X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperldebug.pod;h=0c61b74350bbf30e3af5941cece184a47f05f3a5;hb=11155c9133a662d0930b7253d2ffdaeee3dcc771;hp=5d67ba41a6c8cf0ab0b9f6c6b8bb8d1bf6d273eb;hpb=5f05dabc4054964aa3b10f44f8468547f051cdf8;p=p5sagit%2Fp5-mst-13.2.git diff --git a/pod/perldebug.pod b/pod/perldebug.pod index 5d67ba4..0c61b74 100644 --- a/pod/perldebug.pod +++ b/pod/perldebug.pod @@ -60,12 +60,17 @@ it's run through your pager, as in DB> |h +You may change the pager which is used via C command. + =item p expr Same as C in the current package. In particular, because this is just Perl's own B function, this means that nested data structures and objects are not dumped, unlike with the C command. +The C filehandle is opened to F, regardless of +where STDOUT may be redirected to. + =item x expr Evaluates its expression in list context and dumps out the result @@ -105,10 +110,12 @@ Single step. Executes until it reaches 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 +=item n [expr] Next. Executes over subroutine calls, until it reaches the beginning -of the next statement. +of the next statement. If an expression is supplied that includes +function calls, those functions will be executed with stops before +each statement. =item ECRE @@ -129,7 +136,7 @@ List C lines starting at C. =item l min-max -List lines C through C. +List lines C through C. C is synonymous to C<->. =item l line @@ -154,7 +161,9 @@ print it out. =item f filename -Switch to viewing a different file. +Switch to viewing a different file or eval statement. If C +is not a full filename as found in values of %INC, it is considered as +a regexp. =item /pattern/ @@ -235,7 +244,13 @@ Set breakpoint at first line of subroutine after it is compiled. =item b load filename -Set breakpoint at the first executed line of the file. +Set breakpoint at the first executed line of the file. Filename should +be a full name as found in values of %INC. + +=item b compile subname + +Sets breakpoint at the first statement executed after the subroutine +is compiled. =item d [line] @@ -251,29 +266,11 @@ Delete all installed breakpoints. Set an action to be done before the line is executed. The sequence of steps taken by the debugger is -=over 3 - -=item 1 - -check for a breakpoint at this line - -=item 2 - -print the line if necessary (tracing) - -=item 3 - -do any actions associated with that line - -=item 4 - -prompt user if at a breakpoint or in single-step - -=item 5 - -evaluate line - -=back + 1. check for a breakpoint at this line + 2. print the line if necessary (tracing) + 3. do any actions associated with that line + 4. prompt user if at a breakpoint or in single-step + 5. evaluate line For example, this will print out C<$foo> every time line 53 is passed: @@ -291,34 +288,41 @@ be abbreviated. Several options can be listed. =over 12 -=item recallCommand, ShellBang +=item C, C The characters used to recall command or spawn shell. By default, these are both set to C. -=item pager +=item C Program to use for output of pager-piped commands (those beginning with a C<|> character.) By default, C<$ENV{PAGER}> will be used. -=item tkRunning +=item C Run Tk while prompting (with ReadLine). -=item signalLevel, warnLevel, dieLevel +=item C, C, C -Level of verbosity. +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. -=item AutoTrace +To disable this behaviour, set these values to 0. If C is 2, +then the messages which will be caught by surrounding C are also +printed. -Where to print all the breakable points in the executed program -(similar to C command, but can be put into C). +=item C -=item LineInfo +Trace mode (similar to C command, but can be put into +C). -File or pipe to print line number info to. If it is a -pipe, then a short, "emacs like" message is used. +=item C + +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. =item C @@ -335,7 +339,14 @@ C is false, messages are printed on entry only. (Printing on exit may be useful if inter(di)spersed with other messages.) If C, arguments to functions are printed as well as the -context and caller info. +context and caller info. If C, overloaded C and +Cd C are enabled on the printed arguments. The length at +which the argument list is truncated is governed by the next option: + +=item C + +length at which the argument list is truncated when C option's +bit 4 is set. =back @@ -344,29 +355,38 @@ commands: =over 12 -=item arrayDepth, hashDepth +=item C, C Print only first N elements ('' for all). -=item compactDump, veryCompact +=item C, C -Change style of array and hash dump. +Change style of array and hash dump. If C, short array +may be printed on one line. -=item globPrint +=item C Whether to print contents of globs. -=item DumpDBFiles +=item C Dump arrays holding debugged files. -=item DumpPackages +=item C Dump symbol tables of packages. -=item quote, HighBit, undefPrint +=item C, C, C + +Change style of string dump. Default value of C is C, 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. + +=item C -Change style of string dump. +I rudimentally per-package memory usage dump. Calculates total +size of strings in variables in the package. =back @@ -376,7 +396,7 @@ C, and C there. Example rc file: - &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. (If you interrupt it, you would better reset @@ -388,16 +408,9 @@ C to something "interactive"!) The TTY to use for debugging I/O. -=item noTTY - -If set, goes in C mode. On interrupt if TTY is not set uses the -value of C or "/tmp/perldbtty$$" to find TTY using -C. Current variant is to have the name of TTY in this -file. - =item C -If set, goes in C mode, and would not connect to a TTY. If +If set, goes in C mode, and would not connect to a TTY. If interrupt (or if control goes to debugger via explicit setting of $DB::signal or $DB::single from the Perl script), connects to a TTY specified by the C option at startup, or to a TTY found at @@ -405,7 +418,7 @@ runtime using C module of your choice. This module should implement a method C which returns an object with two methods: C and C, returning two filehandles to use -for debugging input and output correspondingly. Method C may +for debugging input and output correspondingly. Method C may inspect an argument which is a value of C<$ENV{PERLDB_NOTTY}> at startup, or is C<"/tmp/perldbtty$$"> otherwise. @@ -423,18 +436,18 @@ programmatically by setting $DB::signal or $DB::single. Here's an example of using the C<$ENV{PERLDB_OPTS}> variable: - $ PERLDB_OPTS="N f=2" perl -d myprogram + $ PERLDB_OPTS="N f=2" perl -d myprogram will run the script C without human intervention, printing out the call tree with entry and exit points. Note that C is -equivalent to C. Note also that at the moment when +equivalent to C. 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 options). Other examples may include - $ PERLDB_OPTS="N f A L=listing" perl -d myprogram + $ PERLDB_OPTS="N f A L=listing" perl -d myprogram - runs script non-interactively, printing info on each entry into a subroutine and each executed line into the file F. (If you @@ -442,16 +455,18 @@ interrupt it, you would better reset C to something "interactive"!) - $ env "PERLDB_OPTS=R=0 TTY=/dev/ttyc" perl -d myprogram + $ env "PERLDB_OPTS=R=0 TTY=/dev/ttyc" perl -d myprogram may be useful for debugging a program which uses C -itself. Do not forget detach shell from the TTY in the window which +itself. Do not forget detach shell from the TTY in the window which corresponds to F, say, by issuing a command like - $ sleep 1000000 + $ sleep 1000000 See L<"Debugger Internals"> below for more details. +=over 12 + =item E [ command ] Set an action (Perl command) to happen before every debugger prompt. @@ -516,7 +531,7 @@ Quit. ("quit" doesn't work for this.) This is the only supported way to exit the debugger, though typing C twice may do it too. Set an Cption C to 0 if you want to be able to I the end the script. You may also need to set C<$finished> to 0 at +off> the end the script. You may also need to set C<$finished> to 0 at some moment if you want to step through global destruction. =item R @@ -543,20 +558,34 @@ output, such as =item = [alias value] -Define a command alias, or list current aliases. +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 p expr +=item m expr + +The expression is evaluated, and the methods which may be applied to +the result are listed. + +=item m package -Same as C. The DB::OUT filehandle is opened to -/dev/tty, regardless of where STDOUT may be redirected to. +The methods which may be applied to objects in the C are listed. =back +=head2 Debugger input/output + +=over 8 + +=item Prompt + The debugger prompt is something like DB<8> @@ -573,9 +602,12 @@ 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 command. +=item Multi-line commands + If you want to enter a multi-line command, such as a subroutine -definition with several statements, you may escape the newline that would -normally end the debugger command with a backslash. Here's an example: +definition with several statements, or a format, you may escape the +newline that would normally end the debugger command with a backslash. +Here's an example: DB<1> for (1..4) { \ cont: print "ok\n"; \ @@ -588,7 +620,10 @@ normally end the debugger command with a backslash. Here's an example: Note that this business of escaping a newline is specific to interactive commands typed into the debugger. -Here's an example of what a stack back-trace might look like: +=item Stack backtrace + +Here's an example of what a stack back-trace via C command might +look like: $ = main::infested called from file `Ambulation.pm' line 10 @ = Ambulation::legs(1, 2, 3, 4) called from file `camel_flea' line 7 @@ -605,6 +640,160 @@ I file with four arguments. The last stack frame shows that C was called in a scalar context, also from I, but from line 4. +Note that if you execute C command from inside an active C +statement, the backtrace will contain both C> +frame and an C>) frame. + +=item Listing + +Listing given via different flavors of C command looks like this: + + DB<<13>> l + 101: @i{@i} = (); + 102:b @isa{@i,$pack} = () + 103 if(exists $i{$prevpack} || exists $isa{$pack}); + 104 } + 105 + 106 next + 107==> if(exists $isa{$pack}); + 108 + 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, with actions by C, and the +next executed line is marked by C<==E>. + +=item Frame listing + +When C 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=1 N" perl -d -V + +=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), 'PATCHLEVEL') from lib/Config.pm:574 + in $=Config::FETCH(ref(Config), '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), 'PATCHLEVEL') from lib/Config.pm:574 + out $=Config::FETCH(ref(Config), 'PATCHLEVEL') from lib/Config.pm:574 + in $=Config::FETCH(ref(Config), '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 $=Config::FETCH('Config=HASH(0x1aa444)', 'baserev') from lib/Config.pm:574 + +=back + +In all the cases indentation of lines shows the call tree, if bit 2 of +C is set, then a line is printed on exit from a subroutine as +well, if bit 4 is set, then the arguments are printed as well as the +caller info, if bit 8 is set, the arguments are printed even if they +are tied or references. + +When a package is compiled, a line like this + + Package lib/Carp.pm. + +is printed with proper indentation. + +=back + +=head2 Debugging compile-time statements + If you have any compile-time executable statements (code within a BEGIN block or a C statement), these will C be stopped by debugger, although Cs will (and compile-time statements can be traced @@ -620,10 +809,19 @@ just typed the C command, whereas a value of 1 means the C command. The C<$DB::trace> variable should be set to 1 to simulate having typed the C command. +Another way to debug compile-time code is to start debugger, set a +breakpoint on I of some module thusly + + DB<7> b load f:/perllib/lib/Carp.pm + Will stop on load of `f:/perllib/lib/Carp.pm'. + +and restart debugger by C command (if possible). One can use C for the same purpose. + =head2 Debugger Customization Most probably you not want to modify the debugger, it contains enough -hooks to satisfy most needs. You may change the behaviour of debugger +hooks to satisfy most needs. You may change the behaviour of debugger from the debugger itself, using Cptions, from the command line via C environment variable, and from I. @@ -640,10 +838,10 @@ One changes options from F<.perldb> file via calls like this one; parse_options("NonStop=1 LineInfo=db.out AutoTrace=1 frame=2"); -(the code is executed in the package C). Note that F<.perldb> is -processed before processing C. If F<.perldb> defines the +(the code is executed in the package C). Note that F<.perldb> is +processed before processing C. If F<.perldb> defines the subroutine C, it is called after all the debugger -initialization ends. F<.perldb> may be contained in the current +initialization ends. F<.perldb> may be contained in the current directory, or in the C/C directory. If you want to modify the debugger, copy F from the Perl @@ -663,6 +861,10 @@ the Term::ReadKey and Term::ReadLine modules from CPAN, you will have full editing capabilities much like GNU I(3) provides. Look for these in the F directory on CPAN. +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 installed on your system, it can interact with @@ -699,9 +901,9 @@ in that profile. =head2 Debugger support in perl -When you call the B function from package DB, Perl sets the -C<@DB::args> array to contain the arguments that stack frame was called -with. +When you call the B function (see L) from the +package DB, Perl sets the array @DB::args to contain the arguments the +corresponding stack frame was called with. If perl is run with B<-d> option, the following additional features are enabled: @@ -717,48 +919,48 @@ application. =item * The array C<@{"_<$filename"}> is the line-by-line contents of -$filename for all the compiled files. Same for Ced strings which -contain subroutines, or which are currently executed. The C<$filename> +$filename for all the compiled files. Same for Ced strings which +contain subroutines, or which are currently executed. The C<$filename> for Ced strings looks like C<(eval 34)>. =item * The hash C<%{"_<$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 +to the whole hash). Only true/false is important to Perl, though the values used by F have the form -C<"$break_condition\0$action">. Values are magical in numeric context: +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 C<$filename> for Ced strings looks like +currently executed. The C<$filename> for Ced strings looks like C<(eval 34)>. =item * -The scalar C<${"_<$filename"}> contains C<"_<$filename">. Same for +The scalar C<${"_<$filename"}> contains C<"_<$filename">. Same for evaluated strings which contain subroutines, or which are currently -executed. The C<$filename> for Ced strings looks like C<(eval +executed. The C<$filename> for Ced strings looks like C<(eval 34)>. =item * After each Cd file is compiled, but before it is executed, C is called (if subroutine -C exists). Here the $filename is the expanded name of +C exists). Here the $filename is the expanded name of the Cd file (as found in values of C<%INC>). =item * After each subroutine C is compiled existence of -C<$DB::postponed{subname}> is checked. If this key exists, +C<$DB::postponed{subname}> is checked. If this key exists, C is called (if subroutine C exists). =item * A hash C<%DB::sub> is maintained, with keys being subroutine names, -values having the form C. C has +values having the form C. C has the form C<(eval 31)> for subroutines defined inside Cs. =item * @@ -768,7 +970,7 @@ a breakpoint, a call to C is performed if any one of variables $DB::trace, $DB::single, or $DB::signal is true. (Note that these variables are not Cizable.) This feature is disabled when the control is inside C or functions called from it (unless -C<$^D & 1 EE 30>). +C<$^D & (1EE30)>). =item * @@ -780,10 +982,42 @@ in the package C.) =back Note that no subroutine call is possible until C<&DB::sub> is defined -(for subroutines outside of package C). (In fact, for the -standard debugger the same is true if C<$DB::deep> (how many levels of -recursion deep into the debugger you can go before a mandatory break) -is not defined.) +(for subroutines outside of package C). (This restriction is +recently lifted.) + +(In fact, for the standard debugger the same is true if C<$DB::deep> +(how many levels of recursion deep into the debugger you can go before +a mandatory break) is not defined.) + +With the recent updates the minimal possible debugger consists of one +line + + sub DB::DB {} + +which is quite handy as contents of C environment +variable: + + env "PERL5DB=sub DB::DB {}" perl -d your-script + +Another (a little bit more useful) minimal debugger can be created +with the only line being + + sub DB::DB {print ++$i; scalar } + +This debugger would print the sequential number of encountered +statement, and would wait for your C to continue. + +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. =head2 Debugger Internals @@ -797,21 +1031,21 @@ PERLDB_OPTS and parses it as a rest of C line in debugger prompt. It also maintains magical internal variables, such as C<@DB::dbline>, C<%DB::dbline>, which are aliases for C<@{"::_ -C<%{"::_. Here C is the currently +C<%{"::_. Here C is the currently selected (with the debugger's C command, or by flow of execution) file. -Some functions are provided to simplify customization. See L<"Debugger -Customization"> for description of C. The +Some functions are provided to simplify customization. See L<"Debugger +Customization"> for description of C. The function C skips the specified number of frames, and returns an array containing info about the caller -frames (all if C is missing). Each entry is a hash with keys +frames (all if C is missing). Each entry is a hash with keys C (C<$> or C<@>), C (subroutine name, or info about eval), C (C or a reference to an array), C, and C. The function C prints -formatted info about caller frames. The last two functions may be +formatted info about caller frames. The last two functions may be convenient as arguments to C>, CE> commands. =head2 Other resources