory than the code took
+on disk.
+
+There are two Perl-specific ways to analyze memory usage:
+$ENV{PERL_DEBUG_MSTATS} and B<-DL> command-line switch. The first
+is available only if Perl is compiled with Perl's malloc(); the
+second only if Perl was built with C<-DDEBUGGING>. See the
+instructions for how to do this in the F<INSTALL> podpage at
+the top level of the Perl source tree.
+
+=head2 Using C<$ENV{PERL_DEBUG_MSTATS}>
+
+If your perl is using Perl's malloc() and was compiled with the
+necessary switches (this is the default), then it will print memory
+usage statistics after compiling your code hwen C<< $ENV{PERL_DEBUG_MSTATS}
+> 1 >>, and before termination of the program when C<<
+$ENV{PERL_DEBUG_MSTATS} >= 1 >>. The report format is similar to
+the following example:
+
+ $ PERL_DEBUG_MSTATS=2 perl -e "require Carp"
+ Memory allocation statistics after compilation: (buckets 4(4)..8188(8192)
+ 14216 free: 130 117 28 7 9 0 2 2 1 0 0
+ 437 61 36 0 5
+ 60924 used: 125 137 161 55 7 8 6 16 2 0 1
+ 74 109 304 84 20
+ Total sbrk(): 77824/21:119. Odd ends: pad+heads+chain+tail: 0+636+0+2048.
+ Memory allocation statistics after execution: (buckets 4(4)..8188(8192)
+ 30888 free: 245 78 85 13 6 2 1 3 2 0 1
+ 315 162 39 42 11
+ 175816 used: 265 176 1112 111 26 22 11 27 2 1 1
+ 196 178 1066 798 39
+ Total sbrk(): 215040/47:145. Odd ends: pad+heads+chain+tail: 0+2192+0+6144.
+
+It is possible to ask for such a statistic at arbitrary points in
+your execution using the mstats() function out of the standard
+Devel::Peek module.
+
+Here is some explanation of that format:
+
+=over
+
+=item C<buckets SMALLEST(APPROX)..GREATEST(APPROX)>
+
+Perl's malloc() uses bucketed allocations. Every request is rounded
+up to the closest bucket size available, and a bucket is taken from
+the pool of buckets of that size.
+
+The line above describes the limits of buckets currently in use.
+Each bucket has two sizes: memory footprint and the maximal size
+of user data that can fit into this bucket. Suppose in the above
+example that the smallest bucket were size 4. The biggest bucket
+would have usable size 8188, and the memory footprint would be 8192.
+
+In a Perl built for debugging, some buckets may have negative usable
+size. This means that these buckets cannot (and will not) be used.
+For larger buckets, the memory footprint may be one page greater
+than a power of 2. If so, case the corresponding power of two is
+printed in the C<APPROX> field above.
+
+=item Free/Used
+
+The 1 or 2 rows of numbers following that correspond to the number
+of buckets of each size between C<SMALLEST> and C<GREATEST>. In
+the first row, the sizes (memory footprints) of buckets are powers
+of two--or possibly one page greater. In the second row, if present,
+the memory footprints of the buckets are between the memory footprints
+of two buckets "above".
+
+For example, suppose under the pervious example, the memory footprints
+were
+
+ free: 8 16 32 64 128 256 512 1024 2048 4096 8192
+ 4 12 24 48 80
+
+With non-C<DEBUGGING> perl, the buckets starting from C<128> have
+a 4-byte overhead, and thus a 8192-long bucket may take up to
+8188-byte allocations.
+
+=item C<Total sbrk(): SBRKed/SBRKs:CONTINUOUS>
+
+The first two fields give the total amount of memory perl sbrk(2)ed
+(ess-broken? :-) and number of sbrk(2)s used. The third number is
+what perl thinks about continuity of returned chunks. So long as
+this number is positive, malloc() will assume that it is probable
+that sbrk(2) will provide continuous memory.
+
+Memory allocated by external libraries is not counted.
+
+=item C<pad: 0>
+
+The amount of sbrk(2)ed memory needed to keep buckets aligned.
+
+=item C<heads: 2192>
+
+Although memory overhead of bigger buckets is kept inside the bucket, for
+smaller buckets, it is kept in separate areas. This field gives the
+total size of these areas.
+
+=item C<chain: 0>
+
+malloc() may want to subdivide a bigger bucket into smaller buckets.
+If only a part of the deceased bucket is left unsubdivided, the rest
+is kept as an element of a linked list. This field gives the total
+size of these chunks.
+
+=item C<tail: 6144>
+
+To minimize the number of sbrk(2)s, malloc() asks for more memory. This
+field gives the size of the yet unused part, which is sbrk(2)ed, but
+never touched.
+
+=back
+
+=head2 Example of using B<-DL> switch
+
+Below we show how to analyse memory usage by
+
+ do 'lib/auto/POSIX/autosplit.ix';
+
+The file in question contains a header and 146 lines similar to
+
+ sub getcwd;
+
+B<WARNING>: The discussion below supposes 32-bit architecture. In
+newer releases of Perl, memory usage of the constructs discussed
+here is greatly improved, but the story discussed below is a real-life
+story. This story is mercilessly terse, and assumes rather more than cursory
+knowledge of Perl internals. Type space to continue, `q' to quit.
+(Actually, you just want to skip to the next section.)
+
+Here is the itemized list of Perl allocations performed during parsing
+of this file:
+
+ !!! "after" at test.pl line 3.
+ Id subtot 4 8 12 16 20 24 28 32 36 40 48 56 64 72 80 80+
+ 0 02 13752 . . . . 294 . . . . . . . . . . 4
+ 0 54 5545 . . 8 124 16 . . . 1 1 . . . . . 3
+ 5 05 32 . . . . . . . 1 . . . . . . . .
+ 6 02 7152 . . . . . . . . . . 149 . . . . .
+ 7 02 3600 . . . . . 150 . . . . . . . . . .
+ 7 03 64 . -1 . 1 . . 2 . . . . . . . . .
+ 7 04 7056 . . . . . . . . . . . . . . . 7
+ 7 17 38404 . . . . . . . 1 . . 442 149 . . 147 .
+ 9 03 2078 17 249 32 . . . . 2 . . . . . . . .
+
+
+To see this list, insert two C<warn('!...')> statements around the call:
+
+ warn('!');
+ do 'lib/auto/POSIX/autosplit.ix';
+ warn('!!! "after"');
+
+and run it with PErl's B<-DL> option. The first warn() will print
+memory allocation info before parsing the file and will memorize
+the statistics at this point (we ignore what it prints). The second
+warn() prints increments with respect to these memorized data. This
+is the printout shown above.
+
+Different I<Id>s on the left correspond to different subsystems of
+the perl interpreter. They are just the first argument given to
+the perl memory allocation API named New(). To find what C<9 03>
+means, just B<grep> the perl source for C<903>. You'll find it in
+F<util.c>, function savepvn(). (I know, you wonder why we told you
+to B<grep> and then gave away the answer. That's because grepping
+the source is good for the soul.) This function is used to store
+a copy of an existing chunk of memory. Using a C debugger, one can
+see that the function was called either directly from gv_init() or
+via sv_magic(), and that gv_init() is called from gv_fetchpv()--which
+was itself called from newSUB(). Please stop to catch your breath now.
+
+B<NOTE>: To reach this point in the debugger and skip the calls to
+savepvn() during the compilation of the main program, you should
+set a C breakpoint
+in Perl_warn(), continue until this point is reached, and I<then> set
+a C breakpoint in Perl_savepvn(). Note that you may need to skip a
+handful of Perl_savepvn() calls that do not correspond to mass production
+of CVs (there are more C<903> allocations than 146 similar lines of
+F<lib/auto/POSIX/autosplit.ix>). Note also that C<Perl_> prefixes are
+added by macroization code in perl header files to avoid conflicts
+with external libraries.
+
+Anyway, we see that C<903> ids correspond to creation of globs, twice
+per glob - for glob name, and glob stringification magic.
+
+Here are explanations for other I<Id>s above:
+
+=over
+
+=item C<717>
+
+CReates bigger C<XPV*> structures. In the case above, it
+creates 3 C<AV>s per subroutine, one for a list of lexical variable
+names, one for a scratchpad (which contains lexical variables and
+C<targets>), and one for the array of scratchpads needed for
+recursion.
+
+It also creates a C<GV> and a C<CV> per subroutine, all called from
+start_subparse().
+
+=item C<002>
+
+Creates a C array corresponding to the C<AV> of scratchpads and the
+scratchpad itself. The first fake entry of this scratchpad is
+created though the subroutine itself is not defined yet.
+
+It also creates C arrays to keep data for the stash. This is one HV,
+but it grows; thus, there are 4 big allocations: the big chunks are not
+freed, but are kept as additional arenas for C<SV> allocations.
+
+=item C<054>
+
+Creates a C<HEK> for the name of the glob for the subroutine. This
+name is a key in a I<stash>.
+
+Big allocations with this I<Id> correspond to allocations of new
+arenas to keep C<HE>.
+
+=item C<602>
+
+Creates a C<GP> for the glob for the subroutine.
+
+=item C<702>
+
+Creates the C<MAGIC> for the glob for the subroutine.
+
+=item C<704>
+
+Creates I<arenas> which keep SVs.
+
+=back
+
+=head2 B<-DL> details
+
+If Perl is run with B<-DL> option, then warn()s that start with `!'
+behave specially. They print a list of I<categories> of memory
+allocations, and statistics of allocations of different sizes for
+these categories.
+
+If warn() string starts with
+
+=over
+
+=item C<!!!>
+
+print changed categories only, print the differences in counts of allocations.
+
+=item C<!!>
+
+print grown categories only; print the absolute values of counts, and totals.
+
+=item C<!>
+
+print nonempty categories, print the absolute values of counts and totals.
+
+=back
+
+=head2 Limitations of B<-DL> statistics
+
+If an extension or external library does not use the Perl API to
+allocate memory, such allocations are not counted.
+
+=head1 SEE ALSO
+
+L<perldebug>,
+L<perlguts>,
+L<perlrun>
+L<re>,
+and
+L<Devel::Dprof>.
=head1 The Perl Debugger
-"As soon as we started programming, we found to our
-surprise that it wasn't as easy to get programs right
-as we had thought. Debugging had to be discovered.
-I can remember the exact instant when I realized that
-a large part of my life from then on was going to be
-spent in finding mistakes in my own programs."
-
-I< --Maurice Wilkes, 1949>
-
If you invoke Perl with the B<-d> switch, your script runs under the
Perl source debugger. This works like an interactive Perl
environment, prompting for debugger commands that let you examine
the debugger all by itself just to test out Perl constructs
interactively to see what they do. For example:
- perl -d -e 42
+ $ perl -d -e 42
-In Perl, the debugger is not a separate program as it usually is in the
+In Perl, the debugger is not a separate program the way it usually is in the
typical compiled environment. Instead, the B<-d> flag tells the compiler
to insert source information into the parse trees it's about to hand off
to the interpreter. That means your code must first compile correctly
for the debugger to work on it. Then when the interpreter starts up, it
-preloads a Perl library file containing the debugger itself.
+preloads a special Perl library file containing the debugger.
The program will halt I<right before> the first run-time executable
statement (but see below regarding compile-time statements) and ask you
line it's I<about> to execute, rather than the one it has just executed.
Any command not recognized by the debugger is directly executed
-(C<eval>'d) as Perl code in the current package. (The debugger uses the
-DB package for its own state information.)
+(C<eval>'d) as Perl code in the current package. (The debugger
+uses the DB package for keeping its own state information.)
-Leading white space before a command would cause the debugger to think
-it's I<NOT> a debugger command but for Perl, so be careful not to do
-that.
+For any text entered at the debugger prompt, leading and trailing whitespace
+is first stripped before further processing. If a debugger command
+coincides with some function in your own program, merely precede the
+function with something that doesn't look like a debugger command, such
+as a leading C<;> or perhaps a C<+>, or by wrapping it with parentheses
+or braces.
=head2 Debugger Commands
together on one screen.
If the output of the C<h> command (or any command, for that matter) scrolls
-past your screen, either precede the command with a leading pipe symbol so
-it's run through your pager, as in
+past your screen, precede the command with a leading pipe symbol so
+that it's run through your pager, as in
DB> |h
Evaluates its expression in list context and dumps out the result
in a pretty-printed fashion. Nested data structures are printed out
-recursively, unlike the C<print> function.
+recursively, unlike the real C<print> function in Perl.
+See L<Dumpvalue> if you'd like to do this yourself.
-The details of printout are governed by multiple C<O>ptions.
+The output format is governed by multiple options described under
+L<"Options">.
=item V [pkg [vars]]
-Display all (or some) variables in package (defaulting to the C<main>
-package) using a data pretty-printer (hashes show their keys and values so
-you see what's what, control characters are made printable, etc.). Make
-sure you don't put the type specifier (like C<$>) there, just the symbol
-names, like this:
+Display all (or some) variables in package (defaulting to C<main>)
+using a data pretty-printer (hashes show their keys and values so
+you see what's what, control characters are made printable, etc.).
+Make sure you don't put the type specifier (like C<$>) there, just
+the symbol names, like this:
V DB filename line
-Use C<~pattern> and C<!pattern> for positive and negative regexps.
-
-Nested data structures are printed out in a legible fashion, unlike
-the C<print> function.
+Use C<~pattern> and C<!pattern> for positive and negative regexes.
-The details of printout are governed by multiple C<O>ptions.
+This is similar to calling the C<x> command on each applicable var.
=item X [vars]
=item s [expr]
-Single step. Executes until it reaches the beginning of another
+Single step. Executes until the beginning of another
statement, descending into subroutine calls. If an expression is
supplied that includes function calls, it too will be single-stepped.
=item n [expr]
-Next. Executes over subroutine calls, until it reaches the beginning
+Next. Executes over subroutine calls, until the beginning
of the next statement. If an expression is supplied that includes
function calls, those functions will be executed with stops before
each statement.
=item r
-Continue until return from the current subroutine. Dump the return
-value, if the PrintRet option is set (default).
+Continue until the return from the current subroutine.
+Dump the return value if the C<PrintRet> option is set (default).
=item <CR>
=item l subname
List first window of lines from subroutine. I<subname> may
-be a variable which contains a code reference.
+be a variable that contains a code reference.
=item -
=item .
-Return debugger pointer to the last-executed line and
-print it out.
+Return the internal debugger pointer to the line last
+executed, and print out that line.
=item f filename
-Switch to viewing a different file or eval statement. If C<filename>
-is not a full filename as found in values of %INC, it is considered as
-a regexp.
+Switch to viewing a different file or C<eval> statement. If I<filename>
+is not a full pathname found in the values of %INC, it is considered
+a regex.
C<eval>ed strings (when accessible) are considered to be filenames:
C<f (eval 7)> and C<f eval 7\b> access the body of the 7th C<eval>ed string
-(in the order of execution). The bodies of currently executed C<eval>
-and of C<eval>ed strings which define subroutines are saved, thus are
-accessible by this mechanism.
+(in the order of execution). The bodies of the currently executed C<eval>
+and of C<eval>ed strings that define subroutines are saved and thus
+accessible.
=item /pattern/
-Search forwards for pattern; final / is optional.
+Search forwards for pattern (a Perl regex); final / is optional.
=item ?pattern?
List all breakpoints and actions.
-=item S [[!]pattern]
+=item S [[!]regex]
-List subroutine names [not] matching pattern.
+List subroutine names [not] matching the regex.
=item t
-Toggle trace mode (see also C<AutoTrace> C<O>ption).
+Toggle trace mode (see also the C<AutoTrace> option).
=item t expr
-Trace through execution of expr. For example:
-
- $ perl -de 42
- Stack dump during die enabled outside of evals.
-
- Loading DB routines from perl5db.pl patch level 0.94
- Emacs support available.
-
- Enter h or `h h' for help.
-
- main::(-e:1): 0
- DB<1> sub foo { 14 }
-
- DB<2> sub bar { 3 }
-
- DB<3> t print foo() * bar()
- main::((eval 172):3): print foo() + bar();
- main::foo((eval 168):2):
- main::bar((eval 170):2):
- 42
-
-or, with the C<O>ption C<frame=2> set,
-
- DB<4> O f=2
- frame = '2'
- DB<5> t print foo() * bar()
- 3: foo() * bar()
- entering main::foo
- 2: sub foo { 14 };
- exited main::foo
- entering main::bar
- 2: sub bar { 3 };
- exited main::bar
- 42
+Trace through execution of C<expr>.
+See L<perldebguts/"Frame Listing Output Examples"> for examples.
=item b [line] [condition]
-Set a breakpoint. If line is omitted, sets a breakpoint on the line
-that is about to be executed. If a condition is specified, it's
-evaluated each time the statement is reached and a breakpoint is taken
-only if the condition is true. Breakpoints may be set on only lines
-that begin an executable statement. Conditions don't use B<if>:
+Set a breakpoint before the given line. If I<line> is omitted, set a
+breakpoint on the line about to be executed. If a condition
+is specified, it's evaluated each time the statement is reached: a
+breakpoint is taken only if the condition is true. Breakpoints may
+only be set on lines that begin an executable statement. Conditions
+don't use B<if>:
b 237 $x > 30
b 237 ++$count237 < 11
=item b subname [condition]
-Set a breakpoint at the first line of the named subroutine. I<subname> may
-be a variable which contains a code reference (in this case I<condition>
+Set a breakpoint before the first line of the named subroutine. I<subname> may
+be a variable containing a code reference (in this case I<condition>
is not supported).
=item b postpone subname [condition]
-Set breakpoint at first line of subroutine after it is compiled.
+Set a breakpoint at first line of subroutine after it is compiled.
=item b load filename
-Set breakpoint at the first executed line of the file. Filename should
-be a full name as found in values of %INC.
+Set a breakpoint before the first executed line of the I<filename>,
+which should be a full pathname found amongst the %INC values.
=item b compile subname
-Sets breakpoint at the first statement executed after the subroutine
-is compiled.
+Sets a breakpoint before the first statement executed after the specified
+subroutine is compiled.
=item d [line]
-Delete a breakpoint at the specified line. If line is omitted, deletes
-the breakpoint on the line that is about to be executed.
+Delete a breakpoint from the specified I<line>. If I<line> is omitted, deletes
+the breakpoint from the line about to be executed.
=item D
=item a [line] command
-Set an action to be done before the line is executed. If line is
-omitted, sets an action on the line that is about to be executed.
+Set an action to be done before the line is executed. If I<line> is
+omitted, set an action on the line about to be executed.
The sequence of steps taken by the debugger is
1. check for a breakpoint at this line
=item a [line]
-Delete an action at the specified line. If line is omitted, deletes
+Delete an action from the specified line. If I<line> is omitted, delete
the action on the line that is about to be executed.
=item A
Delete all installed actions.
-=item W [expr]
+=item W expr
-Add a global watch-expression.
+Add a global watch-expression. We hope you know what one of these
+is, because they're supposed to be obvious. B<WARNING>: It is far
+too easy to destroy your watch expressions by accidentally omitting
+the I<expr>.
=item W
Delete all watch-expressions.
-=item O [opt[=val]] [opt"val"] [opt?]...
+=item O booloption ...
+
+Set each listed Boolean option to the value C<1>.
+
+=item O anyoption? ...
+
+Print out the value of one or more options.
+
+=item O option=value ...
+
+Set the value of one or more options. If the value has internal
+whitespace, it should be quoted. For example, you could set C<O
+pager="less -MQeicsNfr"> to call B<less> with those specific options.
+You may use either single or double quotes, but if you do, you must
+escape any embedded instances of same sort of quote you began with,
+as well as any escaping any escapes that immediately precede that
+quote but which are not meant to escape the quote itself. In other
+words, you follow single-quoting rules irrespective of the quote;
+eg: C<O option='this isn\'t bad'> or C<O option="She said, \"Isn't
+it?\"">.
+
+For historical reasons, the C<=value> is optional, but defaults to
+1 only where it is safe to do so--that is, mostly for Boolean
+options. It is always better to assign a specific value using C<=>.
+The C<option> can be abbreviated, but for clarity probably should
+not be. Several options can be set together. See L<"Options"> for
+a list of these.
+
+=item < ?
+
+List out all pre-prompt Perl command actions.
+
+=item < [ command ]
+
+Set an action (Perl command) to happen before every debugger prompt.
+A multi-line command may be entered by backslashing the newlines.
+B<WARNING> If C<command> is missing, all actions are wiped out!
+
+=item << command
+
+Add an action (Perl command) to happen before every debugger prompt.
+A multi-line command may be entered by backwhacking the newlines.
+
+=item > ?
+
+List out post-prompt Perl command actions.
+
+=item > command
+
+Set an action (Perl command) to happen after the prompt when you've
+just given a command to return to executing the script. A multi-line
+command may be entered by backslashing the newlines (we bet you
+couldn't've guessed this by now). B<WARNING> If C<command> is
+missing, all actions are wiped out!
+
+=item >> command
+
+Adds an action (Perl command) to happen after the prompt when you've
+just given a command to return to executing the script. A multi-line
+command may be entered by slackbashing the newlines.
+
+=item { ?
+
+List out pre-prompt debugger commands.
+
+=item { [ command ]
+
+Set an action (debugger command) to happen before every debugger prompt.
+A multi-line command may be entered in the customary fashion.
+B<WARNING> If C<command> is missing, all actions are wiped out!
+
+Because this command is in some senses new, a warning is issued if
+you appear to have accidentally entered a block instead. If that's
+what you mean to do, write it as with C<;{ ... }> or even
+C<do { ... }>.
+
+=item {{ command
+
+Add an action (debugger command) to happen before every debugger prompt.
+A multi-line command may be entered, if you can guess how: see above.
+
+=item ! number
+
+Redo a previous command (defaults to the previous command).
+
+=item ! -number
+
+Redo number'th previous command.
+
+=item ! pattern
+
+Redo last command that started with pattern.
+See C<O recallCommand>, too.
+
+=item !! cmd
+
+Run cmd in a subprocess (reads from DB::IN, writes to DB::OUT) See
+C<O shellBang>, also. Note that the user's current shell (well,
+their C<$ENV{SHELL}> variable) will be used, which can interfere
+with proper interpretation of exit status or signal and coredump
+information.
+
+=item H -number
+
+Display last n commands. Only commands longer than one character are
+listed. If I<number> is omitted, list them all.
+
+=item q or ^D
+
+Quit. ("quit" doesn't work for this, unless you've made an alias)
+This is the only supported way to exit the debugger, though typing
+C<exit> twice might work.
+
+Set the C<inhibit_exit> option to 0 if you want to be able to step
+off the end the script. You may also need to set $finished to 0
+if you want to step through global destruction.
+
+=item R
+
+Restart the debugger by C<exec()>ing a new session. We try to maintain
+your history across this, but internal settings and command-line options
+may be lost.
+
+The following setting are currently preserved: history, breakpoints,
+actions, debugger options, and the Perl command-line
+options B<-w>, B<-I>, and B<-e>.
+
+=item |dbcmd
+
+Run the debugger command, piping DB::OUT into your current pager.
+
+=item ||dbcmd
+
+Same as C<|dbcmd> but DB::OUT is temporarily B<select>ed as well.
+
+=item = [alias value]
+
+Define a command alias, like
+
+ = quit q
+
+or list current aliases.
+
+=item command
+
+Execute command as a Perl statement. A trailing semicolon will be
+supplied. If the Perl statement would otherwise be confused for a
+Perl debugger, use a leading semicolon, too.
+
+=item m expr
+
+List which methods may be called on the result of the evaluated
+expression. The expression may evaluated to a reference to a
+blessed object, or to a package name.
+
+=item man [manpage]
+
+Despite its name, this calls your system's default documentation
+viewer on the given page, or on the viewer itself if I<manpage> is
+omitted. If that viewer is B<man>, the current C<Config> information
+is used to invoke B<man> using the proper MANPATH or S<B<-M>
+I<manpath>> option. Failed lookups of the form C<XXX> that match
+known manpages of the form I<perlXXX> will be retried. This lets
+you type C<man debug> or C<man op> from the debugger.
+
+On systems traditionally bereft of a usable B<man> command, the
+debugger invokes B<perldoc>. Occasionally this determination is
+incorrect due to recalcitrant vendors or rather more felicitously,
+to enterprising users. If you fall into either category, just
+manually set the $DB::doccmd variable to whatever viewer to view
+the Perl documentation on your system. This may be set in an rc
+file, or through direct assignment. We're still waiting for a
+working example of something along the lines of:
-Set or query values of options. val defaults to 1. opt can
-be abbreviated. Several options can be listed.
+ $DB::doccmd = 'netscape -remote http://something.here/';
+
+=back
+
+=head2 Configurable Options
+
+The debugger has numerous options settable using the C<O> command,
+either interactively or from the environment or an rc file.
=over 12
=item C<recallCommand>, C<ShellBang>
The characters used to recall command or spawn shell. By
-default, these are both set to C<!>.
+default, both are set to C<!>, which is unfortunate.
=item C<pager>
-Program to use for output of pager-piped commands (those
-beginning with a C<|> character.) By default,
-C<$ENV{PAGER}> will be used.
+Program to use for output of pager-piped commands (those beginning
+with a C<|> character.) By default, C<$ENV{PAGER}> will be used.
+Because the debugger uses your current terminal characteristics
+for bold and underlining, if the chosen pager does not pass escape
+sequences through unchanged, the output of some debugger commands
+will not be readable when sent through the pager.
=item C<tkRunning>
=item C<signalLevel>, C<warnLevel>, C<dieLevel>
-Level of verbosity. By default the debugger is in a sane verbose mode,
-thus it will print backtraces on all the warnings and die-messages
-which are going to be printed out, and will print a message when
-interesting uncaught signals arrive.
+Level of verbosity. By default, the debugger prints backtraces
+upon receiving any kind of warning (this is often annoying) and
+fatal exceptions (this is often valuable). It will attempt to print
+a message when uncaught INT, BUS, or SEGV signals arrive.
-To disable this behaviour, set these values to 0. If C<dieLevel> is 2,
-then the messages which will be caught by surrounding C<eval> are also
-printed.
+To disable this behaviour, set these values to 0. If C<dieLevel>
+is 2, the debugger usurps your own exception handler and prints out
+a trace of these, replacing your exceptions with its own. This may
+be useful for some tracing purposes, but tends to hopelessly destroy
+any program that takes its exception handling seriously.
=item C<AutoTrace>
=item C<LineInfo>
File or pipe to print line number info to. If it is a pipe (say,
-C<|visual_perl_db>), then a short, "emacs like" message is used.
+C<|visual_perl_db>), then a short message is used. This is the
+mechanism used to interact with a slave editor or visual debugger,
+such as the special C<vi> or C<emacs> hooks, or the C<ddd> graphical
+debugger.
=item C<inhibit_exit>
=item C<ornaments>
-affects screen appearance of the command line (see L<Term::ReadLine>).
+Affects screen appearance of the command line (see L<Term::ReadLine>).
+There is currently no way to disable these, which can render
+some output illegible on some displays, or with some pagers.
+This is considered a bug.
=item C<frame>
-affects printing messages on entry and exit from subroutines. If
+Affects the printing of messages upon entry and exit from subroutines. If
C<frame & 2> is false, messages are printed on entry only. (Printing
-on exit may be useful if inter(di)spersed with other messages.)
+on exit might be useful if interspersed with other messages.)
-If C<frame & 4>, arguments to functions are printed as well as the
-context and caller info. If C<frame & 8>, overloaded C<stringify> and
-C<tie>d C<FETCH> are enabled on the printed arguments. If C<frame &
-16>, the return value from the subroutine is printed as well.
+If C<frame & 4>, arguments to functions are printed, plus context
+and caller info. If C<frame & 8>, overloaded C<stringify> and
+C<tie>d C<FETCH> is enabled on the printed arguments. If C<frame
+& 16>, the return value from the subroutine is printed.
The length at which the argument list is truncated is governed by the
next option:
=item C<maxTraceLen>
-length at which the argument list is truncated when C<frame> option's
+Length to truncate the argument list when the C<frame> option's
bit 4 is set.
=back
=item C<compactDump>, C<veryCompact>
-Change style of array and hash dump. If C<compactDump>, short array
+Change the style of array and hash output. If C<compactDump>, short array
may be printed on one line.
=item C<globPrint>
=item C<quote>, C<HighBit>, C<undefPrint>
-Change style of string dump. Default value of C<quote> is C<auto>, one
-can enable either double-quotish dump, or single-quotish by setting it
-to C<"> or C<'>. By default, characters with high bit set are printed
-I<as is>.
+Change the style of string dump. The default value for C<quote>
+is C<auto>; one can enable double-quotish or single-quotish format
+by setting it to C<"> or C<'>, respectively. By default, characters
+with their high bit set are printed verbatim.
=item C<UsageOnly>
-I<very> rudimentally per-package memory usage dump. Calculates total
-size of strings in variables in the package.
+Rudimentary per-package memory usage dump. Calculates total
+size of strings found in variables in the package. This does not
+include lexicals in a module's file scope, or lost in closures.
=back
-During startup options are initialized from C<$ENV{PERLDB_OPTS}>.
-You can put additional initialization options C<TTY>, C<noTTY>,
+During startup, options are initialized from C<$ENV{PERLDB_OPTS}>.
+You may place the initialization options C<TTY>, C<noTTY>,
C<ReadLine>, and C<NonStop> there.
-Example rc file:
+If your rc file contains:
- &parse_options("NonStop=1 LineInfo=db.out AutoTrace");
+ parse_options("NonStop=1 LineInfo=db.out AutoTrace");
-The script will run without human intervention, putting trace information
-into the file I<db.out>. (If you interrupt it, you would better reset
-C<LineInfo> to something "interactive"!)
+then your script will run without human intervention, putting trace
+information into the file I<db.out>. (If you interrupt it, you'd
+better reset C<LineInfo> to F</dev/tty> if you expect to see anything.)
=over 12
=item C<noTTY>
-If set, goes in C<NonStop> mode, and would not connect to a TTY. If
-interrupt (or if control goes to debugger via explicit setting of
-$DB::signal or $DB::single from the Perl script), connects to a TTY
-specified by the C<TTY> option at startup, or to a TTY found at
-runtime using C<Term::Rendezvous> module of your choice.
+If set, the debugger goes into C<NonStop> mode and will not connect to a TTY. If
+interrupted (or if control goes to the debugger via explicit setting of
+$DB::signal or $DB::single from the Perl script), it connects to a TTY
+specified in the C<TTY> option at startup, or to a tty found at
+runtime using the C<Term::Rendezvous> module of your choice.
-This module should implement a method C<new> which returns an object
-with two methods: C<IN> and C<OUT>, returning two filehandles to use
-for debugging input and output correspondingly. Method C<new> may
-inspect an argument which is a value of C<$ENV{PERLDB_NOTTY}> at
-startup, or is C<"/tmp/perldbtty$$"> otherwise.
+This module should implement a method named C<new> that returns an object
+with two methods: C<IN> and C<OUT. These should return filehandles to use
+for debugging input and output correspondingly. The C<new> method should
+inspect an argument containing the value of C<$ENV{PERLDB_NOTTY}> at
+startup, or C<"/tmp/perldbtty$$"> otherwise. This file is not
+inspected for proper ownership, so security hazards are theoretically
+possible.
=item C<ReadLine>
-If false, readline support in debugger is disabled, so you can debug
-ReadLine applications.
+If false, readline support in the debugger is disabled in order
+to debug applications that themselves use ReadLine.
=item C<NonStop>
-If set, debugger goes into noninteractive mode until interrupted, or
+If set, the debugger goes into non-interactive mode until interrupted, or
programmatically by setting $DB::signal or $DB::single.
=back
Here's an example of using the C<$ENV{PERLDB_OPTS}> variable:
- $ PERLDB_OPTS="N f=2" perl -d myprogram
+ $ PERLDB_OPTS="NonStop frame=2" perl -d myprogram
-will run the script C<myprogram> without human intervention, printing
-out the call tree with entry and exit points. Note that C<N f=2> is
-equivalent to C<NonStop=1 frame=2>. Note also that at the moment when
-this documentation was written all the options to the debugger could
-be uniquely abbreviated by the first letter (with exception of
-C<Dump*> options).
+That will run the script B<myprogram> without human intervention,
+printing out the call tree with entry and exit points. Note that
+C<NonStop=1 frame=2> is equivalent to C<N f=2>, and that originally,
+options could be uniquely abbreviated by the first letter (modulo
+the C<Dump*> options). It is nevertheless recommended that you
+always spell them out in full for legibility and future compatibility.
-Other examples may include
+Other examples include
- $ PERLDB_OPTS="N f A L=listing" perl -d myprogram
+ $ PERLDB_OPTS="NonStop frame=2" perl -d myprogram
-- runs script noninteractively, printing info on each entry into a
-subroutine and each executed line into the file F<listing>. (If you
-interrupt it, you would better reset C<LineInfo> to something
+which runs script non-interactively, printing info on each entry
+into a subroutine and each executed line into the file named F<listing>.
+(If you interrupt it, you would better reset C<LineInfo> to something
"interactive"!)
+Other examples include (using standard shell syntax to show environment
+variable settings):
- $ env "PERLDB_OPTS=R=0 TTY=/dev/ttyc" perl -d myprogram
+ $ ( PERLDB_OPTS="NonStop frame=1 AutoTrace LineInfo=tperl.out"
+ perl -d myprogram )
-may be useful for debugging a program which uses C<Term::ReadLine>
-itself. Do not forget detach shell from the TTY in the window which
-corresponds to F</dev/ttyc>, say, by issuing a command like
+which may be useful for debugging a program that uses C<Term::ReadLine>
+itself. Do not forget to detach your shell from the TTY in the window that
+corresponds to F</dev/ttyXX>, say, by issuing a command like
$ sleep 1000000
-See L<"Debugger Internals"> below for more details.
-
-=item < [ command ]
-
-Set an action (Perl command) to happen before every debugger prompt.
-A multi-line command may be entered by backslashing the newlines. If
-C<command> is missing, resets the list of actions.
-
-=item << command
-
-Add an action (Perl command) to happen before every debugger prompt.
-A multi-line command may be entered by backslashing the newlines.
-
-=item > command
-
-Set an action (Perl command) to happen after the prompt when you've
-just given a command to return to executing the script. A multi-line
-command may be entered by backslashing the newlines. If C<command> is
-missing, resets the list of actions.
-
-=item >> command
-
-Adds an action (Perl command) to happen after the prompt when you've
-just given a command to return to executing the script. A multi-line
-command may be entered by backslashing the newlines.
-
-=item { [ command ]
-
-Set an action (debugger command) to happen before every debugger prompt.
-A multi-line command may be entered by backslashing the newlines. If
-C<command> is missing, resets the list of actions.
-
-=item {{ command
-
-Add an action (debugger command) to happen before every debugger prompt.
-A multi-line command may be entered by backslashing the newlines.
-
-=item ! number
-
-Redo a previous command (default previous command).
-
-=item ! -number
-
-Redo number'th-to-last command.
-
-=item ! pattern
-
-Redo last command that started with pattern.
-See C<O recallCommand>, too.
-
-=item !! cmd
-
-Run cmd in a subprocess (reads from DB::IN, writes to DB::OUT)
-See C<O shellBang> too.
-
-=item H -number
-
-Display last n commands. Only commands longer than one character are
-listed. If number is omitted, lists them all.
-
-=item q or ^D
-
-Quit. ("quit" doesn't work for this.) This is the only supported way
-to exit the debugger, though typing C<exit> twice may do it too.
-
-Set an C<O>ption C<inhibit_exit> to 0 if you want to be able to I<step
-off> the end the script. You may also need to set $finished to 0 at
-some moment if you want to step through global destruction.
-
-=item R
-
-Restart the debugger by B<exec>ing a new session. It tries to maintain
-your history across this, but internal settings and command line options
-may be lost.
-
-Currently the following setting are preserved: history, breakpoints,
-actions, debugger C<O>ptions, and the following command line
-options: B<-w>, B<-I>, and B<-e>.
-
-=item |dbcmd
-
-Run debugger command, piping DB::OUT to current pager.
-
-=item ||dbcmd
-
-Same as C<|dbcmd> but DB::OUT is temporarily B<select>ed as well.
-Often used with commands that would otherwise produce long
-output, such as
-
- |V main
-
-=item = [alias value]
-
-Define a command alias, like
-
- = quit q
-
-or list current aliases.
-
-=item command
-
-Execute command as a Perl statement. A missing semicolon will be
-supplied.
-
-=item m expr
-
-The expression is evaluated, and the methods which may be applied to
-the result are listed.
-
-=item m package
-
-The methods which may be applied to objects in the C<package> are listed.
-
-=back
+See L<perldebguts/"Debugger Internals"> for details.
=head2 Debugger input/output
DB<<17>>
-where that number is the command number, which you'd use to access with
-the builtin B<csh>-like history mechanism, e.g., C<!17> would repeat
-command number 17. The number of angle brackets indicates the depth of
-the debugger. You could get more than one set of brackets, for example, if
-you'd already at a breakpoint and then printed out the result of a
-function call that itself also has a breakpoint, or you step into an
-expression via C<s/n/t expression> command.
+where that number is the command number, and which you'd use to
+access with the built-in B<csh>-like history mechanism. For example,
+C<!17> would repeat command number 17. The depth of the angle
+brackets indicates the nesting depth of the debugger. You could
+get more than one set of brackets, for example, if you'd already
+at a breakpoint and then printed the result of a function call that
+itself has a breakpoint, or you step into an expression via C<s/n/t
+expression> command.
=item Multiline commands
If you want to enter a multi-line command, such as a subroutine
-definition with several statements, or a format, you may escape the
-newline that would normally end the debugger command with a backslash.
+definition with several statements or a format, escape the newline
+that would normally end the debugger command with a backslash.
Here's an example:
DB<1> for (1..4) { \
@ = Ambulation::legs(1, 2, 3, 4) called from file `camel_flea' line 7
$ = main::pests('bactrian', 4) called from file `camel_flea' line 4
-The left-hand character up there tells whether the function was called
-in a scalar or list context (we bet you can tell which is which). What
-that says is that you were in the function C<main::infested> when you ran
-the stack dump, and that it was called in a scalar context from line 10
-of the file I<Ambulation.pm>, but without any arguments at all, meaning
-it was called as C<&infested>. The next stack frame shows that the
-function C<Ambulation::legs> was called in a list context from the
-I<camel_flea> file with four arguments. The last stack frame shows that
-C<main::pests> was called in a scalar context, also from I<camel_flea>,
-but from line 4.
+The left-hand character up there indicates the context in which the
+function was called, with C<$> and C<@> meaning scalar or list
+contexts respectively, and C<.> meaning void context (which is
+actually a sort of scalar context). The display above says
+that you were in the function C<main::infested> when you ran the
+stack dump, and that it was called in scalar context from line
+10 of the file I<Ambulation.pm>, but without any arguments at all,
+meaning it was called as C<&infested>. The next stack frame shows
+that the function C<Ambulation::legs> was called in list context
+from the I<camel_flea> file with four arguments. The last stack
+frame shows that C<main::pests> was called in scalar context,
+also from I<camel_flea>, but from line 4.
-Note that if you execute C<T> command from inside an active C<use>
-statement, the backtrace will contain both C<require>
-frame and an C<eval>) frame.
+If you execute the C<T> command from inside an active C<use>
+statement, the backtrace will contain both a C<require> frame and
+an C<eval>) frame.
-=item Listing
+=item Line Listing Format
-Listing given via different flavors of C<l> command looks like this:
+This shows the sorts of output the C<l> command can produce:
DB<<13>> l
101: @i{@i} = ();
109:a if ($extra-- > 0) {
110: %isa = ($pack,1);
-Note that the breakable lines are marked with C<:>, lines with
-breakpoints are marked by C<b>, with actions by C<a>, and the
-next executed line is marked by C<< ==> >>.
+Breakable lines are marked with C<:>. Lines with breakpoints are
+marked by C<b> and those with actions by C<a>. The line that's
+about to be executed is marked by C<< ==> >>.
=item Frame listing
-When C<frame> option is set, debugger would print entered (and
-optionally exited) subroutines in different styles.
-
-What follows is the start of the listing of
-
- env "PERLDB_OPTS=f=n N" perl -d -V
-
-for different values of C<n>:
-
-=over 4
-
-=item 1
-
- entering main::BEGIN
- entering Config::BEGIN
- Package lib/Exporter.pm.
- Package lib/Carp.pm.
- Package lib/Config.pm.
- entering Config::TIEHASH
- entering Exporter::import
- entering Exporter::export
- entering Config::myconfig
- entering Config::FETCH
- entering Config::FETCH
- entering Config::FETCH
- entering Config::FETCH
-
-=item 2
-
- entering main::BEGIN
- entering Config::BEGIN
- Package lib/Exporter.pm.
- Package lib/Carp.pm.
- exited Config::BEGIN
- Package lib/Config.pm.
- entering Config::TIEHASH
- exited Config::TIEHASH
- entering Exporter::import
- entering Exporter::export
- exited Exporter::export
- exited Exporter::import
- exited main::BEGIN
- entering Config::myconfig
- entering Config::FETCH
- exited Config::FETCH
- entering Config::FETCH
- exited Config::FETCH
- entering Config::FETCH
-
-=item 4
-
- in $=main::BEGIN() from /dev/nul:0
- in $=Config::BEGIN() from lib/Config.pm:2
- Package lib/Exporter.pm.
- Package lib/Carp.pm.
- Package lib/Config.pm.
- in $=Config::TIEHASH('Config') from lib/Config.pm:644
- in $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/nul:0
- in $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from li
- in @=Config::myconfig() from /dev/nul:0
- in $=Config::FETCH(ref(Config), 'package') from lib/Config.pm:574
- in $=Config::FETCH(ref(Config), 'baserev') from lib/Config.pm:574
- in $=Config::FETCH(ref(Config), 'PERL_VERSION') from lib/Config.pm:574
- in $=Config::FETCH(ref(Config), 'PERL_SUBVERSION') from lib/Config.pm:574
- in $=Config::FETCH(ref(Config), 'osname') from lib/Config.pm:574
- in $=Config::FETCH(ref(Config), 'osvers') from lib/Config.pm:574
-
-=item 6
-
- in $=main::BEGIN() from /dev/nul:0
- in $=Config::BEGIN() from lib/Config.pm:2
- Package lib/Exporter.pm.
- Package lib/Carp.pm.
- out $=Config::BEGIN() from lib/Config.pm:0
- Package lib/Config.pm.
- in $=Config::TIEHASH('Config') from lib/Config.pm:644
- out $=Config::TIEHASH('Config') from lib/Config.pm:644
- in $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/nul:0
- in $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/
- out $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/
- out $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/nul:0
- out $=main::BEGIN() from /dev/nul:0
- in @=Config::myconfig() from /dev/nul:0
- in $=Config::FETCH(ref(Config), 'package') from lib/Config.pm:574
- out $=Config::FETCH(ref(Config), 'package') from lib/Config.pm:574
- in $=Config::FETCH(ref(Config), 'baserev') from lib/Config.pm:574
- out $=Config::FETCH(ref(Config), 'baserev') from lib/Config.pm:574
- in $=Config::FETCH(ref(Config), 'PERL_VERSION') from lib/Config.pm:574
- out $=Config::FETCH(ref(Config), 'PERL_VERSION') from lib/Config.pm:574
- in $=Config::FETCH(ref(Config), 'PERL_SUBVERSION') from lib/Config.pm:574
-
-=item 14
-
- in $=main::BEGIN() from /dev/nul:0
- in $=Config::BEGIN() from lib/Config.pm:2
- Package lib/Exporter.pm.
- Package lib/Carp.pm.
- out $=Config::BEGIN() from lib/Config.pm:0
- Package lib/Config.pm.
- in $=Config::TIEHASH('Config') from lib/Config.pm:644
- out $=Config::TIEHASH('Config') from lib/Config.pm:644
- in $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/nul:0
- in $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/E
- out $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/E
- out $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/nul:0
- out $=main::BEGIN() from /dev/nul:0
- in @=Config::myconfig() from /dev/nul:0
- in $=Config::FETCH('Config=HASH(0x1aa444)', 'package') from lib/Config.pm:574
- out $=Config::FETCH('Config=HASH(0x1aa444)', 'package') from lib/Config.pm:574
- in $=Config::FETCH('Config=HASH(0x1aa444)', 'baserev') from lib/Config.pm:574
- out $=Config::FETCH('Config=HASH(0x1aa444)', 'baserev') from lib/Config.pm:574
-
-=item 30
-
- in $=CODE(0x15eca4)() from /dev/null:0
- in $=CODE(0x182528)() from lib/Config.pm:2
- Package lib/Exporter.pm.
- out $=CODE(0x182528)() from lib/Config.pm:0
- scalar context return from CODE(0x182528): undef
- Package lib/Config.pm.
- in $=Config::TIEHASH('Config') from lib/Config.pm:628
- out $=Config::TIEHASH('Config') from lib/Config.pm:628
- scalar context return from Config::TIEHASH: empty hash
- in $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0
- in $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/Exporter.pm:171
- out $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/Exporter.pm:171
- scalar context return from Exporter::export: ''
- out $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0
- scalar context return from Exporter::import: ''
-
-
-=back
-
-In all the cases indentation of lines shows the call tree, if bit 2 of
-C<frame> is set, then a line is printed on exit from a subroutine as
-well, if bit 4 is set, then the arguments are printed as well as the
-caller info, if bit 8 is set, the arguments are printed even if they
-are tied or references, if bit 16 is set, the return value is printed
-as well.
-
-When a package is compiled, a line like this
-
- Package lib/Carp.pm.
-
-is printed with proper indentation.
+When the C<frame> option is set, the debugger would print entered (and
+optionally exited) subroutines in different styles. See L<perldebguts>
+for incredibly long examples of these.
=back
=head2 Debugging compile-time statements
-If you have any compile-time executable statements (code within a BEGIN
-block or a C<use> statement), these will C<NOT> be stopped by debugger,
-although C<require>s will (and compile-time statements can be traced
-with C<AutoTrace> option set in C<PERLDB_OPTS>). From your own Perl
-code, however, you can
+If you have compile-time executable statements (such as code within
+BEGIN and CHECK blocks or C<use> statements), these will I<not> be
+stopped by debugger, although C<require>s and INIT blocks will, and
+compile-time statements can be traced with C<AutoTrace> option set
+in C<PERLDB_OPTS>). From your own Perl code, however, you can
transfer control back to the debugger using the following statement,
which is harmless if the debugger is not running:
$DB::single = 1;
-If you set C<$DB::single> to the value 2, it's equivalent to having
+If you set C<$DB::single> to 2, it's equivalent to having
just typed the C<n> command, whereas a value of 1 means the C<s>
command. The C<$DB::trace> variable should be set to 1 to simulate
having typed the C<t> command.
-Another way to debug compile-time code is to start debugger, set a
-breakpoint on I<load> of some module thusly
+Another way to debug compile-time code is to start the debugger, set a
+breakpoint on the I<load> of some module:
DB<7> b load f:/perllib/lib/Carp.pm
Will stop on load of `f:/perllib/lib/Carp.pm'.
-and restart debugger by C<R> command (if possible). One can use C<b
+and then restart the debugger using the C<R> command (if possible). One can use C<b
compile subname> for the same purpose.
=head2 Debugger Customization
-Most probably you do not want to modify the debugger, it contains enough
-hooks to satisfy most needs. You may change the behaviour of debugger
-from the debugger itself, using C<O>ptions, from the command line via
-C<PERLDB_OPTS> environment variable, and from I<customization files>.
+The debugger probably contains enough configuration hooks that you
+won't ever have to modify it yourself. You may change the behaviour
+of debugger from within the debugger using its C<O> command, from
+the command line via the C<PERLDB_OPTS> environment variable, and
+from customization files.
-You can do some customization by setting up a F<.perldb> file which
+You can do some customization by setting up a F<.perldb> file, which
contains initialization code. For instance, you could make aliases
like these (the last one is one people expect to be there):
$DB::alias{'len'} = 's/^len(.*)/p length($1)/';
$DB::alias{'stop'} = 's/^stop (at|in)/b/';
$DB::alias{'ps'} = 's/^ps\b/p scalar /';
- $DB::alias{'quit'} = 's/^quit(\s*)/exit\$/';
+ $DB::alias{'quit'} = 's/^quit(\s*)/exit/';
-One changes options from F<.perldb> file via calls like this one;
+You can change options from F<.perldb> by using calls like this one;
parse_options("NonStop=1 LineInfo=db.out AutoTrace=1 frame=2");
-(the code is executed in the package C<DB>). Note that F<.perldb> is
+The code is executed in the package C<DB>. Note that F<.perldb> is
processed before processing C<PERLDB_OPTS>. If F<.perldb> defines the
-subroutine C<afterinit>, it is called after all the debugger
+subroutine C<afterinit>, that function is called after debugger
initialization ends. F<.perldb> may be contained in the current
-directory, or in the C<LOGDIR>/C<HOME> directory.
+directory, or in the home directory. Because this file is sourced
+in by Perl and may contain arbitrary commands, for security reasons,
+it must be owned by the superuser or the current user, and writable
+by no one but its owner.
-If you want to modify the debugger, copy F<perl5db.pl> from the Perl
-library to another name and modify it as necessary. You'll also want
-to set your C<PERL5DB> environment variable to say something like this:
+If you want to modify the debugger, copy F<perl5db.pl> from the
+Perl library to another name and hack it to your heart's content.
+You'll then want to set your C<PERL5DB> environment variable to say
+something like this:
BEGIN { require "myperl5db.pl" }
-As the last resort, one can use C<PERL5DB> to customize debugger by
-directly setting internal variables or calling debugger functions.
+As a last resort, you could also use C<PERL5DB> to customize the debugger
+by directly setting internal variables or calling debugger functions.
+
+Note that any variables and functions that are not documented in
+this document (or in L<perldebguts>) are considered for internal
+use only, and as such are subject to change without notice.
=head2 Readline Support
-As shipped, the only command line history supplied is a simplistic one
+As shipped, the only command-line history supplied is a simplistic one
that checks for leading exclamation points. However, if you install
the Term::ReadKey and Term::ReadLine modules from CPAN, you will
have full editing capabilities much like GNU I<readline>(3) provides.
Look for these in the F<modules/by-module/Term> directory on CPAN.
+These do not support normal B<vi> command-line editing, however.
-A rudimentary command line completion is also available.
+A rudimentary command-line completion is also available.
Unfortunately, the names of lexical variables are not available for
completion.
=head2 Editor Support for Debugging
-If you have GNU B<emacs> installed on your system, it can interact with
-the Perl debugger to provide an integrated software development
-environment reminiscent of its interactions with C debuggers.
-
-Perl is also delivered with a start file for making B<emacs> act like a
-syntax-directed editor that understands (some of) Perl's syntax. Look in
-the I<emacs> directory of the Perl source distribution.
-
-(Historically, a similar setup for interacting with B<vi> and the
-X11 window system had also been available, but at the time of this
-writing, no debugger support for B<vi> currently exists.)
-
-=head2 The Perl Profiler
-
-If you wish to supply an alternative debugger for Perl to run, just
-invoke your script with a colon and a package argument given to the B<-d>
-flag. One of the most popular alternative debuggers for Perl is
-B<DProf>, the Perl profiler. As of this writing, B<DProf> is not
-included with the standard Perl distribution, but it is expected to
-be included soon, for certain values of "soon".
-
-Meanwhile, you can fetch the Devel::Dprof module from CPAN. Assuming
-it's properly installed on your system, to profile your Perl program in
-the file F<mycode.pl>, just type:
-
- perl -d:DProf mycode.pl
-
-When the script terminates the profiler will dump the profile information
-to a file called F<tmon.out>. A tool like B<dprofpp> (also supplied with
-the Devel::DProf package) can be used to interpret the information which is
-in that profile.
+If you have the FSF's version of B<emacs> installed on your system,
+it can interact with the Perl debugger to provide an integrated
+software development environment reminiscent of its interactions
+with C debuggers.
-=head2 Debugger support in perl
+Perl comes with a start file for making B<emacs> act like a
+syntax-directed editor that understands (some of) Perl's syntax.
+Look in the I<emacs> directory of the Perl source distribution.
-When you call the B<caller> function (see L<perlfunc/caller>) from the
-package DB, Perl sets the array @DB::args to contain the arguments the
-corresponding stack frame was called with.
+A similar setup by Tom Christiansen for interacting with any
+vendor-shipped B<vi> and the X11 window system is also available.
+This works similarly to the integrated multiwindow support that
+B<emacs> provides, where the debugger drives the editor. At the
+time of this writing, however, that tool's eventual location in the
+Perl distribution was uncertain.
-If perl is run with B<-d> option, the following additional features
-are enabled (cf. L<perlvar/$^P>):
-
-=over
-
-=item *
-
-Perl inserts the contents of C<$ENV{PERL5DB}> (or C<BEGIN {require
-'perl5db.pl'}> if not present) before the first line of the
-application.
-
-=item *
-
-The array C<@{"_<$filename"}> is the line-by-line contents of
-$filename for all the compiled files. Same for C<eval>ed strings which
-contain subroutines, or which are currently executed. The $filename
-for C<eval>ed strings looks like C<(eval 34)>.
-
-=item *
-
-The hash C<%{"_<$filename"}> contains breakpoints and action (it is
-keyed by line number), and individual entries are settable (as opposed
-to the whole hash). Only true/false is important to Perl, though the
-values used by F<perl5db.pl> have the form
-C<"$break_condition\0$action">. Values are magical in numeric context:
-they are zeros if the line is not breakable.
-
-Same for evaluated strings which contain subroutines, or which are
-currently executed. The $filename for C<eval>ed strings looks like
-C<(eval 34)>.
-
-=item *
-
-The scalar C<${"_<$filename"}> contains C<"_<$filename">. Same for
-evaluated strings which contain subroutines, or which are currently
-executed. The $filename for C<eval>ed strings looks like C<(eval
-34)>.
-
-=item *
-
-After each C<require>d file is compiled, but before it is executed,
-C<DB::postponed(*{"_<$filename"})> is called (if subroutine
-C<DB::postponed> exists). Here the $filename is the expanded name of
-the C<require>d file (as found in values of %INC).
-
-=item *
-
-After each subroutine C<subname> is compiled existence of
-C<$DB::postponed{subname}> is checked. If this key exists,
-C<DB::postponed(subname)> is called (if subroutine C<DB::postponed>
-exists).
-
-=item *
-
-A hash C<%DB::sub> is maintained, with keys being subroutine names,
-values having the form C<filename:startline-endline>. C<filename> has
-the form C<(eval 31)> for subroutines defined inside C<eval>s.
-
-=item *
-
-When execution of the application reaches a place that can have
-a breakpoint, a call to C<DB::DB()> is performed if any one of
-variables $DB::trace, $DB::single, or $DB::signal is true. (Note that
-these variables are not C<local>izable.) This feature is disabled when
-the control is inside C<DB::DB()> or functions called from it (unless
-C<$^D & (1<<30)>).
-
-=item *
-
-When execution of the application reaches a subroutine call, a call
-to C<&DB::sub>(I<args>) is performed instead, with C<$DB::sub> being
-the name of the called subroutine. (Unless the subroutine is compiled
-in the package C<DB>.)
-
-=back
+Users of B<vi> should also look into B<vim> and B<gvim>, the mousey
+and windy version, for coloring of Perl keywords.
-Note that if C<&DB::sub> needs some external data to be setup for it
-to work, no subroutine call is possible until this is done. For the
-standard debugger C<$DB::deep> (how many levels of recursion deep into
-the debugger you can go before a mandatory break) gives an example of
-such a dependency.
+Note that only perl can truly parse Perl, so all such CASE tools
+fall somewhat short of the mark, especially if you don't program
+your Perl as a C programmer might.
-The minimal working debugger consists of one line
-
- sub DB::DB {}
-
-which is quite handy as contents of C<PERL5DB> environment
-variable:
-
- env "PERL5DB=sub DB::DB {}" perl -d your-script
-
-Another (a little bit more useful) minimal debugger can be created
-with the only line being
-
- sub DB::DB {print ++$i; scalar <STDIN>}
-
-This debugger would print the sequential number of encountered
-statement, and would wait for your C<CR> to continue.
-
-The following debugger is quite functional:
-
- {
- package DB;
- sub DB {}
- sub sub {print ++$i, " $sub\n"; &$sub}
- }
+=head2 The Perl Profiler
-It prints the sequential number of subroutine call and the name of the
-called subroutine. Note that C<&DB::sub> should be compiled into the
-package C<DB>.
+If you wish to supply an alternative debugger for Perl to run, just
+invoke your script with a colon and a package argument given to the
+B<-d> flag. The most popular alternative debuggers for Perl is the
+Perl profiler. Devel::DProf is now included with the standard Perl
+distribution. To profile your Perl program in the file F<mycode.pl>,
+just type:
-=head2 Debugger Internals
+ $ perl -d:DProf mycode.pl
-At the start, the debugger reads your rc file (F<./.perldb> or
-F<~/.perldb> under Unix), which can set important options. This file may
-define a subroutine C<&afterinit> to be executed after the debugger is
-initialized.
+When the script terminates the profiler will dump the profile
+information to a file called F<tmon.out>. A tool like B<dprofpp>,
+also supplied with the standard Perl distribution, can be used to
+interpret the information in that profile.
-After the rc file is read, the debugger reads environment variable
-PERLDB_OPTS and parses it as a rest of C<O ...> line in debugger prompt.
+=head1 Debugging regular expressions
-It also maintains magical internal variables, such as C<@DB::dbline>,
-C<%DB::dbline>, which are aliases for C<@{"::_<current_file"}>
-C<%{"::_<current_file"}>. Here C<current_file> is the currently
-selected (with the debugger's C<f> command, or by flow of execution)
-file.
+C<use re 'debug'> enables you to see the gory details of how the
+Perl regular expression engine works. In order to understand this
+typically voluminous output, one must not only have some idea about
+about how regular expression matching works in general, but also
+know how Perl's regular expressions are internally compiled into
+an automaton. These matters are explored in some detail in
+L<perldebguts/"Debugging regular expressions">.
-Some functions are provided to simplify customization. See L<"Debugger
-Customization"> for description of C<DB::parse_options(string)>. The
-function C<DB::dump_trace(skip[, count])> skips the specified number
-of frames, and returns a list containing info about the caller
-frames (all if C<count> is missing). Each entry is a hash with keys
-C<context> (C<$> or C<@>), C<sub> (subroutine name, or info about
-eval), C<args> (C<undef> or a reference to an array), C<file>, and
-C<line>.
+=head1 Debugging memory usage
-The function C<DB::print_trace(FH, skip[, count[, short]])> prints
-formatted info about caller frames. The last two functions may be
-convenient as arguments to C<< < >>, C<< << >> commands.
+Perl contains internal support for reporting its own memory usage,
+but this is a fairly advanced concept that requires some understanding
+of how memory allocation works.
+See L<perldebguts/"Debugging Perl memory usage"> for the details.
-=head2 Other resources
+=head1 SEE ALSO
You did try the B<-w> switch, didn't you?
-=head2 BUGS
+L<perldebguts>,
+L<re>,
+L<DB>,
+L<Devel::Dprof>,
+L<dprofpp>,
+L<Dumpvalue>,
+and
+L<perlrun>.
-You cannot get the stack frame information or otherwise debug functions
-that were not compiled by Perl, such as C or C++ extensions.
+=head1 BUGS
+
+You cannot get stack frame information or in any fashion debug functions
+that were not compiled by Perl, such as those from C or C++ extensions.
If you alter your @_ arguments in a subroutine (such as with B<shift>
or B<pop>, the stack backtrace will not show the original values.
-
-=head1 Debugging Perl memory usage
-
-Perl is I<very> frivolous with memory. There is a saying that to
-estimate memory usage of Perl, assume a reasonable algorithm of
-allocation, and multiply your estimates by 10. This is not absolutely
-true, but may give you a good grasp of what happens.
-
-Say, an integer cannot take less than 20 bytes of memory, a float
-cannot take less than 24 bytes, a string cannot take less than 32
-bytes (all these examples assume 32-bit architectures, the result are
-much worse on 64-bit architectures). If a variable is accessed in two
-of three different ways (which require an integer, a float, or a
-string), the memory footprint may increase by another 20 bytes. A
-sloppy malloc() implementation will make these numbers yet more.
-
-On the opposite end of the scale, a declaration like
-
- sub foo;
-
-may take (on some versions of perl) up to 500 bytes of memory.
-
-Off-the-cuff anecdotal estimates of a code bloat give a factor around
-8. This means that the compiled form of reasonable (commented
-indented etc.) code will take approximately 8 times more than the
-disk space the code takes.
-
-There are two Perl-specific ways to analyze the memory usage:
-$ENV{PERL_DEBUG_MSTATS} and B<-DL> switch. First one is available
-only if perl is compiled with Perl's malloc(), the second one only if
-Perl compiled with C<-DDEBUGGING> (as with giving C<-D optimise=-g>
-option to F<Configure>).
-
-=head2 Using C<$ENV{PERL_DEBUG_MSTATS}>
-
-If your perl is using Perl's malloc(), and compiled with correct
-switches (this is the default), then it will print memory usage
-statistics after compiling your code (if C<$ENV{PERL_DEBUG_MSTATS}> >
-1), and before termination of the script (if
-C<$ENV{PERL_DEBUG_MSTATS}> >= 1). The report format is similar to one
-in the following example:
-
- env PERL_DEBUG_MSTATS=2 perl -e "require Carp"
- Memory allocation statistics after compilation: (buckets 4(4)..8188(8192)
- 14216 free: 130 117 28 7 9 0 2 2 1 0 0
- 437 61 36 0 5
- 60924 used: 125 137 161 55 7 8 6 16 2 0 1
- 74 109 304 84 20
- Total sbrk(): 77824/21:119. Odd ends: pad+heads+chain+tail: 0+636+0+2048.
- Memory allocation statistics after execution: (buckets 4(4)..8188(8192)
- 30888 free: 245 78 85 13 6 2 1 3 2 0 1
- 315 162 39 42 11
- 175816 used: 265 176 1112 111 26 22 11 27 2 1 1
- 196 178 1066 798 39
- Total sbrk(): 215040/47:145. Odd ends: pad+heads+chain+tail: 0+2192+0+6144.
-
-It is possible to ask for such a statistic at arbitrary moment by
-using Devel::Peek::mstats() (module Devel::Peek is available on CPAN).
-
-Here is the explanation of different parts of the format:
-
-=over
-
-=item C<buckets SMALLEST(APPROX)..GREATEST(APPROX)>
-
-Perl's malloc() uses bucketed allocations. Every request is rounded
-up to the closest bucket size available, and a bucket of these size is
-taken from the pool of the buckets of this size.
-
-The above line describes limits of buckets currently in use. Each
-bucket has two sizes: memory footprint, and the maximal size of user
-data which may be put into this bucket. Say, in the above example the
-smallest bucket is both sizes 4. The biggest bucket has usable size
-8188, and the memory footprint 8192.
-
-With debugging Perl some buckets may have negative usable size. This
-means that these buckets cannot (and will not) be used. For greater
-buckets the memory footprint may be one page greater than a power of
-2. In such a case the corresponding power of two is printed instead
-in the C<APPROX> field above.
-
-=item Free/Used
-
-The following 1 or 2 rows of numbers correspond to the number of
-buckets of each size between C<SMALLEST> and C<GREATEST>. In the
-first row the sizes (memory footprints) of buckets are powers of two
-(or possibly one page greater). In the second row (if present) the
-memory footprints of the buckets are between memory footprints of two
-buckets "above".
-
-Say, with the above example the memory footprints are (with current
-algorithm)
-
- free: 8 16 32 64 128 256 512 1024 2048 4096 8192
- 4 12 24 48 80
-
-With non-C<DEBUGGING> perl the buckets starting from C<128>-long ones
-have 4-byte overhead, thus 8192-long bucket may take up to
-8188-byte-long allocations.
-
-=item C<Total sbrk(): SBRKed/SBRKs:CONTINUOUS>
-
-The first two fields give the total amount of memory perl sbrk()ed,
-and number of sbrk()s used. The third number is what perl thinks
-about continuity of returned chunks. As far as this number is
-positive, malloc() will assume that it is probable that sbrk() will
-provide continuous memory.
-
-The amounts sbrk()ed by external libraries is not counted.
-
-=item C<pad: 0>
-
-The amount of sbrk()ed memory needed to keep buckets aligned.
-
-=item C<heads: 2192>
-
-While memory overhead of bigger buckets is kept inside the bucket, for
-smaller buckets it is kept in separate areas. This field gives the
-total size of these areas.
-
-=item C<chain: 0>
-
-malloc() may want to subdivide a bigger bucket into smaller buckets.
-If only a part of the deceased-bucket is left non-subdivided, the rest
-is kept as an element of a linked list. This field gives the total
-size of these chunks.
-
-=item C<tail: 6144>
-
-To minimize amount of sbrk()s malloc() asks for more memory. This
-field gives the size of the yet-unused part, which is sbrk()ed, but
-never touched.
-
-=back
-
-=head2 Example of using B<-DL> switch
-
-Below we show how to analyse memory usage by
-
- do 'lib/auto/POSIX/autosplit.ix';
-
-The file in question contains a header and 146 lines similar to
-
- sub getcwd ;
-
-B<Note:> I<the discussion below supposes 32-bit architecture. In the
-newer versions of perl the memory usage of the constructs discussed
-here is much improved, but the story discussed below is a real-life
-story. This story is very terse, and assumes more than cursory
-knowledge of Perl internals.>
-
-Here is the itemized list of Perl allocations performed during parsing
-of this file:
-
- !!! "after" at test.pl line 3.
- Id subtot 4 8 12 16 20 24 28 32 36 40 48 56 64 72 80 80+
- 0 02 13752 . . . . 294 . . . . . . . . . . 4
- 0 54 5545 . . 8 124 16 . . . 1 1 . . . . . 3
- 5 05 32 . . . . . . . 1 . . . . . . . .
- 6 02 7152 . . . . . . . . . . 149 . . . . .
- 7 02 3600 . . . . . 150 . . . . . . . . . .
- 7 03 64 . -1 . 1 . . 2 . . . . . . . . .
- 7 04 7056 . . . . . . . . . . . . . . . 7
- 7 17 38404 . . . . . . . 1 . . 442 149 . . 147 .
- 9 03 2078 17 249 32 . . . . 2 . . . . . . . .
-
-
-To see this list insert two C<warn('!...')> statements around the call:
-
- warn('!');
- do 'lib/auto/POSIX/autosplit.ix';
- warn('!!! "after"');
-
-and run it with B<-DL> option. The first warn() will print memory
-allocation info before the parsing of the file, and will memorize the
-statistics at this point (we ignore what it prints). The second warn()
-will print increments w.r.t. this memorized statistics. This is the
-above printout.
-
-Different I<Id>s on the left correspond to different subsystems of
-perl interpreter, they are just first argument given to perl memory
-allocation API New(). To find what C<9 03> means C<grep> the perl
-source for C<903>. You will see that it is F<util.c>, function
-savepvn(). This function is used to store a copy of existing chunk of
-memory. Using C debugger, one can see that it is called either
-directly from gv_init(), or via sv_magic(), and gv_init() is called
-from gv_fetchpv() - which is called from newSUB().
-
-B<Note:> to reach this place in debugger and skip all the calls to
-savepvn during the compilation of the main script, set a C breakpoint
-in Perl_warn(), C<continue> this point is reached, I<then> set
-breakpoint in Perl_savepvn(). Note that you may need to skip a
-handful of Perl_savepvn() which do not correspond to mass production
-of CVs (there are more C<903> allocations than 146 similar lines of
-F<lib/auto/POSIX/autosplit.ix>). Note also that C<Perl_> prefixes are
-added by macroization code in perl header files to avoid conflicts
-with external libraries.
-
-Anyway, we see that C<903> ids correspond to creation of globs, twice
-per glob - for glob name, and glob stringification magic.
-
-Here are explanations for other I<Id>s above:
-
-=over
-
-=item C<717>
-
-is for creation of bigger C<XPV*> structures. In the above case it
-creates 3 C<AV> per subroutine, one for a list of lexical variable
-names, one for a scratchpad (which contains lexical variables and
-C<targets>), and one for the array of scratchpads needed for
-recursion.
-
-It also creates a C<GV> and a C<CV> per subroutine (all called from
-start_subparse()).
-
-=item C<002>
-
-Creates C array corresponding to the C<AV> of scratchpads, and the
-scratchpad itself (the first fake entry of this scratchpad is created
-though the subroutine itself is not defined yet).
-
-It also creates C arrays to keep data for the stash (this is one HV,
-but it grows, thus there are 4 big allocations: the big chunks are not
-freed, but are kept as additional arenas for C<SV> allocations).
-
-=item C<054>
-
-creates a C<HEK> for the name of the glob for the subroutine (this
-name is a key in a I<stash>).
-
-Big allocations with this I<Id> correspond to allocations of new
-arenas to keep C<HE>.
-
-=item C<602>
-
-creates a C<GP> for the glob for the subroutine.
-
-=item C<702>
-
-creates the C<MAGIC> for the glob for the subroutine.
-
-=item C<704>
-
-creates I<arenas> which keep SVs.
-
-=back
-
-=head2 B<-DL> details
-
-If Perl is run with B<-DL> option, then warn()s which start with `!'
-behave specially. They print a list of I<categories> of memory
-allocations, and statistics of allocations of different sizes for
-these categories.
-
-If warn() string starts with
-
-=over
-
-=item C<!!!>
-
-print changed categories only, print the differences in counts of allocations;
-
-=item C<!!>
-
-print grown categories only; print the absolute values of counts, and totals;
-
-=item C<!>
-
-print nonempty categories, print the absolute values of counts and totals.
-
-=back
-
-=head2 Limitations of B<-DL> statistic
-
-If an extension or an external library does not use Perl API to
-allocate memory, these allocations are not counted.
-
-=head1 Debugging regular expressions
-
-There are two ways to enable debugging output for regular expressions.
-
-If your perl is compiled with C<-DDEBUGGING>, you may use the
-B<-Dr> flag on the command line.
-
-Otherwise, one can C<use re 'debug'>, which has effects both at
-compile time, and at run time (and is I<not> lexically scoped).
-
-=head2 Compile-time output
-
-The debugging output for the compile time looks like this:
-
- compiling RE `[bc]d(ef*g)+h[ij]k$'
- size 43 first at 1
- 1: ANYOF(11)
- 11: EXACT <d>(13)
- 13: CURLYX {1,32767}(27)
- 15: OPEN1(17)
- 17: EXACT <e>(19)
- 19: STAR(22)
- 20: EXACT <f>(0)
- 22: EXACT <g>(24)
- 24: CLOSE1(26)
- 26: WHILEM(0)
- 27: NOTHING(28)
- 28: EXACT <h>(30)
- 30: ANYOF(40)
- 40: EXACT <k>(42)
- 42: EOL(43)
- 43: END(0)
- anchored `de' at 1 floating `gh' at 3..2147483647 (checking floating)
- stclass `ANYOF' minlen 7
-
-The first line shows the pre-compiled form of the regexp, and the
-second shows the size of the compiled form (in arbitrary units,
-usually 4-byte words) and the label I<id> of the first node which
-does a match.
-
-The last line (split into two lines in the above) contains the optimizer
-info. In the example shown, the optimizer found that the match
-should contain a substring C<de> at the offset 1, and substring C<gh>
-at some offset between 3 and infinity. Moreover, when checking for
-these substrings (to abandon impossible matches quickly) it will check
-for the substring C<gh> before checking for the substring C<de>. The
-optimizer may also use the knowledge that the match starts (at the
-C<first> I<id>) with a character class, and the match cannot be
-shorter than 7 chars.
-
-The fields of interest which may appear in the last line are
-
-=over
-
-=item C<anchored> I<STRING> C<at> I<POS>
-
-=item C<floating> I<STRING> C<at> I<POS1..POS2>
-
-see above;
-
-=item C<matching floating/anchored>
-
-which substring to check first;
-
-=item C<minlen>
-
-the minimal length of the match;
-
-=item C<stclass> I<TYPE>
-
-The type of the first matching node.
-
-=item C<noscan>
-
-which advises to not scan for the found substrings;
-
-=item C<isall>
-
-which says that the optimizer info is in fact all that the regular
-expression contains (thus one does not need to enter the RE engine at
-all);
-
-=item C<GPOS>
-
-if the pattern contains C<\G>;
-
-=item C<plus>
-
-if the pattern starts with a repeated char (as in C<x+y>);
-
-=item C<implicit>
-
-if the pattern starts with C<.*>;
-
-=item C<with eval>
-
-if the pattern contain eval-groups (see L<perlre/(?{ code })>);
-
-=item C<anchored(TYPE)>
-
-if the pattern may
-match only at a handful of places (with C<TYPE> being
-C<BOL>, C<MBOL>, or C<GPOS>, see the table below).
-
-=back
-
-If a substring is known to match at end-of-line only, it may be
-followed by C<$>, as in C<floating `k'$>.
-
-The optimizer-specific info is used to avoid entering (a slow) RE
-engine on strings which will definitely not match. If C<isall> flag
-is set, a call to the RE engine may be avoided even when optimizer
-found an appropriate place for the match.
-
-The rest of the output contains the list of I<nodes> of the compiled
-form of the RE. Each line has format
-
-C< >I<id>: I<TYPE> I<OPTIONAL-INFO> (I<next-id>)
-
-=head2 Types of nodes
-
-Here is the list of possible types with short descriptions:
-
- # TYPE arg-description [num-args] [longjump-len] DESCRIPTION
-
- # Exit points
- END no End of program.
- SUCCEED no Return from a subroutine, basically.
-
- # Anchors:
- BOL no Match "" at beginning of line.
- MBOL no Same, assuming multiline.
- SBOL no Same, assuming singleline.
- EOS no Match "" at end of string.
- EOL no Match "" at end of line.
- MEOL no Same, assuming multiline.
- SEOL no Same, assuming singleline.
- BOUND no Match "" at any word boundary
- BOUNDL no Match "" at any word boundary
- NBOUND no Match "" at any word non-boundary
- NBOUNDL no Match "" at any word non-boundary
- GPOS no Matches where last m//g left off.
-
- # [Special] alternatives
- ANY no Match any one character (except newline).
- SANY no Match any one character.
- ANYOF sv Match character in (or not in) this class.
- ALNUM no Match any alphanumeric character
- ALNUML no Match any alphanumeric char in locale
- NALNUM no Match any non-alphanumeric character
- NALNUML no Match any non-alphanumeric char in locale
- SPACE no Match any whitespace character
- SPACEL no Match any whitespace char in locale
- NSPACE no Match any non-whitespace character
- NSPACEL no Match any non-whitespace char in locale
- DIGIT no Match any numeric character
- NDIGIT no Match any non-numeric character
-
- # BRANCH The set of branches constituting a single choice are hooked
- # together with their "next" pointers, since precedence prevents
- # anything being concatenated to any individual branch. The
- # "next" pointer of the last BRANCH in a choice points to the
- # thing following the whole choice. This is also where the
- # final "next" pointer of each individual branch points; each
- # branch starts with the operand node of a BRANCH node.
- #
- BRANCH node Match this alternative, or the next...
-
- # BACK Normal "next" pointers all implicitly point forward; BACK
- # exists to make loop structures possible.
- # not used
- BACK no Match "", "next" ptr points backward.
-
- # Literals
- EXACT sv Match this string (preceded by length).
- EXACTF sv Match this string, folded (prec. by length).
- EXACTFL sv Match this string, folded in locale (w/len).
-
- # Do nothing
- NOTHING no Match empty string.
- # A variant of above which delimits a group, thus stops optimizations
- TAIL no Match empty string. Can jump here from outside.
-
- # STAR,PLUS '?', and complex '*' and '+', are implemented as circular
- # BRANCH structures using BACK. Simple cases (one character
- # per match) are implemented with STAR and PLUS for speed
- # and to minimize recursive plunges.
- #
- STAR node Match this (simple) thing 0 or more times.
- PLUS node Match this (simple) thing 1 or more times.
-
- CURLY sv 2 Match this simple thing {n,m} times.
- CURLYN no 2 Match next-after-this simple thing
- # {n,m} times, set parenths.
- CURLYM no 2 Match this medium-complex thing {n,m} times.
- CURLYX sv 2 Match this complex thing {n,m} times.
-
- # This terminator creates a loop structure for CURLYX
- WHILEM no Do curly processing and see if rest matches.
-
- # OPEN,CLOSE,GROUPP ...are numbered at compile time.
- OPEN num 1 Mark this point in input as start of #n.
- CLOSE num 1 Analogous to OPEN.
-
- REF num 1 Match some already matched string
- REFF num 1 Match already matched string, folded
- REFFL num 1 Match already matched string, folded in loc.
-
- # grouping assertions
- IFMATCH off 1 2 Succeeds if the following matches.
- UNLESSM off 1 2 Fails if the following matches.
- SUSPEND off 1 1 "Independent" sub-RE.
- IFTHEN off 1 1 Switch, should be preceeded by switcher .
- GROUPP num 1 Whether the group matched.
-
- # Support for long RE
- LONGJMP off 1 1 Jump far away.
- BRANCHJ off 1 1 BRANCH with long offset.
-
- # The heavy worker
- EVAL evl 1 Execute some Perl code.
-
- # Modifiers
- MINMOD no Next operator is not greedy.
- LOGICAL no Next opcode should set the flag only.
-
- # This is not used yet
- RENUM off 1 1 Group with independently numbered parens.
-
- # This is not really a node, but an optimized away piece of a "long" node.
- # To simplify debugging output, we mark it as if it were a node
- OPTIMIZED off Placeholder for dump.
-
-=head2 Run-time output
-
-First of all, when doing a match, one may get no run-time output even
-if debugging is enabled. this means that the RE engine was never
-entered, all of the job was done by the optimizer.
-
-If RE engine was entered, the output may look like this:
-
- Matching `[bc]d(ef*g)+h[ij]k$' against `abcdefg__gh__'
- Setting an EVAL scope, savestack=3
- 2 <ab> <cdefg__gh_> | 1: ANYOF
- 3 <abc> <defg__gh_> | 11: EXACT <d>
- 4 <abcd> <efg__gh_> | 13: CURLYX {1,32767}
- 4 <abcd> <efg__gh_> | 26: WHILEM
- 0 out of 1..32767 cc=effff31c
- 4 <abcd> <efg__gh_> | 15: OPEN1
- 4 <abcd> <efg__gh_> | 17: EXACT <e>
- 5 <abcde> <fg__gh_> | 19: STAR
- EXACT <f> can match 1 times out of 32767...
- Setting an EVAL scope, savestack=3
- 6 <bcdef> <g__gh__> | 22: EXACT <g>
- 7 <bcdefg> <__gh__> | 24: CLOSE1
- 7 <bcdefg> <__gh__> | 26: WHILEM
- 1 out of 1..32767 cc=effff31c
- Setting an EVAL scope, savestack=12
- 7 <bcdefg> <__gh__> | 15: OPEN1
- 7 <bcdefg> <__gh__> | 17: EXACT <e>
- restoring \1 to 4(4)..7
- failed, try continuation...
- 7 <bcdefg> <__gh__> | 27: NOTHING
- 7 <bcdefg> <__gh__> | 28: EXACT <h>
- failed...
- failed...
-
-The most significant information in the output is about the particular I<node>
-of the compiled RE which is currently being tested against the target string.
-The format of these lines is
-
-C< >I<STRING-OFFSET> <I<PRE-STRING>> <I<POST-STRING>> |I<ID>: I<TYPE>
-
-The I<TYPE> info is indented with respect to the backtracking level.
-Other incidental information appears interspersed within.
-
-=cut
Support for non-Unix platforms has been improved.
+=head2 perldoc
+
+C<perldoc> has been reworked to avoid possible security holes.
+It will not by default let itself be run as the superuser, but you
+may still use the B<-U> switch to try to make it drop privileges
+first.
+
+=head2 The Perl Debugger
+
+Many bug fixes and enhancements were added to F<perl5db.pl>, the
+Perl debugger. The help documentation was rearranged. New commands
+include C<< < ? >>, C<< > ? >>, and C<< { ? >> to list out current
+actions, C<man I<docpage>> to run your doc viewer on some perl
+docset, and support for quoted options. The help information was
+rearranged, and should be viewable once again if you're using B<less>
+as your pager. A serious security hole was plugged--you should
+immediately remove all older versions of the Perl debugger as
+installed in previous releases, all the way back to perl3, from
+your system to avoid being bitten by this.
+
=head1 Documentation Changes
=over 4
An introduction to using the Perl Compiler suite.
+=item perldebug.pod
+
+All material unrelated to running the Perl debugger, plus all
+low-level guts-like details that risked crushing the casual user
+of the debugger, have been relocated from the old manpage to the
+next entry below.
+
+=item perldebguts.pod
+
+This new manpage contains excessively low-level material not related
+to the Perl debugger, but slightly related to debugging Perl itself.
+It also contains some arcane internal details of how the debugging
+process works that may only be of interest to developers of Perl
+debuggers.
+
=item perlfilter.pod
An introduction to writing Perl source filters.
overloading allows user-defined behaviors for numbers, such as operations
over arbitrarily large integers, floating points numbers with arbitrary
precision, operations over "exotic" numbers such as modular arithmetic or
-p-adic arithmetic, and so on. See L<perlovl> for details.
+p-adic arithmetic, and so on. See L<overload> for details.
=head1 Storing numbers
=head1 SEE ALSO
-L<perlovl>
+L<overload>
=back
+=head1 Supported Platforms
+
+As of early March 2000 (the Perl release 5.6.0), the following
+platforms are able to build Perl from the standard source code
+distribution available at http://www.perl.com/CPAN/src/index.html
+
+ AIX
+ DOS DJGPP 1)
+ FreeBSD
+ HP-UX
+ IRIX
+ Linux
+ LynxOS
+ MachTen
+ MPE/iX
+ NetBSD
+ OpenBSD
+ OS/2
+ Rhapsody/Darwin 2)
+ Solaris
+ Tru64 UNIX 3)
+ UNICOS
+ UNICOS/mk
+ VMS
+ VOS
+ Windows 3.1 1)
+ Windows 95 1) 4)
+ Windows 98 1) 4)
+ Windows NT 1) 4)
+
+ 1) in DOS mode either the DOS or OS/2 ports can be used
+ 2) new in 5.6.0: the BSD/NeXT-based UNIX of Mac OS X
+ 3) formerly known as Digital UNIX and before that DEC OSF/1
+ 4) compilers: Borland, Cygwin, Mingw32 EGCS/GCC, VC++
+
+The following platforms worked for the previous major release
+(5.005_03 being the latest maintenance release of that, as of early
+March 2000), but be did not manage to test these in time for the 5.6.0
+release of Perl. There is a very good chance that these will work
+just fine with 5.6.0.
+
+ A/UX
+ BeOS
+ BSD/OS
+ DG/UX
+ DYNIX/ptx
+ DomainOS
+ Hurd
+ NextSTEP
+ OpenSTEP
+ PowerMAX
+ QNX
+ SCO ODT/OSR
+ SunOS
+ SVR4
+ Ultrix
+
+The following platform worked for the previous major release (5.005_03
+being the latest maintenance release of that, as of early March 2000).
+However, standardization on UTF-8 as the internal string representation
+in 5.6.0 has introduced incompatibilities in this EBCDIC platform.
+Support for this platform may be enabled in a future release:
+
+ OS390 1)
+
+ 1) Previously known as MVS, or OpenEdition MVS.
+
+Strongly related to the OS390 platform by also being EBCDIC-based
+mainframe platforms are the following platforms:
+
+ BS2000
+ VM/ESA
+
+These are also not expected to work under 5.6.0 for the same reasons
+as OS390. Contact the mailing list perl-mvs@perl.org for more details.
+
+MacOS (Classic, pre-X) is almost 5.6.0-ready; building from the source
+does work with 5.6.0, but additional MacOS specific source code is needed
+for a complete port. Contact the mailing list macperl-porters@macperl.org
+for more more information.
+
+The following platforms have been known to build Perl from source in
+the past, but we haven't been able to verify their status for the
+current release, either because the hardware/software platforms are
+rare or because we don't have an active champion on these
+platforms--or both:
+
+ 3b1
+ AmigaOS
+ ConvexOS
+ CX/UX
+ DC/OSx
+ DDE SMES
+ DOS EMX
+ Dynix
+ EP/IX
+ ESIX
+ FPS
+ GENIX
+ Greenhills
+ ISC
+ MachTen 68k
+ MiNT
+ MPC
+ NEWS-OS
+ Opus
+ Plan 9
+ PowerUX
+ RISC/os
+ Stellar
+ SVR2
+ TI1500
+ TitanOS
+ Unisys Dynix
+ Unixware
+
+Support for the following platform is planned for a future Perl release:
+
+ Netware
+
+The following platforms have their own source code distributions and
+binaries available via http://www.perl.com/CPAN/ports/index.html:
+
+ Perl release
+
+ AS/400 5.003
+ Netware 5.003_07
+ Tandem Guardian 5.004
+
+The following platforms have only binaries available via
+http://www.perl.com/CPAN/ports/index.html:
+
+ Perl release
+
+ Acorn RISCOS 5.005_02
+ AOS 5.002
+ LynxOS 5.004_02
+
+Although we do suggest that you always build your own Perl from
+the source code, both for maximal configurability and for security,
+in case you are in a hurry you can check
+http://www.perl.com/CPAN/ports/index.html for binary distributions.
+
=head1 AUTHORS / CONTRIBUTORS
Abigail <abigail@fnx.com>,
projects / p5sagit/p5-mst-13.2.git / commitdiff