=head1 NAME
-perldelta - what's new for perl5.004
+perldelta - what's new for perl5.005
=head1 DESCRIPTION
-This document describes differences between the 5.003 release (as
-documented in I<Programming Perl>, second edition--the Camel Book) and
-this one.
+This document describes differences between the 5.004 release and this one.
-=head1 Supported Environments
-
-Perl5.004 builds out of the box on Unix, Plan9, LynxOS, VMS, OS/2,
-QNX, and AmigaOS.
+=head1 Incompatible Changes
=head1 Core Changes
-Most importantly, many bugs were fixed. See the F<Changes>
-file in the distribution for details.
-
-=head2 Compilation Option: Binary Compatibility With 5.003
-
-There is a new Configure question that asks if you want to maintain
-binary compatibility with Perl 5.003. If you choose binary
-compatibility, you do not have to recompile your extensions, but you
-might have symbol conflicts if you embed Perl in another application,
-just as in the 5.003 release. By default, binary compatibility
-is preserved at the expense of symbol table pollution.
-
-=head2 New Opcode Module and Revised Safe Module
-
-A new Opcode module supports the creation, manipulation and
-application of opcode masks. The revised Safe module has a new API
-and is implemented using the new Opcode module. Please read the new
-Opcode and Safe documentation.
-
-=head2 Internal Change: FileHandle Deprecated
-
-Filehandles are now stored internally as type IO::Handle.
-Although C<use FileHandle> and C<*STDOUT{FILEHANDLE}>
-are still supported for backwards compatibility,
-C<use IO::Handle> (or C<IO::Seekable> or C<IO::File>) and
-C<*STDOUT{IO}> are the way of the future.
-
-=head2 Internal Change: PerlIO internal IO abstraction interface
-
-It is now possible to build Perl with AT&T's sfio IO package
-instead of stdio. See L<perlapio> for more details, and
-the F<INSTALL> file for how to use it.
-
-=head2 New and Changed Built-in Variables
-
-=over
-
-=item $^E
-
-Extended error message on some platforms. (Also known as
-$EXTENDED_OS_ERROR if you C<use English>).
-
-=item $^H
-
-The current set of syntax checks enabled by C<use strict>. See the
-documentation of C<strict> for more details. Not actually new, but
-newly documented.
-Because it is intended for internal use by Perl core components,
-there is no C<use English> long name for this variable.
-
-=item $^M
-
-By default, running out of memory it is not trappable. However, if
-compiled for this, Perl may use the contents of C<$^M> as an emergency
-pool after die()ing with this message. Suppose that your Perl were
-compiled with -DEMERGENCY_SBRK and used Perl's malloc. Then
-
- $^M = 'a' x (1<<16);
-
-would allocate a 64K buffer for use when in emergency.
-See the F<INSTALL> file for information on how to enable this option.
-As a disincentive to casual use of this advanced feature,
-there is no C<use English> long name for this variable.
-
-=item $^S
-
-The status returned by the last pipe close, back-tick (C<``>) command, or
-system() operator, in the native system format. On UNIX and UNIX-like
-systems, C<$^S> is a synonym for C<$?>. Elsewhere, C<$^S> can be used to
-determine aspects of child status that are system-specific. Check C<$^O>
-before using this variable. (Mnemonic: System-Specific Subprocess Status.
-Also known as $SYSTEM_CHILD_STATUS if you C<use English>.)
-
-=back
-
-=head2 New and Changed Built-in Functions
-
-=over
-
-=item delete on slices
-
-This now works. (e.g. C<delete @ENV{'PATH', 'MANPATH'}>)
-
-=item flock
-
-is now supported on more platforms, and prefers fcntl
-to lockf when emulating.
-
-=item keys as an lvalue
-
-As an lvalue, C<keys> allows you to increase the number of hash buckets
-allocated for the given associative array. This can gain you a measure
-of efficiency if you know the hash is going to get big. (This is
-similar to pre-extending an array by assigning a larger number to
-$#array.) If you say
-
- keys %hash = 200;
-
-then C<%hash> will have at least 200 buckets allocated for it. These
-buckets will be retained even if you do C<%hash = ()>; use C<undef
-%hash> if you want to free the storage while C<%hash> is still in scope.
-You can't shrink the number of buckets allocated for the hash using
-C<keys> in this way (but you needn't worry about doing this by accident,
-as trying has no effect).
-
-=item my() in Control Structures
-
-You can now use my() (with or without the parentheses) in the control
-expressions of control structures such as:
-
- while (my $line = <>) {
- $line = lc $line;
- } continue {
- print $line;
- }
-
- if ((my $answer = <STDIN>) =~ /^y(es)?$/i) {
- user_agrees();
- } elsif ($answer =~ /^n(o)?$/i) {
- user_disagrees();
- } else {
- chomp $answer;
- die "`$answer' is neither `yes' nor `no'";
- }
-
-Also, you can declare a foreach loop control variable as lexical by
-preceding it with the word "my". For example, in:
-
- foreach my $i (1, 2, 3) {
- some_function();
- }
-
-$i is a lexical variable, and the scope of $i extends to the end of
-the loop, but not beyond it.
-
-Note that you still cannot use my() on global punctuation variables
-such as $_ and the like.
-
-=item unpack() and pack()
-
-A new format 'w' represents a BER compressed integer (as defined in
-ASN.1). Its format is a sequence of one or more bytes, each of which
-provides seven bits of the total value, with the most significant
-first. Bit eight of each byte is set, except for the last byte, in
-which bit eight is clear.
-
-=item use VERSION
-
-If the first argument to C<use> is a number, it is treated as a version
-number instead of a module name. If the version of the Perl interpreter
-is less than VERSION, then an error message is printed and Perl exits
-immediately. Because C<use> occurs at compile time, this check happens
-immediately during the compilation process, unlike C<require VERSION>,
-which waits until run-time for the check. This is often useful if you
-need to check the current Perl version before C<use>ing library modules
-which have changed in incompatible ways from older versions of Perl.
-(We try not to do this more than we have to.)
-
-=item use Module VERSION LIST
-
-If the VERSION argument is present between Module and LIST, then the
-C<use> will call the VERSION method in class Module with the given
-version as an argument. The default VERSION method, inherited from
-the Universal class, croaks if the given version is larger than the
-value of the variable $Module::VERSION. (Note that there is not a
-comma after VERSION!)
-
-This version-checking mechanism is similar to the one currently used
-in the Exporter module, but it is faster and can be used with modules
-that don't use the Exporter. It is the recommended method for new
-code.
-
-=item prototype(FUNCTION)
-
-Returns the prototype of a function as a string (or C<undef> if the
-function has no prototype). FUNCTION is a reference to or the name of the
-function whose prototype you want to retrieve.
-(Not actually new; just never documented before.)
-
-=item $_ as Default
-
-Functions documented in the Camel to default to $_ now in
-fact do, and all those that do are so documented in L<perlfunc>.
-
-=item C<m//g> does not trigger a pos() reset on failure
-
-The C<m//g> match iteration construct used to reset the iteration
-when it failed to match (so that the next C<m//g> match would start at
-the beginning of the string). You now have to explicitly do a
-C<pos $str = 0;> to reset the "last match" position, or modify the
-string in some way. This change makes it practical to chain C<m//g>
-matches together in conjunction with ordinary matches using the C<\G>
-zero-width assertion. See L<perlop> and L<perlre>.
-
-=item nested C<sub{}> closures work now
-
-Prior to the 5.004 release, nested anonymous functions
-didn't work right. They do now.
-
-=item formats work right on changing lexicals
-
-Just like anonymous functions that contain lexical variables
-that change (like a lexical index variable for a C<foreach> loop),
-formats now work properly. For example, this silently failed
-before, and is fine now:
-
- my $i;
- foreach $i ( 1 .. 10 ) {
- format =
- my i is @#
- $i
- .
- write;
- }
-
-=back
-
-=head2 New Built-in Methods
-
-The C<UNIVERSAL> package automatically contains the following methods that
-are inherited by all other classes:
-
-=over
-
-=item isa(CLASS)
-
-C<isa> returns I<true> if its object is blessed into a sub-class of C<CLASS>
-
-C<isa> is also exportable and can be called as a sub with two arguments. This
-allows the ability to check what a reference points to. Example:
-
- use UNIVERSAL qw(isa);
-
- if(isa($ref, 'ARRAY')) {
- ...
- }
-
-=item can(METHOD)
-
-C<can> checks to see if its object has a method called C<METHOD>,
-if it does then a reference to the sub is returned; if it does not then
-I<undef> is returned.
-
-=item VERSION( [NEED] )
-
-C<VERSION> returns the version number of the class (package). If the
-NEED argument is given then it will check that the current version (as
-defined by the $VERSION variable in the given package) not less than
-NEED; it will die if this is not the case. This method is normally
-called as a class method. This method is called automatically by the
-C<VERSION> form of C<use>.
-
- use A 1.2 qw(some imported subs);
- # implies:
- A->VERSION(1.2);
-
-=item class()
-
-C<class> returns the class name of its object.
-
-=item is_instance()
-
-C<is_instance> returns true if its object is an instance of some
-class, false if its object is the class (package) itself. Example
-
- A->is_instance(); # False
-
- $var = 'A';
- $var->is_instance(); # False
-
- $ref = bless [], 'A';
- $ref->is_instance(); # True
-
-This can be useful for methods that wish to easily distinguish
-whether they were invoked as class or as instance methods.
-
- sub some_meth {
- my $classname = shift;
- if ($classname->is_instance()) {
- die "unexpectedly called as instance not class method";
- }
- .....
- }
-
-=back
-
-B<NOTE:> C<can> directly uses Perl's internal code for method lookup, and
-C<isa> uses a very similar method and caching strategy. This may cause
-strange effects if the Perl code dynamically changes @ISA in any package.
-
-You may add other methods to the UNIVERSAL class via Perl or XS code.
-You do not need to C<use UNIVERSAL> in order to make these methods
-available to your program. This is necessary only if you wish to
-have C<isa> available as a plain subroutine in the current package.
-
-=head2 TIEHANDLE Now Supported
-
-See L<perltie> for other kinds of tie()s.
-
-=over
-
-=item TIEHANDLE classname, LIST
-
-This is the constructor for the class. That means it is expected to
-return an object of some sort. The reference can be used to
-hold some internal information.
-
- sub TIEHANDLE {
- print "<shout>\n";
- my $i;
- return bless \$i, shift;
- }
-
-=item PRINT this, LIST
-
-This method will be triggered every time the tied handle is printed to.
-Beyond its self reference it also expects the list that was passed to
-the print function.
-
- sub PRINT {
- $r = shift;
- $$r++;
- return print join( $, => map {uc} @_), $\;
- }
-
-=item READLINE this
-
-This method will be called when the handle is read from. The method
-should return undef when there is no more data.
-
- sub READLINE {
- $r = shift;
- return "PRINT called $$r times\n";
- }
-
-=item DESTROY this
-
-As with the other types of ties, this method will be called when the
-tied handle is about to be destroyed. This is useful for debugging and
-possibly for cleaning up.
-
- sub DESTROY {
- print "</shout>\n";
- }
-
-=back
-
-=item Efficiency Enhancements
-
-All hash keys with the same string are only allocated once, so
-even if you have 100 copies of the same hash, the immutable keys
-never have to be re-allocated.
-
-Functions that have an empty prototype and that do nothing but return
-a fixed value are now inlined (e.g. C<sub PI () { 3.14159 }>).
-
-=head1 Pragmata
-
-Three new pragmatic modules exist:
-
-=over
-
-=item use blib
-
-=item use blib 'dir'
-
-Looks for MakeMaker-like I<'blib'> directory structure starting in
-I<dir> (or current directory) and working back up to five levels of
-parent directories.
-
-Intended for use on command line with B<-M> option as a way of testing
-arbitrary scripts against an uninstalled version of a package.
-
-=item use locale
-
-Tells the compiler to enable (or disable) the use of POSIX locales for
-built-in operations.
-
-When C<use locale> is in effect, the current LC_CTYPE locale is used
-for regular expressions and case mapping; LC_COLLATE for string
-ordering; and LC_NUMERIC for numeric formating in printf and sprintf
-(but B<not> in print). LC_NUMERIC is always used in write, since
-lexical scoping of formats is problematic at best.
-
-Each C<use locale> or C<no locale> affects statements to the end of
-the enclosing BLOCK or, if not inside a BLOCK, to the end of the
-current file. Locales can be switched and queried with
-POSIX::setlocale().
-
-See L<perllocale> for more information.
-
-=item use ops
-
-Disable unsafe opcodes, or any named opcodes, when compiling Perl code.
-
-=back
-
=head1 Modules
-=head2 Installation Directories
-
-The I<installperl> script now places the Perl source files for
-extensions in the architecture-specific library directory, which is
-where the shared libraries for extensions have always been. This
-change is intended to allow administrators to keep the Perl 5.004
-library directory unchanged from a previous version, without running
-the risk of binary incompatibility between extensions' Perl source and
-shared libraries.
-
-=head2 Fcntl
-
-New constants in the existing Fcntl modules are now supported,
-provided that your operating system happens to support them:
-
- F_GETOWN F_SETOWN
- O_ASYNC O_DEFER O_DSYNC O_FSYNC O_SYNC
- O_EXLOCK O_SHLOCK
-
-These constants are intended for use with the Perl operators sysopen()
-and fcntl() and the basic database modules like SDBM_File. For the
-exact meaning of these and other Fcntl constants please refer to your
-operating system's documentation for fcntl() and open().
-
-In addition, the Fcntl module now provides these constants for use
-with the Perl operator flock():
-
- LOCK_SH LOCK_EX LOCK_NB LOCK_UN
-
-These constants are defined in all environments (because where there is
-no flock() system call, Perl emulates it). However, for historical
-reasons, these constants are not exported unless they are explicitly
-requested with the ":flock" tag (e.g. C<use Fcntl ':flock'>).
-
-=head2 Module Information Summary
-
-Brand new modules, arranged by topic rather than strictly
-alphabetically:
-
- CPAN interface to Comprehensive Perl Archive Network
- CPAN::FirstTime create a CPAN configuration file
- CPAN::Nox run CPAN while avoiding compiled extensions
-
- IO.pm Top-level interface to IO::* classes
- IO/File.pm IO::File extension Perl module
- IO/Handle.pm IO::Handle extension Perl module
- IO/Pipe.pm IO::Pipe extension Perl module
- IO/Seekable.pm IO::Seekable extension Perl module
- IO/Select.pm IO::Select extension Perl module
- IO/Socket.pm IO::Socket extension Perl module
-
- Opcode.pm Disable named opcodes when compiling Perl code
-
- ExtUtils/Embed.pm Utilities for embedding Perl in C programs
- ExtUtils/testlib.pm Fixes up @INC to use just-built extension
-
- Fatal.pm Make do-or-die equivalents of functions
- FindBin.pm Find path of currently executing program
-
- Class/Template.pm Structure/member template builder
- File/stat.pm Object-oriented wrapper around CORE::stat
- Net/hostent.pm Object-oriented wrapper around CORE::gethost*
- Net/netent.pm Object-oriented wrapper around CORE::getnet*
- Net/protoent.pm Object-oriented wrapper around CORE::getproto*
- Net/servent.pm Object-oriented wrapper around CORE::getserv*
- Time/gmtime.pm Object-oriented wrapper around CORE::gmtime
- Time/localtime.pm Object-oriented wrapper around CORE::localtime
- Time/tm.pm Perl implementation of "struct tm" for {gm,local}time
- User/grent.pm Object-oriented wrapper around CORE::getgr*
- User/pwent.pm Object-oriented wrapper around CORE::getpw*
-
- Tie/RefHash.pm Base class for tied hashes with references as keys
-
- UNIVERSAL.pm Base class for *ALL* classes
-
-=head2 IO
-
-The IO module provides a simple mechanism to load all of the IO modules at one
-go. Currently this includes:
-
- IO::Handle
- IO::Seekable
- IO::File
- IO::Pipe
- IO::Socket
-
-For more information on any of these modules, please see its
-respective documentation.
-
-=head2 Math::Complex
-
-The Math::Complex module has been totally rewritten, and now supports
-more operations. These are overloaded:
-
- + - * / ** <=> neg ~ abs sqrt exp log sin cos atan2 "" (stringify)
-
-And these functions are now exported:
-
- pi i Re Im arg
- log10 logn cbrt root
- tan cotan asin acos atan acotan
- sinh cosh tanh cotanh asinh acosh atanh acotanh
- cplx cplxe
-
-=head2 DB_File
+=head2 Required Updates
-There have been quite a few changes made to DB_File. Here are a few of
-the highlights:
-
-=over
-
-=item *
-
-Fixed a handful of bugs.
-
-=item *
-
-By public demand, added support for the standard hash function exists().
-
-=item *
-
-Made it compatible with Berkeley DB 1.86.
-
-=item *
-
-Made negative subscripts work with RECNO interface.
-
-=item *
-
-Changed the default flags from O_RDWR to O_CREAT|O_RDWR and the default
-mode from 0640 to 0666.
-
-=item *
-
-Made DB_File automatically import the open() constants (O_RDWR,
-O_CREAT etc.) from Fcntl, if available.
-
-=item *
-
-Updated documentation.
-
-=back
-
-Refer to the HISTORY section in DB_File.pm for a complete list of
-changes. Everything after DB_File 1.01 has been added since 5.003.
-
-=head2 Net::Ping
-
-Major rewrite - support added for both udp echo and real icmp pings.
-
-=head2 Overridden Built-ins
-
-Many of the Perl built-ins returning lists now have
-object-oriented overrides. These are:
-
- File::stat
- Net::hostent
- Net::netent
- Net::protoent
- Net::servent
- Time::gmtime
- Time::localtime
- User::grent
- User::pwent
-
-For example, you can now say
-
- use File::stat;
- use User::pwent;
- $his = (stat($filename)->st_uid == pwent($whoever)->pw_uid);
+ XXX Any???
=head1 Utility Changes
-=head2 xsubpp
-
-=over
-
-=item C<void> XSUBs now default to returning nothing
-
-Due to a documentation/implementation bug in previous versions of
-Perl, XSUBs with a return type of C<void> have actually been
-returning one value. Usually that value was the GV for the XSUB,
-but sometimes it was some already freed or reused value, which would
-sometimes lead to program failure.
-
-In Perl 5.004, if an XSUB is declared as returning C<void>, it
-actually returns no value, i.e. an empty list (though there is a
-backward-compatibility exception; see below). If your XSUB really
-does return an SV, you should give it a return type of C<SV *>.
-
-For backward compatibility, I<xsubpp> tries to guess whether a
-C<void> XSUB is really C<void> or if it wants to return an C<SV *>.
-It does so by examining the text of the XSUB: if I<xsubpp> finds
-what looks like an assignment to C<ST(0)>, it assumes that the
-XSUB's return type is really C<SV *>.
-
-=back
-
=head1 C Language API Changes
-=over
-
-=item C<gv_fetchmethod> and C<perl_call_sv>
-
-The C<gv_fetchmethod> function finds a method for an object, just like
-in Perl 5.003. The GV it returns may be a method cache entry.
-However, in Perl 5.004, method cache entries are not visible to users;
-therefore, they can no longer be passed directly to C<perl_call_sv>.
-Instead, you should use the C<GvCV> macro on the GV to extract its CV,
-and pass the CV to C<perl_call_sv>.
-
-The most likely symptom of passing the result of C<gv_fetchmethod> to
-C<perl_call_sv> is Perl's producing an "Undefined subroutine called"
-error on the I<second> call to a given method (since there is no cache
-on the first call).
-
-=back
-
=head1 Documentation Changes
-Many of the base and library pods were updated. These
-new pods are included in section 1:
-
-=over
-
-=item L<perldelta>
-
-This document.
-
-=item L<perllocale>
-
-Locale support (internationalization and localization).
-
-=item L<perltoot>
-
-Tutorial on Perl OO programming.
-
-=item L<perlapio>
-
-Perl internal IO abstraction interface.
-
-=item L<perldebug>
-
-Although not new, this has been massively updated.
-
-=item L<perlsec>
-
-Although not new, this has been massively updated.
-
-=back
-
-=head1 New Diagnostics
-
-Several new conditions will trigger warnings that were
-silent before. Some only affect certain platforms.
-The following new warnings and errors outline these.
-These messages are classified as follows (listed in
-increasing order of desperation):
-
- (W) A warning (optional).
- (D) A deprecation (optional).
- (S) A severe warning (mandatory).
- (F) A fatal error (trappable).
- (P) An internal error you should never see (trappable).
- (X) A very fatal error (non-trappable).
- (A) An alien error message (not generated by Perl).
-
-=over
-
-=item "my" variable %s masks earlier declaration in same scope
-
-(S) A lexical variable has been redeclared in the same scope, effectively
-eliminating all access to the previous instance. This is almost always
-a typographical error. Note that the earlier variable will still exist
-until the end of the scope or until all closure referents to it are
-destroyed.
-
-=item %s argument is not a HASH element or slice
-
-(F) The argument to delete() must be either a hash element, such as
-
- $foo{$bar}
- $ref->[12]->{"susie"}
-
-or a hash slice, such as
-
- @foo{$bar, $baz, $xyzzy}
- @{$ref->[12]}{"susie", "queue"}
-
-=item Allocation too large: %lx
-
-(X) You can't allocate more than 64K on an MSDOS machine.
-
-=item Allocation too large
-
-(F) You can't allocate more than 2^31+"small amount" bytes.
-
-=item Attempt to free non-existent shared string
-
-(P) Perl maintains a reference counted internal table of strings to
-optimize the storage and access of hash keys and other strings. This
-indicates someone tried to decrement the reference count of a string
-that can no longer be found in the table.
-
-=item Attempt to use reference as lvalue in substr
-
-(W) You supplied a reference as the first argument to substr() used
-as an lvalue, which is pretty strange. Perhaps you forgot to
-dereference it first. See L<perlfunc/substr>.
-
-=item Unsupported function fork
-
-(F) Your version of executable does not support forking.
-
-Note that under some systems, like OS/2, there may be different flavors of
-Perl executables, some of which may support fork, some not. Try changing
-the name you call Perl by to C<perl_>, C<perl__>, and so on.
-
-=item Ill-formed logical name |%s| in prime_env_iter
-
-(W) A warning peculiar to VMS. A logical name was encountered when preparing
-to iterate over %ENV which violates the syntactic rules governing logical
-names. Since it cannot be translated normally, it is skipped, and will not
-appear in %ENV. This may be a benign occurrence, as some software packages
-might directly modify logical name tables and introduce non-standard names,
-or it may indicate that a logical name table has been corrupted.
-
-=item Can't use bareword ("%s") as %s ref while "strict refs" in use
-
-(F) Only hard references are allowed by "strict refs". Symbolic references
-are disallowed. See L<perlref>.
-
-=item Constant subroutine %s redefined
-
-(S) You redefined a subroutine which had previously been eligible for
-inlining. See L<perlsub/"Constant Functions"> for commentary and
-workarounds.
-
-=item Died
-
-(F) You passed die() an empty string (the equivalent of C<die "">) or
-you called it with no args and both C<$@> and C<$_> were empty.
-
-=item Integer overflow in hex number
-
-(S) The literal hex number you have specified is too big for your
-architecture. On a 32-bit architecture the largest hex literal is
-0xFFFFFFFF.
-
-=item Integer overflow in octal number
-
-(S) The literal octal number you have specified is too big for your
-architecture. On a 32-bit architecture the largest octal literal is
-037777777777.
-
-=item Name "%s::%s" used only once: possible typo
-
-(W) Typographical errors often show up as unique variable names.
-If you had a good reason for having a unique name, then just mention
-it again somehow to suppress the message (the C<use vars> pragma is
-provided for just this purpose).
-
-=item Null picture in formline
-
-(F) The first argument to formline must be a valid format picture
-specification. It was found to be empty, which probably means you
-supplied it an uninitialized value. See L<perlform>.
-
-=item Offset outside string
-
-(F) You tried to do a read/write/send/recv operation with an offset
-pointing outside the buffer. This is difficult to imagine.
-The sole exception to this is that C<sysread()>ing past the buffer
-will extend the buffer and zero pad the new area.
-
-=item Stub found while resolving method `%s' overloading `%s' in package `%s'
-
-(P) Overloading resolution over @ISA tree may be broken by importing stubs.
-Stubs should never be implicitely created, but explicit calls to C<can>
-may break this.
-
-=item Cannot resolve method `%s' overloading `%s' in package `s'
-
-(P) Internal error trying to resolve overloading specified by a method
-name (as opposed to a subroutine reference).
-
-=item Out of memory!
-
-(X|F) The malloc() function returned 0, indicating there was insufficient
-remaining memory (or virtual memory) to satisfy the request.
-
-The request was judged to be small, so the possibility to trap it
-depends on the way Perl was compiled. By default it is not trappable.
-However, if compiled for this, Perl may use the contents of C<$^M> as
-an emergency pool after die()ing with this message. In this case the
-error is trappable I<once>.
-
-=item Out of memory during request for %s
-
-(F) The malloc() function returned 0, indicating there was insufficient
-remaining memory (or virtual memory) to satisfy the request. However,
-the request was judged large enough (compile-time default is 64K), so
-a possibility to shut down by trapping this error is granted.
-
-=item Possible attempt to put comments in qw() list
-
-(W) qw() lists contain items separated by whitespace; as with literal
-strings, comment characters are not ignored, but are instead treated
-as literal data. (You may have used different delimiters than the
-exclamation marks parentheses shown here; braces are also frequently
-used.)
-
-You probably wrote something like this:
-
- @list = qw(
- a # a comment
- b # another comment
- );
-
-when you should have written this:
-
- @list = qw(
- a
- b
- );
-
-If you really want comments, build your list the
-old-fashioned way, with quotes and commas:
-
- @list = (
- 'a', # a comment
- 'b', # another comment
- );
-
-=item Possible attempt to separate words with commas
-
-(W) qw() lists contain items separated by whitespace; therefore commas
-aren't needed to separate the items. (You may have used different
-delimiters than the parentheses shown here; braces are also frequently
-used.)
-
-You probably wrote something like this:
-
- qw! a, b, c !;
-
-which puts literal commas into some of the list items. Write it without
-commas if you don't want them to appear in your data:
-
- qw! a b c !;
-
-=item Scalar value @%s{%s} better written as $%s{%s}
-
-(W) You've used a hash slice (indicated by @) to select a single element of
-a hash. Generally it's better to ask for a scalar value (indicated by $).
-The difference is that C<$foo{&bar}> always behaves like a scalar, both when
-assigning to it and when evaluating its argument, while C<@foo{&bar}> behaves
-like a list when you assign to it, and provides a list context to its
-subscript, which can do weird things if you're expecting only one subscript.
-
-=item untie attempted while %d inner references still exist
-
-(W) A copy of the object returned from C<tie> (or C<tied>) was still
-valid when C<untie> was called.
-
-=item Value of %s construct can be "0"; test with defined()
-
-(W) In a conditional expression, you used <HANDLE>, <*> (glob), or
-C<readdir> as a boolean value. Each of these constructs can return a
-value of "0"; that would make the conditional expression false, which
-is probably not what you intended. When using these constructs in
-conditional expressions, test their values with the C<defined> operator.
-
-=item Variable "%s" may be unavailable
-
-(W) An inner (nested) I<anonymous> subroutine is inside a I<named>
-subroutine, and outside that is another subroutine; and the anonymous
-(innermost) subroutine is referencing a lexical variable defined in
-the outermost subroutine. For example:
-
- sub outermost { my $a; sub middle { sub { $a } } }
-
-If the anonymous subroutine is called or referenced (directly or
-indirectly) from the outermost subroutine, it will share the variable
-as you would expect. But if the anonymous subroutine is called or
-referenced when the outermost subroutine is not active, it will see
-the value of the shared variable as it was before and during the
-*first* call to the outermost subroutine, which is probably not what
-you want.
-
-In these circumstances, it is usually best to make the middle
-subroutine anonymous, using the C<sub {}> syntax. Perl has specific
-support for shared variables in nested anonymous subroutines; a named
-subroutine in between interferes with this feature.
-
-=item Variable "%s" will not stay shared
-
-(W) An inner (nested) I<named> subroutine is referencing a lexical
-variable defined in an outer subroutine.
-
-When the inner subroutine is called, it will probably see the value of
-the outer subroutine's variable as it was before and during the
-*first* call to the outer subroutine; in this case, after the first
-call to the outer subroutine is complete, the inner and outer
-subroutines will no longer share a common value for the variable. In
-other words, the variable will no longer be shared.
-
-Furthermore, if the outer subroutine is anonymous and references a
-lexical variable outside itself, then the outer and inner subroutines
-will I<never> share the given variable.
-
-This problem can usually be solved by making the inner subroutine
-anonymous, using the C<sub {}> syntax. When inner anonymous subs that
-reference variables in outer subroutines are called or referenced,
-they are automatically re-bound to the current values of such
-variables.
-
-=item Warning: something's wrong
-
-(W) You passed warn() an empty string (the equivalent of C<warn "">) or
-you called it with no args and C<$_> was empty.
-
-=item Got an error from DosAllocMem
-
-(P) An error peculiar to OS/2. Most probably you're using an obsolete
-version of Perl, and this should not happen anyway.
-
-=item Malformed PERLLIB_PREFIX
-
-(F) An error peculiar to OS/2. PERLLIB_PREFIX should be of the form
-
- prefix1;prefix2
-
-or
-
- prefix1 prefix2
-
-with non-empty prefix1 and prefix2. If C<prefix1> is indeed a prefix of
-a builtin library search path, prefix2 is substituted. The error may appear
-if components are not found, or are too long. See L<perlos2/"PERLLIB_PREFIX">.
-
-=item PERL_SH_DIR too long
-
-(F) An error peculiar to OS/2. PERL_SH_DIR is the directory to find the
-C<sh>-shell in. See L<perlos2/"PERL_SH_DIR">.
-
-=item Process terminated by SIG%s
-
-(W) This is a standard message issued by OS/2 applications, while *nix
-applications die in silence. It is considered a feature of the OS/2
-port. One can easily disable this by appropriate sighandlers, see
-L<perlipc/"Signals">. See L<perlos2/"Process terminated by SIGTERM/SIGINT">.
-
-=back
-
=head1 BUGS
If you find what you think is a bug, you might check the headers of
Home Page.
If you believe you have an unreported bug, please run the B<perlbug>
-program included with your release. Make sure you trim your bug
-down to a tiny but sufficient test case. Your bug report, along
-with the output of C<perl -V>, will be sent off to perlbug@perl.com
-to be analysed by the Perl porting team.
+program included with your release. Make sure you trim your bug down
+to a tiny but sufficient test case. Your bug report, along with the
+output of C<perl -V>, will be sent off to <F<perlbug@perl.com>> to be
+analysed by the Perl porting team.
=head1 SEE ALSO
The F<Changes> file for exhaustive details on what changed.
-The F<INSTALL> file for how to build Perl. This file has been
-significantly updated for 5.004, so even veteran users should
-look through it.
+The F<INSTALL> file for how to build Perl.
The F<README> file for general stuff.
-The F<Copying> file for copyright information.
+The F<Artistic> and F<Copying> files for copyright information.
=head1 HISTORY
-
-Constructed by Tom Christiansen, grabbing material with permission
-from innumerable contributors, with kibitzing by more than a few Perl
-porters.
-
-Last update: Tue Jan 14 14:03:02 EST 1997
projects / p5sagit/p5-mst-13.2.git / blobdiff