=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
+[XXX this needs more verbose summaries of the sub topics, instead of just
+the "See L<foo>." Scheduled for a second iteration. GSAR]
-Perl5.004 builds out of the box on Unix, Plan9, LynxOS, VMS, OS/2,
-QNX, and AmigaOS.
+=head1 About the new versioning system
-=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
+=head1 Incompatible Changes
-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 WARNING: This version is not binary compatible with Perl 5.004.
-=head2 Internal Change: FileHandle Deprecated
+Starting with Perl 5.004_50 there were many deep and far-reaching changes
+to the language internals. If you have dynamically loaded extensions
+that you built under perl 5.003 or 5.004, you can continue to use them
+with 5.004, but you will need to rebuild and reinstall those extensions
+to use them 5.005. See L<INSTALL> for detailed instructions on how to
+upgrade.
-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
+=head2 Default installation structure has changed
-=item $^E
+The new Configure defaults are designed to allow a smooth upgrade from
+5.004 to 5.005, but you should read L<INSTALL> for a detailed
+discussion of the changes in order to adapt them to your system.
-Extended error message on some platforms. (Also known as
-$EXTENDED_OS_ERROR if you C<use English>).
+=head2 Perl Source Compatibility
-=item $^H
+When none of the experimental features are enabled, there should be
+no user-visible Perl source compatibility issue.
-The current set of syntax checks enabled by C<use strict>. See the
-documentation of C<strict> for more details. Not actually new, but
-newly documented.
-Because it is intended for internal use by Perl core components,
-there is no C<use English> long name for this variable.
+If threads are enabled, then some caveats apply. C<@_> and C<$_> become
+lexical variables. The effect of this should be largely transparent to
+the user, but there are some boundary conditions under which user will
+need to be aware of the issues. [XXX Add e.g. here.]
-=item $^M
+Some new keywords have been introduced. These are generally expected to
+have very little impact on compatibility. See L</New C<INIT> keyword>,
+L</New C<lock> keyword>, and L</New C<qr//> operator>.
-By default, running out of memory it is not trappable. However, if
-compiled for this, Perl may use the contents of C<$^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 $SYSTEM_CHILD_STATUS if you C<use English>.)
-
-=back
-
-=head2 New and Changed Built-in Functions
-
-=over
+Certain barewords are now reserved. Use of these will provoke a warning
+if you have asked for them with the C<-w> switch.
+See L</C<our> is now a reserved word>.
-=item delete on slices
+=head2 C Source Compatibility
-This now works. (e.g. C<delete @ENV{'PATH', 'MANPATH'}>)
+=item Core sources now require ANSI C compiler
-=item flock
+=item Enabling threads has source compatibility issues
-is now supported on more platforms, and prefers fcntl
-to lockf when emulating.
+=head2 Binary Compatibility
-=item printf and sprintf
+This version is NOT binary compatible with older versions. All extensions
+will need to be recompiled.
-now support "%i" as a synonym for "%d", and the "h" modifier.
-So "%hi" means "short integer in decimal", and "%ho" means
-"unsigned short integer as octal".
+=head2 Security fixes may affect compatibility
-=item keys as an lvalue
+A few taint leaks and taint omissions have been corrected. This may lead
+to "failure" of scripts that used to work with older versions. Compiling
+with -DINCOMPLETE_TAINTS provides a perl with minimal amounts of changes
+to the tainting behavior. But note that the resulting perl will have
+known insecurities.
-As an lvalue, C<keys> allows you to increase the number of hash buckets
-allocated for the given associative array. This can gain you a measure
-of efficiency if you know the hash is going to get big. (This is
-similar to pre-extending an array by assigning a larger number to
-$#array.) If you say
+Oneliners with the C<-e> switch do not create temporary files anymore.
- keys %hash = 200;
+=head2 Relaxed new mandatory warnings introduced in 5.004
-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).
+Many new warnings that were introduced in 5.004 have been made
+optional. Some of these warnings are still present, but perl's new
+features make them less often a problem. See L<New Diagnostics>.
-=item my() in Control Structures
+=head2 Licensing
-You can now use my() (with or without the parentheses) in the control
-expressions of control structures such as:
+Perl has a new Social Contract for contributors. See F<Porting/Contract>.
- while (my $line = <>) {
- $line = lc $line;
- } continue {
- print $line;
- }
+The license included in much of the Perl documentation has changed.
+[XXX See where?]
- 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
+=head1 Core Changes
-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.
+=head2 Threads
-=item prototype(FUNCTION)
+WARNING: Threading is considered an experimental feature. Details of the
+implementation may change without notice. There are known limitations
+and and some bugs.
-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.)
+See L<README.threads>.
-=item $_ as Default
+=head2 Compiler
-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 @#
- $i
- .
- write;
- }
+WARNING: The Compiler and related tools are considered experimental.
+Features may change without notice, and there are known limitations
+and bugs.
-=back
+The Compiler produces three different types of transformations of a
+perl program. The C backend generates C code that captures perl's state
+just before execution begins. It eliminates the compile-time overheads
+of the regular perl interpreter, but the run-time performance remains
+comparatively the same. The CC backend generates optimized C code
+equivivalent to the code path at run-time. The CC backend has greater
+potential for big optimizations, but only a few optimizations are
+implemented currently. The Bytecode backend generates a platform
+independent bytecode representation of the interpreter's state
+just before execution. Thus, the Bytecode back end also eliminates
+much of the compilation overhead of the interpreter.
-=head2 New Built-in Methods
+The compiler comes with several valuable utilities.
-The C<UNIVERSAL> package automatically contains the following methods that
-are inherited by all other classes:
+C<B::Lint> is an experimental module to detect and warn about suspicious
+code, especially the cases that the C<-w> switch does not detect.
-=over
+C<B::Deparse> can be used to demystify perl code, and understand
+how perl optimizes certain constructs.
-=item isa(CLASS)
+C<B::Xref> generates cross reference reports of all definition and use
+of variables, subroutines and formats in a program.
-C<isa> returns I<true> if its object is blessed into a sub-class of C<CLASS>
+C<B::Showlex> show the lexical variables used by a subroutine or file
+at a glance.
-C<isa> is also exportable and can be called as a sub with two arguments. This
-allows the ability to check what a reference points to. Example:
+C<perlcc> is a simple frontend for compiling perl.
- use UNIVERSAL qw(isa);
+See C<ext/B/README>.
- if(isa($ref, 'ARRAY')) {
- ...
- }
+=head2 Regular Expressions
-=item can(METHOD)
+See L<perlre> and L<perlop>.
-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.
+=head2 Improved malloc()
-=item VERSION( [NEED] )
+See banner at the beginning of C<malloc.c> for details.
-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>.
+=head2 Quicksort is internally implemented
- use A 1.2 qw(some imported subs);
- # implies:
- A->VERSION(1.2);
+See C<perlfunc/sort>.
-=back
+=head2 Reliable signals
-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.
+Two kinds.
-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.
+Via C<Thread::Signal>.
-=head2 TIEHANDLE Now Supported
+Via switched runtime op loop. [XXX Not yet available.]
-See L<perltie> for other kinds of tie()s.
+=head2 Reliable stack pointers
-=over
+The internals now reallocate the perl stack only at predictable times.
+In particular, magic calls never trigger reallocations of the stack,
+because all reentrancy of the runtime is handled using a "stack of stacks".
+This should improve reliability of cached stack pointers in the internals
+and in XSUBs.
-=item TIEHANDLE classname, LIST
+=head2 Behavior of local() on composites is now well-defined
-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.
+See L<perlfunc/local>.
- sub TIEHANDLE {
- print "<shout>\n";
- my $i;
- return bless \$i, shift;
- }
+=head2 C<%!> is transparently tied to the L<Errno> module
-=item PRINT this, LIST
+See L<perlvar>, and L<Errno>.
-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.
+=head2 Pseudo-hashes are supported
- sub PRINT {
- $r = shift;
- $$r++;
- return print join( $, => map {uc} @_), $\;
- }
+See L<perlref>.
-=item READLINE this
+=head2 C<EXPR foreach EXPR> is supported
-This method will be called when the handle is read from. The method
-should return undef when there is no more data.
+See L<perlsyn>.
- sub READLINE {
- $r = shift;
- return "PRINT called $$r times\n";
- }
+=head2 Slice notation on glob elements is supported
-=item DESTROY this
+[XXX See what?]
-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.
+=head2 Keywords can be globally overridden
- sub DESTROY {
- print "</shout>\n";
- }
+See L<perlsub>.
-=back
-
-=item Efficiency Enhancements
+=head2 C<$^E> is meaningful on Win32
-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.
+See L<perlvar>.
-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 }>).
+=head2 C<foreach (1..1000000)> optimized
-=head1 Pragmata
+C<foreach (1..1000000)> is now optimized into a counting loop. It does
+not try to allocate a 1000000-size list anymore.
-Three new pragmatic modules exist:
+=head2 C<Foo::> can be used as implicitly quoted package name
-=over
+[XXX See what?]
-=item use blib
+=head2 C<exists $Foo::{Bar::}> tests existence of a package
-=item use blib 'dir'
+[XXX See what?]
-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.
+=head2 Better locale support
-Intended for use on command line with B<-M> option as a way of testing
-arbitrary scripts against an uninstalled version of a package.
+See L<perllocale>.
-=item use locale
+=head2 Experimental support for 64-bit platforms
-Tells the compiler to enable (or disable) the use of POSIX locales for
-built-in operations.
+Perl5 has always had 64-bit support on systems with 64-bit longs.
+Starting with 5.005, the beginnings of experimental support for systems
+with 32-bit long and 64-bit 'long long' integers has been added.
+If you add -DUSE_LONG_LONG to your ccflags in config.sh (or manually
+define it in perl.h) then perl will be built with 'long long' support.
+There will be many compiler warnings, and the resultant perl may not
+work on all systems. There are many other issues related to
+third-party extensions and libraries. This option exists to allow
+people to work on those issues.
-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.
+=head2 prototype() returns useful results on builtins
-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<perlfunc/prototype>.
-See L<perllocale> for more information.
+=head2 Re-blessing in DESTROY() supported for chaining DESTROY() methods
-=item use ops
+See L<perlobj/Destructors>.
-Disable unsafe opcodes, or any named opcodes, when compiling Perl code.
+=head2 All C<printf> format conversions are handled internally
-=back
+See L<perlfunc/printf>.
-=head1 Modules
+=head2 New C<INIT> keyword
-=head2 Installation Directories
+C<INIT> subs are like C<BEGIN> and C<END>, but they get run just before
+the perl runtime begins execution. e.g., the Perl Compiler makes use of
+C<INIT> blocks to initialize and resolve pointers to XSUBs.
-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.
+[XXX Needs to be documented in perlsub or perlmod.]
-=head2 Fcntl
+=head2 New C<lock> keyword
-New constants in the existing Fcntl modules are now supported,
-provided that your operating system happens to support them:
+The C<lock> keyword is the fundamental synchronization primitive
+in threaded perl. When threads are not enabled, it is currently a noop.
- F_GETOWN F_SETOWN
- O_ASYNC O_DEFER O_DSYNC O_FSYNC O_SYNC
- O_EXLOCK O_SHLOCK
+To minimize impact on source compatibility this keyword is "weak", i.e., any
+user-defined subroutine of the same name overrides it, unless a C<use Thread>
+has been seen.
-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().
+=head2 New C<qr//> operator
-In addition, the Fcntl module now provides these constants for use
-with the Perl operator flock():
+The C<qr//> operator, which is syntactically similar to the other quote-like
+operators, is used to create compiled regular expressions. This compiled
+form can now be explicitly passed around in variables, and interpolated in
+other regular expressions. See L<perlop> and L<perlre>.
- LOCK_SH LOCK_EX LOCK_NB LOCK_UN
+=head2 C<our> is now a reserved word
-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 Tied arrays are now fully supported
-=head2 Module Information Summary
+See L<Tie::Array>.
-Brand new modules, arranged by topic rather than strictly
-alphabetically:
+=head2 Tied handles support is better
- CPAN interface to Comprehensive Perl Archive Network
- CPAN::FirstTime create a CPAN configuration file
- CPAN::Nox run CPAN while avoiding compiled extensions
+Several missing hooks have been added. There is also a new base class for
+TIEARRAY implementations. See L<Tie::Array>.
- 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
+=head1 Supported Platforms
- ExtUtils/Embed.pm Utilities for embedding Perl in C programs
- ExtUtils/testlib.pm Fixes up @INC to use just-built extension
+Configure has many incremental improvements. Site-wide policy for building
+perl can now be made persistent, via Policy.sh. Configure also records
+the command-line arguments used in F<config.sh>.
- Fatal.pm Make do-or-die equivalents of functions
- FindBin.pm Find path of currently executing program
+=head2 New Platforms
- 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*
+BeOS is now supported. See L<README.beos>.
- Tie/RefHash.pm Base class for tied hashes with references as keys
+DOS is now supported under the DJGPP tools. See L<README.dos>.
- UNIVERSAL.pm Base class for *ALL* classes
+=head2 Changes in existing support
-=head2 IO
+Win32 support has been vastly enhanced. Support for Perl Object, a C++
+encapsulation of Perl. GCC and EGCS are now supported on Win32.
+[XXX Perl Object needs a big explanation elsewhere, and a pointer to
+that location here.]
-The IO module provides a simple mechanism to load all of the IO modules at one
-go. Currently this includes:
+VMS configuration system has been rewritten. See L<README.vms>.
- IO::Handle
- IO::Seekable
- IO::File
- IO::Pipe
- IO::Socket
+OpenBSD better supported. [XXX what others?]
-For more information on any of these modules, please see its
-respective documentation.
+=head1 Modules and Pragmata
-=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
-
-There have been quite a few changes made to DB_File. Here are a few of
-the highlights:
+=head2 New Modules
=over
-=item *
+=item B
-Fixed a handful of bugs.
+Perl compiler and tools. See [XXX what?].
-=item *
+=item Data::Dumper
-By public demand, added support for the standard hash function exists().
+A module to pretty print Perl data. See L<Data::Dumper>.
-=item *
+=item Errno
-Made it compatible with Berkeley DB 1.86.
+A module to look up errors more conveniently. See L<Errno>.
-=item *
+=item File::Spec
-Made negative subscripts work with RECNO interface.
+A portable API for file operations.
-=item *
+=item ExtUtils::Installed
-Changed the default flags from O_RDWR to O_CREAT|O_RDWR and the default
-mode from 0640 to 0666.
+Query and manage installed modules.
-=item *
+=item ExtUtils::Packlist
-Made DB_File automatically import the open() constants (O_RDWR,
-O_CREAT etc.) from Fcntl, if available.
+Manipulate .packlist files.
-=item *
+=item Fatal
-Updated documentation.
+Make functions/builtins succeed or die.
-=back
+=item IPC::SysV
-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.
+Constants and other support infrastructure for System V IPC operations
+in perl.
-=head2 Net::Ping
+=item Test
-Major rewrite - support added for both udp echo and real icmp pings.
+A framework for writing testsuites.
-=head2 Overridden Built-ins
+=item Tie::Array
-Many of the Perl built-ins returning lists now have
-object-oriented overrides. These are:
+Base class for tied arrays.
- File::stat
- Net::hostent
- Net::netent
- Net::protoent
- Net::servent
- Time::gmtime
- Time::localtime
- User::grent
- User::pwent
+=item Tie::Handle
-For example, you can now say
+Base class for tied handles.
- use File::stat;
- use User::pwent;
- $his = (stat($filename)->st_uid == pwent($whoever)->pw_uid);
+=item Thread
-=head1 Utility Changes
+Perl thread creation, manipulation, and support.
-=head2 xsubpp
+=item attrs
-=over
+Set subroutine attributes.
-=item C<void> XSUBs now default to returning nothing
+=item fields
-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.
+Compile-time class fields.
-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 *>.
+=item re
-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 *>.
+Various pragmata to control behavior of regular expressions.
=back
-=head1 C Language API Changes
+=head2 Changes in existing modules
=over
-=item C<gv_fetchmethod> and C<perl_call_sv>
+=item CGI
-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>.
+CGI has been updated to version 2.42.
-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).
+=item POSIX
-=back
-
-=head1 Documentation Changes
+POSIX now has its own platform-specific hints files.
-Many of the base and library pods were updated. These
-new pods are included in section 1:
-
-=over
+=item DB_File
-=item L<perldelta>
+DB_File supports version 2.x of Berkeley DB. See C<ext/DB_File/Changes>.
-This document.
+=item MakeMaker
-=item L<perllocale>
+MakeMaker now supports writing empty makefiles, provides a way to
+specify that site umask() policy should be honored. There is also
+better support for manipulation of .packlist files, and getting
+information about installed modules.
-Locale support (internationalization and localization).
+Extensions that have both architecture-dependent and
+architecture-independent files are now always installed completely in
+the architecture-dependent locations. Previously, the shareable parts
+were shared both across architectures and across perl versions and were
+therefore liable to be overwritten with newer versions that might have
+subtle incompatibilities.
-=item L<perltoot>
+=item CPAN
-Tutorial on Perl OO programming.
+[XXX What?]
-=item L<perlapio>
+=item Cwd
-Perl internal IO abstraction interface.
+Cwd::cwd is faster on most platforms.
-=item L<perldebug>
+=item Benchmark
-Although not new, this has been massively updated.
-
-=item L<perlsec>
-
-Although not new, this has been massively updated.
+Keeps better time.
=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
+=head1 Utility Changes
-(X) You can't allocate more than 64K on an MSDOS machine.
+h2ph and related utilities have been vastly overhauled.
-=item Allocation too large
+perlcc, a new experimental front end for the compiler is available.
-(F) You can't allocate more than 2^31+"small amount" bytes.
+The crude GNU configure emulator is now called configure.gnu.
-=item Attempt to free non-existent shared string
+=head1 API Changes
-(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.
+=head2 Incompatible Changes
-=item Attempt to use reference as lvalue in substr
+=head2 Deprecations, Extensions
-(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>.
+=head2 C++ Support
-=item Unsupported function fork
+=head1 Documentation Changes
-(F) Your version of executable does not support forking.
+Config.pm now has a glossary of variables.
-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.
+Porting/patching.pod has detailed instructions on how to create and
+submit patches for perl.
-=item Ill-formed logical name |%s| in prime_env_iter
+=head1 New Diagnostics
-(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.
+=over
-=item Can't use bareword ("%s") as %s ref while "strict refs" in use
+=item Ambiguous call resolved as CORE::%s(), qualify as such or use &
-(F) Only hard references are allowed by "strict refs". Symbolic references
-are disallowed. See L<perlref>.
+(W) A subroutine you have declared has the same name as a Perl keyword,
+and you have used the name without qualification for calling one or the
+other. Perl decided to call the builtin because the subroutine is
+not imported.
-=item Constant subroutine %s redefined
+To force interpretation as a subroutine call, either put an ampersand
+before the subroutine name, or qualify the name with its package.
+Alternatively, you can import the subroutine (or pretend that it's
+imported with the C<use subs> pragma).
-(S) You redefined a subroutine which had previously been eligible for
-inlining. See L<perlsub/"Constant Functions"> for commentary and
-workarounds.
+To silently interpret it as the Perl operator, use the C<CORE::> prefix
+on the operator (e.g. C<CORE::log($x)>) or by declaring the subroutine
+to be an object method (see L<attrs>).
-=item Died
+=item Bad index while coercing array into hash
-(F) You passed die() an empty string (the equivalent of C<die "">) or
-you called it with no args and both C<$@> and C<$_> were empty.
+(F) The index looked up in the hash found as the 0'th element of a
+pseudo-hash is not legal. Index values must be at 1 or greater.
+See L<perlref>.
-=item Integer overflow in hex number
+=item Bareword "%s" refers to nonexistent package
-(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.
+(W) You used a qualified bareword of the form C<Foo::>, but
+the compiler saw no other uses of that namespace before that point.
+Perhaps you need to predeclare a package?
-=item Integer overflow in octal number
+=item Can't call method "%s" on an undefined value
-(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.
+(F) You used the syntax of a method call, but the slot filled by the
+object reference or package name contains an undefined value.
+Something like this will reproduce the error:
-=item Name "%s::%s" used only once: possible typo
+ $BADREF = 42;
+ process $BADREF 1,2,3;
+ $BADREF->process(1,2,3);
-(W) Typographical errors often show up as unique variable names.
-If you had a good reason for having a unique name, then just mention
-it again somehow to suppress the message (the C<use vars> pragma is
-provided for just this purpose).
+=item Can't coerce array into hash
-=item Null picture in formline
+(F) You used an array where a hash was expected, but the array has no
+information on how to map from keys to array indices. You can do that
+only with arrays that have a hash reference at index 0.
-(F) The first argument to formline must be a valid format picture
-specification. It was found to be empty, which probably means you
-supplied it an uninitialized value. See L<perlform>.
+=item Can't goto subroutine from an eval-string
-=item Offset outside string
+(F) The "goto subroutine" call can't be used to jump out of an eval "string".
+(You can use it to jump out of an eval {BLOCK}, but you probably don't want to.)
-(F) You tried to do a read/write/send/recv operation with an offset
-pointing outside the buffer. This is difficult to imagine.
-The sole exception to this is that C<sysread()>ing past the buffer
-will extend the buffer and zero pad the new area.
+=item Can't use %%! because Errno.pm is not available
-=item Stub found while resolving method `%s' overloading `%s' in package `%s'
+(F) The first time the %! hash is used, perl automatically loads the
+Errno.pm module. The Errno module is expected to tie the %! hash to
+provide symbolic names for C<$!> errno values.
-(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 Can't use %%! because Errno.pm is not available
-=item Cannot resolve method `%s' overloading `%s' in package `s'
+(F) The first time the %! hash is used, perl automatically loads the
+Errno.pm module. The Errno module is expected to tie the %! hash to
+provide symbolic names for C<$!> errno values.
-(P) Internal error trying to resolve overloading specified by a method
-name (as opposed to a subroutine reference).
+=item Cannot find an opnumber for "%s"
-=item Out of memory!
+(F) A string of a form C<CORE::word> was given to prototype(), but
+there is no builtin with the name C<word>.
-(X|F) The malloc() function returned 0, indicating there was insufficient
-remaining memory (or virtual memory) to satisfy the request.
+=item Character class syntax [. .] is reserved for future extensions
-The request was judged to be small, so the possibility to trap it
-depends on the way Perl was compiled. By default it is not trappable.
-However, if compiled for this, Perl may use the contents of C<$^M> as
-an emergency pool after die()ing with this message. In this case the
-error is trappable I<once>.
+(W) Within regular expression character classes ([]) the syntax beginning
+with "[." and ending with ".]" is reserved for future extensions.
+If you need to represent those character sequences inside a regular
+expression character class, just quote the square brackets with the
+backslash: "\[." and ".\]".
-=item Out of memory during request for %s
+=item Character class syntax [: :] is reserved for future extensions
-(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.
+(W) Within regular expression character classes ([]) the syntax beginning
+with "[:" and ending with ":]" is reserved for future extensions.
+If you need to represent those character sequences inside a regular
+expression character class, just quote the square brackets with the
+backslash: "\[:" and ":\]".
-=item Possible attempt to put comments in qw() list
+=item Character class syntax [= =] is reserved for future extensions
-(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.)
+(W) Within regular expression character classes ([]) the syntax
+beginning with "[=" and ending with "=]" is reserved for future extensions.
+If you need to represent those character sequences inside a regular
+expression character class, just quote the square brackets with the
+backslash: "\[=" and "=\]".
-You probably wrote something like this:
+=item %s: Eval-group in insecure regular expression
- @list = qw(
- a # a comment
- b # another comment
- );
+(F) Perl detected tainted data when trying to compile a regular expression
+that contains the C<(?{ ... })> zero-width assertion, which is unsafe.
+See L<perlre/(?{ code })>, and L<perlsec>.
-when you should have written this:
+=item %s: Eval-group not allowed, use re 'eval'
- @list = qw(
- a
- b
- );
+(F) A regular expression contained the C<(?{ ... })> zero-width assertion,
+but that construct is only allowed when the C<use re 'eval'> pragma is
+in effect. See L<perlre/(?{ code })>.
-If you really want comments, build your list the
-old-fashioned way, with quotes and commas:
+=item %s: Eval-group not allowed at run time
- @list = (
- 'a', # a comment
- 'b', # another comment
- );
+(F) Perl tried to compile a regular expression containing the C<(?{ ... })>
+zero-width assertion at run time, as it would when the pattern contains
+interpolated values. Since that is a security risk, it is not allowed.
+If you insist, you may still do this by explicitly building the pattern
+from an interpolated string at run time and using that in an eval().
+See L<perlre/(?{ code })>.
-=item Possible attempt to separate words with commas
+=item Explicit blessing to '' (assuming package main)
-(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.)
+(W) You are blessing a reference to a zero length string. This has
+the effect of blessing the reference into the package main. This is
+usually not what you want. Consider providing a default target
+package, e.g. bless($ref, $p or 'MyPackage');
-You probably wrote something like this:
+=item Illegal hex digit ignored
- qw! a, b, c !;
+(W) You may have tried to use a character other than 0 - 9 or A - F in a
+hexadecimal number. Interpretation of the hexadecimal number stopped
+before the illegal character.
-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:
+=item No such array field
- qw! a b c !;
+(F) You tried to access an array as a hash, but the field name used is
+not defined. The hash at index 0 should map all valid field names to
+array indices for that to work.
-=item Scalar value @%s{%s} better written as $%s{%s}
+=item No such field "%s" in variable %s of type %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.
+(F) You tried to access a field of a typed variable where the type
+does not know about the field name. The field names are looked up in
+the %FIELDS hash in the type package at compile time. The %FIELDS hash
+is usually set up with the 'fields' pragma.
-=item untie attempted while %d inner references still exist
+=item Out of memory during ridiculously large request
-(W) A copy of the object returned from C<tie> (or C<tied>) was still
-valid when C<untie> was called.
+(F) You can't allocate more than 2^31+"small amount" bytes. This error
+is most likely to be caused by a typo in the Perl program. e.g., C<$arr[time]>
+instead of C<$arr[$time]>.
-=item Value of %s construct can be "0"; test with defined()
+=item Range iterator outside integer range
-(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.
+(F) One (or both) of the numeric arguments to the range operator ".."
+are outside the range which can be represented by integers internally.
+One possible workaround is to force Perl to use magical string
+increment by prepending "0" to your numbers.
-=item Variable "%s" may be unavailable
+=item Recursive inheritance detected while looking for method '%s' in package '%s'
-(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:
+(F) More than 100 levels of inheritance were encountered while invoking a
+method. Probably indicates an unintended loop in your inheritance hierarchy.
- sub outermost { my $a; sub middle { sub { $a } } }
+=item Reference found where even-sized list expected
-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.
+(W) You gave a single reference where Perl was expecting a list with
+an even number of elements (for assignment to a hash). This
+usually means that you used the anon hash constructor when you meant
+to use parens. In any case, a hash requires key/value B<pairs>.
-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.
+ %hash = { one => 1, two => 2, }; # WRONG
+ %hash = [ qw/ an anon array / ]; # WRONG
+ %hash = ( one => 1, two => 2, ); # right
+ %hash = qw( one 1 two 2 ); # also fine
-=item Variable "%s" will not stay shared
+=item Undefined value assigned to typeglob
-(W) An inner (nested) I<named> subroutine is referencing a lexical
-variable defined in an outer subroutine.
+(W) An undefined value was assigned to a typeglob, a la C<*foo = undef>.
+This does nothing. It's possible that you really mean C<undef *foo>.
-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.
+=item Use of reserved word "%s" is deprecated
-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.
+(D) The indicated bareword is a reserved word. Future versions of perl
+may use it as a keyword, so you're better off either explicitly quoting
+the word in a manner appropriate for its context of use, or using a
+different name altogether. The warning can be suppressed for subroutine
+names by either adding a C<&> prefix, or using a package qualifier,
+e.g. C<&our()>, or C<Foo::our()>.
-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 perl: warning: Setting locale failed.
-=item Warning: something's wrong
+(S) The whole warning message will look something like:
-(W) You passed warn() an empty string (the equivalent of C<warn "">) or
-you called it with no args and C<$_> was empty.
+ perl: warning: Setting locale failed.
+ perl: warning: Please check that your locale settings:
+ LC_ALL = "En_US",
+ LANG = (unset)
+ are supported and installed on your system.
+ perl: warning: Falling back to the standard locale ("C").
-=item Got an error from DosAllocMem
+Exactly what were the failed locale settings varies. In the above the
+settings were that the LC_ALL was "En_US" and the LANG had no value.
+This error means that Perl detected that you and/or your system
+administrator have set up the so-called variable system but Perl could
+not use those settings. This was not dead serious, fortunately: there
+is a "default locale" called "C" that Perl can and will use, the
+script will be run. Before you really fix the problem, however, you
+will get the same error message each time you run Perl. How to really
+fix the problem can be found in L<perllocale> section B<LOCALE PROBLEMS>.
-(P) An error peculiar to OS/2. Most probably you're using an obsolete
-version of Perl, and this should not happen anyway.
+=back
-=item Malformed PERLLIB_PREFIX
-(F) An error peculiar to OS/2. PERLLIB_PREFIX should be of the form
+=head1 Obsolete Diagnostics
- prefix1;prefix2
+=over
-or
+=item Can't mktemp()
- prefix1 prefix2
+(F) The mktemp() routine failed for some reason while trying to process
+a B<-e> switch. Maybe your /tmp partition is full, or clobbered.
-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 Can't write to temp file for B<-e>: %s
-=item PERL_SH_DIR too long
+(F) The write routine failed for some reason while trying to process
+a B<-e> switch. Maybe your /tmp partition is full, or clobbered.
-(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 Cannot open temporary file
-=item Process terminated by SIG%s
+(F) The create routine failed for some reason while trying to process
+a B<-e> switch. Maybe your /tmp partition is full, or clobbered.
-(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
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
+=cut
https://perl5.git.perl.org / perl5.git / blobdiff