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diff --git a/contrib/perl5/pod/perldelta.pod b/contrib/perl5/pod/perldelta.pod deleted file mode 100644 index 86235f0..0000000 --- a/contrib/perl5/pod/perldelta.pod +++ /dev/null @@ -1,3646 +0,0 @@ -=head1 NAME - -perldelta - what's new for perl v5.6.x - -=head1 DESCRIPTION - -This document describes differences between the 5.005 release and the 5.6.1 -release. - -=head1 Summary of changes between 5.6.0 and 5.6.1 - -This section contains a summary of the changes between the 5.6.0 release -and the 5.6.1 release. More details about the changes mentioned here -may be found in the F<Changes> files that accompany the Perl source -distribution. See L<perlhack> for pointers to online resources where you -can inspect the individual patches described by these changes. - -=head2 Security Issues - -suidperl will not run /bin/mail anymore, because some platforms have -a /bin/mail that is vulnerable to buffer overflow attacks. - -Note that suidperl is neither built nor installed by default in -any recent version of perl. Use of suidperl is highly discouraged. -If you think you need it, try alternatives such as sudo first. -See http://www.courtesan.com/sudo/. - -=head2 Core bug fixes - -This is not an exhaustive list. It is intended to cover only the -significant user-visible changes. - -=over - -=item C<UNIVERSAL::isa()> - -A bug in the caching mechanism used by C<UNIVERSAL::isa()> that affected -base.pm has been fixed. The bug has existed since the 5.005 releases, -but wasn't tickled by base.pm in those releases. - -=item Memory leaks - -Various cases of memory leaks and attempts to access uninitialized memory -have been cured. See L</"Known Problems"> below for further issues. - -=item Numeric conversions - -Numeric conversions did not recognize changes in the string value -properly in certain circumstances. - -In other situations, large unsigned numbers (those above 2**31) could -sometimes lose their unsignedness, causing bogus results in arithmetic -operations. - -Integer modulus on large unsigned integers sometimes returned -incorrect values. - -Perl 5.6.0 generated "not a number" warnings on certain conversions where -previous versions didn't. - -These problems have all been rectified. - -Infinity is now recognized as a number. - -=item qw(a\\b) - -In Perl 5.6.0, qw(a\\b) produced a string with two backslashes instead -of one, in a departure from the behavior in previous versions. The -older behavior has been reinstated. - -=item caller() - -caller() could cause core dumps in certain situations. Carp was sometimes -affected by this problem. - -=item Bugs in regular expressions - -Pattern matches on overloaded values are now handled correctly. - -Perl 5.6.0 parsed m/\x{ab}/ incorrectly, leading to spurious warnings. -This has been corrected. - -The RE engine found in Perl 5.6.0 accidentally pessimised certain kinds -of simple pattern matches. These are now handled better. - -Regular expression debug output (whether through C<use re 'debug'> -or via C<-Dr>) now looks better. - -Multi-line matches like C<"a\nxb\n" =~ /(?!\A)x/m> were flawed. The -bug has been fixed. - -Use of $& could trigger a core dump under some situations. This -is now avoided. - -Match variables $1 et al., weren't being unset when a pattern match -was backtracking, and the anomaly showed up inside C</...(?{ ... }).../> -etc. These variables are now tracked correctly. - -pos() did not return the correct value within s///ge in earlier -versions. This is now handled correctly. - -=item "slurp" mode - -readline() on files opened in "slurp" mode could return an extra "" at -the end in certain situations. This has been corrected. - -=item Autovivification of symbolic references to special variables - -Autovivification of symbolic references of special variables described -in L<perlvar> (as in C<${$num}>) was accidentally disabled. This works -again now. - -=item Lexical warnings - -Lexical warnings now propagate correctly into C<eval "...">. - -C<use warnings qw(FATAL all)> did not work as intended. This has been -corrected. - -Lexical warnings could leak into other scopes in some situations. -This is now fixed. - -warnings::enabled() now reports the state of $^W correctly if the caller -isn't using lexical warnings. - -=item Spurious warnings and errors - -Perl 5.6.0 could emit spurious warnings about redefinition of dl_error() -when statically building extensions into perl. This has been corrected. - -"our" variables could result in bogus "Variable will not stay shared" -warnings. This is now fixed. - -"our" variables of the same name declared in two sibling blocks -resulted in bogus warnings about "redeclaration" of the variables. -The problem has been corrected. - -=item glob() - -Compatibility of the builtin glob() with old csh-based glob has been -improved with the addition of GLOB_ALPHASORT option. See C<File::Glob>. - -File::Glob::glob() has been renamed to File::Glob::bsd_glob() -because the name clashes with the builtin glob(). The older -name is still available for compatibility, but is deprecated. - -Spurious syntax errors generated in certain situations, when glob() -caused File::Glob to be loaded for the first time, have been fixed. - -=item Tainting - -Some cases of inconsistent taint propagation (such as within hash -values) have been fixed. - -The tainting behavior of sprintf() has been rationalized. It does -not taint the result of floating point formats anymore, making the -behavior consistent with that of string interpolation. - -=item sort() - -Arguments to sort() weren't being provided the right wantarray() context. -The comparison block is now run in scalar context, and the arguments to -be sorted are always provided list context. - -sort() is also fully reentrant, in the sense that the sort function -can itself call sort(). This did not work reliably in previous releases. - -=item #line directives - -#line directives now work correctly when they appear at the very -beginning of C<eval "...">. - -=item Subroutine prototypes - -The (\&) prototype now works properly. - -=item map() - -map() could get pathologically slow when the result list it generates -is larger than the source list. The performance has been improved for -common scenarios. - -=item Debugger - -Debugger exit code now reflects the script exit code. - -Condition C<"0"> in breakpoints is now treated correctly. - -The C<d> command now checks the line number. - -C<$.> is no longer corrupted by the debugger. - -All debugger output now correctly goes to the socket if RemotePort -is set. - -=item PERL5OPT - -PERL5OPT can be set to more than one switch group. Previously, -it used to be limited to one group of options only. - -=item chop() - -chop(@list) in list context returned the characters chopped in reverse -order. This has been reversed to be in the right order. - -=item Unicode support - -Unicode support has seen a large number of incremental improvements, -but continues to be highly experimental. It is not expected to be -fully supported in the 5.6.x maintenance releases. - -substr(), join(), repeat(), reverse(), quotemeta() and string -concatenation were all handling Unicode strings incorrectly in -Perl 5.6.0. This has been corrected. - -Support for C<tr///CU> and C<tr///UC> etc., have been removed since -we realized the interface is broken. For similar functionality, -see L<perlfunc/pack>. - -The Unicode Character Database has been updated to version 3.0.1 -with additions made available to the public as of August 30, 2000. - -The Unicode character classes \p{Blank} and \p{SpacePerl} have been -added. "Blank" is like C isblank(), that is, it contains only -"horizontal whitespace" (the space character is, the newline isn't), -and the "SpacePerl" is the Unicode equivalent of C<\s> (\p{Space} -isn't, since that includes the vertical tabulator character, whereas -C<\s> doesn't.) - -If you are experimenting with Unicode support in perl, the development -versions of Perl may have more to offer. In particular, I/O layers -are now available in the development track, but not in the maintenance -track, primarily to do backward compatibility issues. Unicode support -is also evolving rapidly on a daily basis in the development track--the -maintenance track only reflects the most conservative of these changes. - -=item 64-bit support - -Support for 64-bit platforms has been improved, but continues to be -experimental. The level of support varies greatly among platforms. - -=item Compiler - -The B Compiler and its various backends have had many incremental -improvements, but they continue to remain highly experimental. Use in -production environments is discouraged. - -The perlcc tool has been rewritten so that the user interface is much -more like that of a C compiler. - -The perlbc tools has been removed. Use C<perlcc -B> instead. - -=item Lvalue subroutines - -There have been various bugfixes to support lvalue subroutines better. -However, the feature still remains experimental. - -=item IO::Socket - -IO::Socket::INET failed to open the specified port if the service -name was not known. It now correctly uses the supplied port number -as is. - -=item File::Find - -File::Find now chdir()s correctly when chasing symbolic links. - -=item xsubpp - -xsubpp now tolerates embedded POD sections. - -=item C<no Module;> - -C<no Module;> does not produce an error even if Module does not have an -unimport() method. This parallels the behavior of C<use> vis-a-vis -C<import>. - -=item Tests - -A large number of tests have been added. - -=back - -=head2 Core features - -untie() will now call an UNTIE() hook if it exists. See L<perltie> -for details. - -The C<-DT> command line switch outputs copious tokenizing information. -See L<perlrun>. - -Arrays are now always interpolated in double-quotish strings. Previously, -C<"foo@bar.com"> used to be a fatal error at compile time, if an array -C<@bar> was not used or declared. This transitional behavior was -intended to help migrate perl4 code, and is deemed to be no longer useful. -See L</"Arrays now always interpolate into double-quoted strings">. - -keys(), each(), pop(), push(), shift(), splice() and unshift() -can all be overridden now. - -C<my __PACKAGE__ $obj> now does the expected thing. - -=head2 Configuration issues - -On some systems (IRIX and Solaris among them) the system malloc is demonstrably -better. While the defaults haven't been changed in order to retain binary -compatibility with earlier releases, you may be better off building perl -with C<Configure -Uusemymalloc ...> as discussed in the F<INSTALL> file. - -C<Configure> has been enhanced in various ways: - -=over - -=item * - -Minimizes use of temporary files. - -=item * - -By default, does not link perl with libraries not used by it, such as -the various dbm libraries. SunOS 4.x hints preserve behavior on that -platform. - -=item * - -Support for pdp11-style memory models has been removed due to obsolescence. - -=item * - -Building outside the source tree is supported on systems that have -symbolic links. This is done by running - - sh /path/to/source/Configure -Dmksymlinks ... - make all test install - -in a directory other than the perl source directory. See F<INSTALL>. - -=item * - -C<Configure -S> can be run non-interactively. - -=back - -=head2 Documentation - -README.aix, README.solaris and README.macos have been added. README.posix-bc -has been renamed to README.bs2000. These are installed as L<perlaix>, -L<perlsolaris>, L<perlmacos>, and L<perlbs2000> respectively. - -The following pod documents are brand new: - - perlclib Internal replacements for standard C library functions - perldebtut Perl debugging tutorial - perlebcdic Considerations for running Perl on EBCDIC platforms - perlnewmod Perl modules: preparing a new module for distribution - perlrequick Perl regular expressions quick start - perlretut Perl regular expressions tutorial - perlutil utilities packaged with the Perl distribution - -The F<INSTALL> file has been expanded to cover various issues, such as -64-bit support. - -A longer list of contributors has been added to the source distribution. -See the file C<AUTHORS>. - -Numerous other changes have been made to the included documentation and FAQs. - -=head2 Bundled modules - -The following modules have been added. - -=over - -=item B::Concise - -Walks Perl syntax tree, printing concise info about ops. See L<B::Concise>. - -=item File::Temp - -Returns name and handle of a temporary file safely. See L<File::Temp>. - -=item Pod::LaTeX - -Converts Pod data to formatted LaTeX. See L<Pod::LaTeX>. - -=item Pod::Text::Overstrike - -Converts POD data to formatted overstrike text. See L<Pod::Text::Overstrike>. - -=back - -The following modules have been upgraded. - -=over - -=item CGI - -CGI v2.752 is now included. - -=item CPAN - -CPAN v1.59_54 is now included. - -=item Class::Struct - -Various bugfixes have been added. - -=item DB_File - -DB_File v1.75 supports newer Berkeley DB versions, among other -improvements. - -=item Devel::Peek - -Devel::Peek has been enhanced to support dumping of memory statistics, -when perl is built with the included malloc(). - -=item File::Find - -File::Find now supports pre and post-processing of the files in order -to sort() them, etc. - -=item Getopt::Long - -Getopt::Long v2.25 is included. - -=item IO::Poll - -Various bug fixes have been included. - -=item IPC::Open3 - -IPC::Open3 allows use of numeric file descriptors. - -=item Math::BigFloat - -The fmod() function supports modulus operations. Various bug fixes -have also been included. - -=item Math::Complex - -Math::Complex handles inf, NaN etc., better. - -=item Net::Ping - -ping() could fail on odd number of data bytes, and when the echo service -isn't running. This has been corrected. - -=item Opcode - -A memory leak has been fixed. - -=item Pod::Parser - -Version 1.13 of the Pod::Parser suite is included. - -=item Pod::Text - -Pod::Text and related modules have been upgraded to the versions -in podlators suite v2.08. - -=item SDBM_File - -On dosish platforms, some keys went missing because of lack of support for -files with "holes". A workaround for the problem has been added. - -=item Sys::Syslog - -Various bug fixes have been included. - -=item Tie::RefHash - -Now supports Tie::RefHash::Nestable to automagically tie hashref values. - -=item Tie::SubstrHash - -Various bug fixes have been included. - -=back - -=head2 Platform-specific improvements - -The following new ports are now available. - -=over - -=item NCR MP-RAS - -=item NonStop-UX - -=back - -Perl now builds under Amdahl UTS. - -Perl has also been verified to build under Amiga OS. - -Support for EPOC has been much improved. See README.epoc. - -Building perl with -Duseithreads or -Duse5005threads now works -under HP-UX 10.20 (previously it only worked under 10.30 or later). -You will need a thread library package installed. See README.hpux. - -Long doubles should now work under Linux. - -MacOS Classic is now supported in the mainstream source package. -See README.macos. - -Support for MPE/iX has been updated. See README.mpeix. - -Support for OS/2 has been improved. See C<os2/Changes> and README.os2. - -Dynamic loading on z/OS (formerly OS/390) has been improved. See -README.os390. - -Support for VMS has seen many incremental improvements, including -better support for operators like backticks and system(), and better -%ENV handling. See C<README.vms> and L<perlvms>. - -Support for Stratus VOS has been improved. See C<vos/Changes> and README.vos. - -Support for Windows has been improved. - -=over - -=item * - -fork() emulation has been improved in various ways, but still continues -to be experimental. See L<perlfork> for known bugs and caveats. - -=item * - -%SIG has been enabled under USE_ITHREADS, but its use is completely -unsupported under all configurations. - -=item * - -Borland C++ v5.5 is now a supported compiler that can build Perl. -However, the generated binaries continue to be incompatible with those -generated by the other supported compilers (GCC and Visual C++). - -=item * - -Non-blocking waits for child processes (or pseudo-processes) are -supported via C<waitpid($pid, &POSIX::WNOHANG)>. - -=item * - -A memory leak in accept() has been fixed. - -=item * - -wait(), waitpid() and backticks now return the correct exit status under -Windows 9x. - -=item * - -Trailing new %ENV entries weren't propagated to child processes. This -is now fixed. - -=item * - -Current directory entries in %ENV are now correctly propagated to child -processes. - -=item * - -Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x. - -=item * - -The makefiles now provide a single switch to bulk-enable all the features -enabled in ActiveState ActivePerl (a popular binary distribution). - -=item * - -Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root. -Other bugs in chdir() and Cwd::cwd() have also been fixed. - -=item * - -fork() correctly returns undef and sets EAGAIN when it runs out of -pseudo-process handles. - -=item * - -ExtUtils::MakeMaker now uses $ENV{LIB} to search for libraries. - -=item * - -UNC path handling is better when perl is built to support fork(). - -=item * - -A handle leak in socket handling has been fixed. - -=item * - -send() works from within a pseudo-process. - -=back - -Unless specifically qualified otherwise, the remainder of this document -covers changes between the 5.005 and 5.6.0 releases. - -=head1 Core Enhancements - -=head2 Interpreter cloning, threads, and concurrency - -Perl 5.6.0 introduces the beginnings of support for running multiple -interpreters concurrently in different threads. In conjunction with -the perl_clone() API call, which can be used to selectively duplicate -the state of any given interpreter, it is possible to compile a -piece of code once in an interpreter, clone that interpreter -one or more times, and run all the resulting interpreters in distinct -threads. - -On the Windows platform, this feature is used to emulate fork() at the -interpreter level. See L<perlfork> for details about that. - -This feature is still in evolution. It is eventually meant to be used -to selectively clone a subroutine and data reachable from that -subroutine in a separate interpreter and run the cloned subroutine -in a separate thread. Since there is no shared data between the -interpreters, little or no locking will be needed (unless parts of -the symbol table are explicitly shared). This is obviously intended -to be an easy-to-use replacement for the existing threads support. - -Support for cloning interpreters and interpreter concurrency can be -enabled using the -Dusethreads Configure option (see win32/Makefile for -how to enable it on Windows.) The resulting perl executable will be -functionally identical to one that was built with -Dmultiplicity, but -the perl_clone() API call will only be available in the former. - --Dusethreads enables the cpp macro USE_ITHREADS by default, which in turn -enables Perl source code changes that provide a clear separation between -the op tree and the data it operates with. The former is immutable, and -can therefore be shared between an interpreter and all of its clones, -while the latter is considered local to each interpreter, and is therefore -copied for each clone. - -Note that building Perl with the -Dusemultiplicity Configure option -is adequate if you wish to run multiple B<independent> interpreters -concurrently in different threads. -Dusethreads only provides the -additional functionality of the perl_clone() API call and other -support for running B<cloned> interpreters concurrently. - - NOTE: This is an experimental feature. Implementation details are - subject to change. - -=head2 Lexically scoped warning categories - -You can now control the granularity of warnings emitted by perl at a finer -level using the C<use warnings> pragma. L<warnings> and L<perllexwarn> -have copious documentation on this feature. - -=head2 Unicode and UTF-8 support - -Perl now uses UTF-8 as its internal representation for character -strings. The C<utf8> and C<bytes> pragmas are used to control this support -in the current lexical scope. See L<perlunicode>, L<utf8> and L<bytes> for -more information. - -This feature is expected to evolve quickly to support some form of I/O -disciplines that can be used to specify the kind of input and output data -(bytes or characters). Until that happens, additional modules from CPAN -will be needed to complete the toolkit for dealing with Unicode. - - NOTE: This should be considered an experimental feature. Implementation - details are subject to change. - -=head2 Support for interpolating named characters - -The new C<\N> escape interpolates named characters within strings. -For example, C<"Hi! \N{WHITE SMILING FACE}"> evaluates to a string -with a Unicode smiley face at the end. - -=head2 "our" declarations - -An "our" declaration introduces a value that can be best understood -as a lexically scoped symbolic alias to a global variable in the -package that was current where the variable was declared. This is -mostly useful as an alternative to the C<vars> pragma, but also provides -the opportunity to introduce typing and other attributes for such -variables. See L<perlfunc/our>. - -=head2 Support for strings represented as a vector of ordinals - -Literals of the form C<v1.2.3.4> are now parsed as a string composed -of characters with the specified ordinals. This is an alternative, more -readable way to construct (possibly Unicode) strings instead of -interpolating characters, as in C<"\x{1}\x{2}\x{3}\x{4}">. The leading -C<v> may be omitted if there are more than two ordinals, so C<1.2.3> is -parsed the same as C<v1.2.3>. - -Strings written in this form are also useful to represent version "numbers". -It is easy to compare such version "numbers" (which are really just plain -strings) using any of the usual string comparison operators C<eq>, C<ne>, -C<lt>, C<gt>, etc., or perform bitwise string operations on them using C<|>, -C<&>, etc. - -In conjunction with the new C<$^V> magic variable (which contains -the perl version as a string), such literals can be used as a readable way -to check if you're running a particular version of Perl: - - # this will parse in older versions of Perl also - if ($^V and $^V gt v5.6.0) { - # new features supported - } - -C<require> and C<use> also have some special magic to support such literals. -They will be interpreted as a version rather than as a module name: - - require v5.6.0; # croak if $^V lt v5.6.0 - use v5.6.0; # same, but croaks at compile-time - -Alternatively, the C<v> may be omitted if there is more than one dot: - - require 5.6.0; - use 5.6.0; - -Also, C<sprintf> and C<printf> support the Perl-specific format flag C<%v> -to print ordinals of characters in arbitrary strings: - - printf "v%vd", $^V; # prints current version, such as "v5.5.650" - printf "%*vX", ":", $addr; # formats IPv6 address - printf "%*vb", " ", $bits; # displays bitstring - -See L<perldata/"Scalar value constructors"> for additional information. - -=head2 Improved Perl version numbering system - -Beginning with Perl version 5.6.0, the version number convention has been -changed to a "dotted integer" scheme that is more commonly found in open -source projects. - -Maintenance versions of v5.6.0 will be released as v5.6.1, v5.6.2 etc. -The next development series following v5.6.0 will be numbered v5.7.x, -beginning with v5.7.0, and the next major production release following -v5.6.0 will be v5.8.0. - -The English module now sets $PERL_VERSION to $^V (a string value) rather -than C<$]> (a numeric value). (This is a potential incompatibility. -Send us a report via perlbug if you are affected by this.) - -The v1.2.3 syntax is also now legal in Perl. -See L<Support for strings represented as a vector of ordinals> for more on that. - -To cope with the new versioning system's use of at least three significant -digits for each version component, the method used for incrementing the -subversion number has also changed slightly. We assume that versions older -than v5.6.0 have been incrementing the subversion component in multiples of -10. Versions after v5.6.0 will increment them by 1. Thus, using the new -notation, 5.005_03 is the "same" as v5.5.30, and the first maintenance -version following v5.6.0 will be v5.6.1 (which should be read as being -equivalent to a floating point value of 5.006_001 in the older format, -stored in C<$]>). - -=head2 New syntax for declaring subroutine attributes - -Formerly, if you wanted to mark a subroutine as being a method call or -as requiring an automatic lock() when it is entered, you had to declare -that with a C<use attrs> pragma in the body of the subroutine. -That can now be accomplished with declaration syntax, like this: - - sub mymethod : locked method ; - ... - sub mymethod : locked method { - ... - } - - sub othermethod :locked :method ; - ... - sub othermethod :locked :method { - ... - } - - -(Note how only the first C<:> is mandatory, and whitespace surrounding -the C<:> is optional.) - -F<AutoSplit.pm> and F<SelfLoader.pm> have been updated to keep the attributes -with the stubs they provide. See L<attributes>. - -=head2 File and directory handles can be autovivified - -Similar to how constructs such as C<< $x->[0] >> autovivify a reference, -handle constructors (open(), opendir(), pipe(), socketpair(), sysopen(), -socket(), and accept()) now autovivify a file or directory handle -if the handle passed to them is an uninitialized scalar variable. This -allows the constructs such as C<open(my $fh, ...)> and C<open(local $fh,...)> -to be used to create filehandles that will conveniently be closed -automatically when the scope ends, provided there are no other references -to them. This largely eliminates the need for typeglobs when opening -filehandles that must be passed around, as in the following example: - - sub myopen { - open my $fh, "@_" - or die "Can't open '@_': $!"; - return $fh; - } - - { - my $f = myopen("</etc/motd"); - print <$f>; - # $f implicitly closed here - } - -=head2 open() with more than two arguments - -If open() is passed three arguments instead of two, the second argument -is used as the mode and the third argument is taken to be the file name. -This is primarily useful for protecting against unintended magic behavior -of the traditional two-argument form. See L<perlfunc/open>. - -=head2 64-bit support - -Any platform that has 64-bit integers either - - (1) natively as longs or ints - (2) via special compiler flags - (3) using long long or int64_t - -is able to use "quads" (64-bit integers) as follows: - -=over 4 - -=item * - -constants (decimal, hexadecimal, octal, binary) in the code - -=item * - -arguments to oct() and hex() - -=item * - -arguments to print(), printf() and sprintf() (flag prefixes ll, L, q) - -=item * - -printed as such - -=item * - -pack() and unpack() "q" and "Q" formats - -=item * - -in basic arithmetics: + - * / % (NOTE: operating close to the limits -of the integer values may produce surprising results) - -=item * - -in bit arithmetics: & | ^ ~ << >> (NOTE: these used to be forced -to be 32 bits wide but now operate on the full native width.) - -=item * - -vec() - -=back - -Note that unless you have the case (a) you will have to configure -and compile Perl using the -Duse64bitint Configure flag. - - NOTE: The Configure flags -Duselonglong and -Duse64bits have been - deprecated. Use -Duse64bitint instead. - -There are actually two modes of 64-bitness: the first one is achieved -using Configure -Duse64bitint and the second one using Configure --Duse64bitall. The difference is that the first one is minimal and -the second one maximal. The first works in more places than the second. - -The C<use64bitint> does only as much as is required to get 64-bit -integers into Perl (this may mean, for example, using "long longs") -while your memory may still be limited to 2 gigabytes (because your -pointers could still be 32-bit). Note that the name C<64bitint> does -not imply that your C compiler will be using 64-bit C<int>s (it might, -but it doesn't have to): the C<use64bitint> means that you will be -able to have 64 bits wide scalar values. - -The C<use64bitall> goes all the way by attempting to switch also -integers (if it can), longs (and pointers) to being 64-bit. This may -create an even more binary incompatible Perl than -Duse64bitint: the -resulting executable may not run at all in a 32-bit box, or you may -have to reboot/reconfigure/rebuild your operating system to be 64-bit -aware. - -Natively 64-bit systems like Alpha and Cray need neither -Duse64bitint -nor -Duse64bitall. - -Last but not least: note that due to Perl's habit of always using -floating point numbers, the quads are still not true integers. -When quads overflow their limits (0...18_446_744_073_709_551_615 unsigned, --9_223_372_036_854_775_808...9_223_372_036_854_775_807 signed), they -are silently promoted to floating point numbers, after which they will -start losing precision (in their lower digits). - - NOTE: 64-bit support is still experimental on most platforms. - Existing support only covers the LP64 data model. In particular, the - LLP64 data model is not yet supported. 64-bit libraries and system - APIs on many platforms have not stabilized--your mileage may vary. - -=head2 Large file support - -If you have filesystems that support "large files" (files larger than -2 gigabytes), you may now also be able to create and access them from -Perl. - - NOTE: The default action is to enable large file support, if - available on the platform. - -If the large file support is on, and you have a Fcntl constant -O_LARGEFILE, the O_LARGEFILE is automatically added to the flags -of sysopen(). - -Beware that unless your filesystem also supports "sparse files" seeking -to umpteen petabytes may be inadvisable. - -Note that in addition to requiring a proper file system to do large -files you may also need to adjust your per-process (or your -per-system, or per-process-group, or per-user-group) maximum filesize -limits before running Perl scripts that try to handle large files, -especially if you intend to write such files. - -Finally, in addition to your process/process group maximum filesize -limits, you may have quota limits on your filesystems that stop you -(your user id or your user group id) from using large files. - -Adjusting your process/user/group/file system/operating system limits -is outside the scope of Perl core language. For process limits, you -may try increasing the limits using your shell's limits/limit/ulimit -command before running Perl. The BSD::Resource extension (not -included with the standard Perl distribution) may also be of use, it -offers the getrlimit/setrlimit interface that can be used to adjust -process resource usage limits, including the maximum filesize limit. - -=head2 Long doubles - -In some systems you may be able to use long doubles to enhance the -range and precision of your double precision floating point numbers -(that is, Perl's numbers). Use Configure -Duselongdouble to enable -this support (if it is available). - -=head2 "more bits" - -You can "Configure -Dusemorebits" to turn on both the 64-bit support -and the long double support. - -=head2 Enhanced support for sort() subroutines - -Perl subroutines with a prototype of C<($$)>, and XSUBs in general, can -now be used as sort subroutines. In either case, the two elements to -be compared are passed as normal parameters in @_. See L<perlfunc/sort>. - -For unprototyped sort subroutines, the historical behavior of passing -the elements to be compared as the global variables $a and $b remains -unchanged. - -=head2 C<sort $coderef @foo> allowed - -sort() did not accept a subroutine reference as the comparison -function in earlier versions. This is now permitted. - -=head2 File globbing implemented internally - -Perl now uses the File::Glob implementation of the glob() operator -automatically. This avoids using an external csh process and the -problems associated with it. - - NOTE: This is currently an experimental feature. Interfaces and - implementation are subject to change. - -=head2 Support for CHECK blocks - -In addition to C<BEGIN>, C<INIT>, C<END>, C<DESTROY> and C<AUTOLOAD>, -subroutines named C<CHECK> are now special. These are queued up during -compilation and behave similar to END blocks, except they are called at -the end of compilation rather than at the end of execution. They cannot -be called directly. - -=head2 POSIX character class syntax [: :] supported - -For example to match alphabetic characters use /[[:alpha:]]/. -See L<perlre> for details. - -=head2 Better pseudo-random number generator - -In 5.005_0x and earlier, perl's rand() function used the C library -rand(3) function. As of 5.005_52, Configure tests for drand48(), -random(), and rand() (in that order) and picks the first one it finds. - -These changes should result in better random numbers from rand(). - -=head2 Improved C<qw//> operator - -The C<qw//> operator is now evaluated at compile time into a true list -instead of being replaced with a run time call to C<split()>. This -removes the confusing misbehaviour of C<qw//> in scalar context, which -had inherited that behaviour from split(). - -Thus: - - $foo = ($bar) = qw(a b c); print "$foo|$bar\n"; - -now correctly prints "3|a", instead of "2|a". - -=head2 Better worst-case behavior of hashes - -Small changes in the hashing algorithm have been implemented in -order to improve the distribution of lower order bits in the -hashed value. This is expected to yield better performance on -keys that are repeated sequences. - -=head2 pack() format 'Z' supported - -The new format type 'Z' is useful for packing and unpacking null-terminated -strings. See L<perlfunc/"pack">. - -=head2 pack() format modifier '!' supported - -The new format type modifier '!' is useful for packing and unpacking -native shorts, ints, and longs. See L<perlfunc/"pack">. - -=head2 pack() and unpack() support counted strings - -The template character '/' can be used to specify a counted string -type to be packed or unpacked. See L<perlfunc/"pack">. - -=head2 Comments in pack() templates - -The '#' character in a template introduces a comment up to -end of the line. This facilitates documentation of pack() -templates. - -=head2 Weak references - -In previous versions of Perl, you couldn't cache objects so as -to allow them to be deleted if the last reference from outside -the cache is deleted. The reference in the cache would hold a -reference count on the object and the objects would never be -destroyed. - -Another familiar problem is with circular references. When an -object references itself, its reference count would never go -down to zero, and it would not get destroyed until the program -is about to exit. - -Weak references solve this by allowing you to "weaken" any -reference, that is, make it not count towards the reference count. -When the last non-weak reference to an object is deleted, the object -is destroyed and all the weak references to the object are -automatically undef-ed. - -To use this feature, you need the WeakRef package from CPAN, which -contains additional documentation. - - NOTE: This is an experimental feature. Details are subject to change. - -=head2 Binary numbers supported - -Binary numbers are now supported as literals, in s?printf formats, and -C<oct()>: - - $answer = 0b101010; - printf "The answer is: %b\n", oct("0b101010"); - -=head2 Lvalue subroutines - -Subroutines can now return modifiable lvalues. -See L<perlsub/"Lvalue subroutines">. - - NOTE: This is an experimental feature. Details are subject to change. - -=head2 Some arrows may be omitted in calls through references - -Perl now allows the arrow to be omitted in many constructs -involving subroutine calls through references. For example, -C<< $foo[10]->('foo') >> may now be written C<$foo[10]('foo')>. -This is rather similar to how the arrow may be omitted from -C<< $foo[10]->{'foo'} >>. Note however, that the arrow is still -required for C<< foo(10)->('bar') >>. - -=head2 Boolean assignment operators are legal lvalues - -Constructs such as C<($a ||= 2) += 1> are now allowed. - -=head2 exists() is supported on subroutine names - -The exists() builtin now works on subroutine names. A subroutine -is considered to exist if it has been declared (even if implicitly). -See L<perlfunc/exists> for examples. - -=head2 exists() and delete() are supported on array elements - -The exists() and delete() builtins now work on simple arrays as well. -The behavior is similar to that on hash elements. - -exists() can be used to check whether an array element has been -initialized. This avoids autovivifying array elements that don't exist. -If the array is tied, the EXISTS() method in the corresponding tied -package will be invoked. - -delete() may be used to remove an element from the array and return -it. The array element at that position returns to its uninitialized -state, so that testing for the same element with exists() will return -false. If the element happens to be the one at the end, the size of -the array also shrinks up to the highest element that tests true for -exists(), or 0 if none such is found. If the array is tied, the DELETE() -method in the corresponding tied package will be invoked. - -See L<perlfunc/exists> and L<perlfunc/delete> for examples. - -=head2 Pseudo-hashes work better - -Dereferencing some types of reference values in a pseudo-hash, -such as C<< $ph->{foo}[1] >>, was accidentally disallowed. This has -been corrected. - -When applied to a pseudo-hash element, exists() now reports whether -the specified value exists, not merely if the key is valid. - -delete() now works on pseudo-hashes. When given a pseudo-hash element -or slice it deletes the values corresponding to the keys (but not the keys -themselves). See L<perlref/"Pseudo-hashes: Using an array as a hash">. - -Pseudo-hash slices with constant keys are now optimized to array lookups -at compile-time. - -List assignments to pseudo-hash slices are now supported. - -The C<fields> pragma now provides ways to create pseudo-hashes, via -fields::new() and fields::phash(). See L<fields>. - - NOTE: The pseudo-hash data type continues to be experimental. - Limiting oneself to the interface elements provided by the - fields pragma will provide protection from any future changes. - -=head2 Automatic flushing of output buffers - -fork(), exec(), system(), qx//, and pipe open()s now flush buffers -of all files opened for output when the operation was attempted. This -mostly eliminates confusing buffering mishaps suffered by users unaware -of how Perl internally handles I/O. - -This is not supported on some platforms like Solaris where a suitably -correct implementation of fflush(NULL) isn't available. - -=head2 Better diagnostics on meaningless filehandle operations - -Constructs such as C<< open(<FH>) >> and C<< close(<FH>) >> -are compile time errors. Attempting to read from filehandles that -were opened only for writing will now produce warnings (just as -writing to read-only filehandles does). - -=head2 Where possible, buffered data discarded from duped input filehandle - -C<< open(NEW, "<&OLD") >> now attempts to discard any data that -was previously read and buffered in C<OLD> before duping the handle. -On platforms where doing this is allowed, the next read operation -on C<NEW> will return the same data as the corresponding operation -on C<OLD>. Formerly, it would have returned the data from the start -of the following disk block instead. - -=head2 eof() has the same old magic as <> - -C<eof()> would return true if no attempt to read from C<< <> >> had -yet been made. C<eof()> has been changed to have a little magic of its -own, it now opens the C<< <> >> files. - -=head2 binmode() can be used to set :crlf and :raw modes - -binmode() now accepts a second argument that specifies a discipline -for the handle in question. The two pseudo-disciplines ":raw" and -":crlf" are currently supported on DOS-derivative platforms. -See L<perlfunc/"binmode"> and L<open>. - -=head2 C<-T> filetest recognizes UTF-8 encoded files as "text" - -The algorithm used for the C<-T> filetest has been enhanced to -correctly identify UTF-8 content as "text". - -=head2 system(), backticks and pipe open now reflect exec() failure - -On Unix and similar platforms, system(), qx() and open(FOO, "cmd |") -etc., are implemented via fork() and exec(). When the underlying -exec() fails, earlier versions did not report the error properly, -since the exec() happened to be in a different process. - -The child process now communicates with the parent about the -error in launching the external command, which allows these -constructs to return with their usual error value and set $!. - -=head2 Improved diagnostics - -Line numbers are no longer suppressed (under most likely circumstances) -during the global destruction phase. - -Diagnostics emitted from code running in threads other than the main -thread are now accompanied by the thread ID. - -Embedded null characters in diagnostics now actually show up. They -used to truncate the message in prior versions. - -$foo::a and $foo::b are now exempt from "possible typo" warnings only -if sort() is encountered in package C<foo>. - -Unrecognized alphabetic escapes encountered when parsing quote -constructs now generate a warning, since they may take on new -semantics in later versions of Perl. - -Many diagnostics now report the internal operation in which the warning -was provoked, like so: - - Use of uninitialized value in concatenation (.) at (eval 1) line 1. - Use of uninitialized value in print at (eval 1) line 1. - -Diagnostics that occur within eval may also report the file and line -number where the eval is located, in addition to the eval sequence -number and the line number within the evaluated text itself. For -example: - - Not enough arguments for scalar at (eval 4)[newlib/perl5db.pl:1411] line 2, at EOF - -=head2 Diagnostics follow STDERR - -Diagnostic output now goes to whichever file the C<STDERR> handle -is pointing at, instead of always going to the underlying C runtime -library's C<stderr>. - -=head2 More consistent close-on-exec behavior - -On systems that support a close-on-exec flag on filehandles, the -flag is now set for any handles created by pipe(), socketpair(), -socket(), and accept(), if that is warranted by the value of $^F -that may be in effect. Earlier versions neglected to set the flag -for handles created with these operators. See L<perlfunc/pipe>, -L<perlfunc/socketpair>, L<perlfunc/socket>, L<perlfunc/accept>, -and L<perlvar/$^F>. - -=head2 syswrite() ease-of-use - -The length argument of C<syswrite()> has become optional. - -=head2 Better syntax checks on parenthesized unary operators - -Expressions such as: - - print defined(&foo,&bar,&baz); - print uc("foo","bar","baz"); - undef($foo,&bar); - -used to be accidentally allowed in earlier versions, and produced -unpredictable behaviour. Some produced ancillary warnings -when used in this way; others silently did the wrong thing. - -The parenthesized forms of most unary operators that expect a single -argument now ensure that they are not called with more than one -argument, making the cases shown above syntax errors. The usual -behaviour of: - - print defined &foo, &bar, &baz; - print uc "foo", "bar", "baz"; - undef $foo, &bar; - -remains unchanged. See L<perlop>. - -=head2 Bit operators support full native integer width - -The bit operators (& | ^ ~ << >>) now operate on the full native -integral width (the exact size of which is available in $Config{ivsize}). -For example, if your platform is either natively 64-bit or if Perl -has been configured to use 64-bit integers, these operations apply -to 8 bytes (as opposed to 4 bytes on 32-bit platforms). -For portability, be sure to mask off the excess bits in the result of -unary C<~>, e.g., C<~$x & 0xffffffff>. - -=head2 Improved security features - -More potentially unsafe operations taint their results for improved -security. - -The C<passwd> and C<shell> fields returned by the getpwent(), getpwnam(), -and getpwuid() are now tainted, because the user can affect their own -encrypted password and login shell. - -The variable modified by shmread(), and messages returned by msgrcv() -(and its object-oriented interface IPC::SysV::Msg::rcv) are also tainted, -because other untrusted processes can modify messages and shared memory -segments for their own nefarious purposes. - -=head2 More functional bareword prototype (*) - -Bareword prototypes have been rationalized to enable them to be used -to override builtins that accept barewords and interpret them in -a special way, such as C<require> or C<do>. - -Arguments prototyped as C<*> will now be visible within the subroutine -as either a simple scalar or as a reference to a typeglob. -See L<perlsub/Prototypes>. - -=head2 C<require> and C<do> may be overridden - -C<require> and C<do 'file'> operations may be overridden locally -by importing subroutines of the same name into the current package -(or globally by importing them into the CORE::GLOBAL:: namespace). -Overriding C<require> will also affect C<use>, provided the override -is visible at compile-time. -See L<perlsub/"Overriding Built-in Functions">. - -=head2 $^X variables may now have names longer than one character - -Formerly, $^X was synonymous with ${"\cX"}, but $^XY was a syntax -error. Now variable names that begin with a control character may be -arbitrarily long. However, for compatibility reasons, these variables -I<must> be written with explicit braces, as C<${^XY}> for example. -C<${^XYZ}> is synonymous with ${"\cXYZ"}. Variable names with more -than one control character, such as C<${^XY^Z}>, are illegal. - -The old syntax has not changed. As before, `^X' may be either a -literal control-X character or the two-character sequence `caret' plus -`X'. When braces are omitted, the variable name stops after the -control character. Thus C<"$^XYZ"> continues to be synonymous with -C<$^X . "YZ"> as before. - -As before, lexical variables may not have names beginning with control -characters. As before, variables whose names begin with a control -character are always forced to be in package `main'. All such variables -are reserved for future extensions, except those that begin with -C<^_>, which may be used by user programs and are guaranteed not to -acquire special meaning in any future version of Perl. - -=head2 New variable $^C reflects C<-c> switch - -C<$^C> has a boolean value that reflects whether perl is being run -in compile-only mode (i.e. via the C<-c> switch). Since -BEGIN blocks are executed under such conditions, this variable -enables perl code to determine whether actions that make sense -only during normal running are warranted. See L<perlvar>. - -=head2 New variable $^V contains Perl version as a string - -C<$^V> contains the Perl version number as a string composed of -characters whose ordinals match the version numbers, i.e. v5.6.0. -This may be used in string comparisons. - -See C<Support for strings represented as a vector of ordinals> for an -example. - -=head2 Optional Y2K warnings - -If Perl is built with the cpp macro C<PERL_Y2KWARN> defined, -it emits optional warnings when concatenating the number 19 -with another number. - -This behavior must be specifically enabled when running Configure. -See F<INSTALL> and F<README.Y2K>. - -=head2 Arrays now always interpolate into double-quoted strings - -In double-quoted strings, arrays now interpolate, no matter what. The -behavior in earlier versions of perl 5 was that arrays would interpolate -into strings if the array had been mentioned before the string was -compiled, and otherwise Perl would raise a fatal compile-time error. -In versions 5.000 through 5.003, the error was - - Literal @example now requires backslash - -In versions 5.004_01 through 5.6.0, the error was - - In string, @example now must be written as \@example - -The idea here was to get people into the habit of writing -C<"fred\@example.com"> when they wanted a literal C<@> sign, just as -they have always written C<"Give me back my \$5"> when they wanted a -literal C<$> sign. - -Starting with 5.6.1, when Perl now sees an C<@> sign in a -double-quoted string, it I<always> attempts to interpolate an array, -regardless of whether or not the array has been used or declared -already. The fatal error has been downgraded to an optional warning: - - Possible unintended interpolation of @example in string - -This warns you that C<"fred@example.com"> is going to turn into -C<fred.com> if you don't backslash the C<@>. -See http://www.plover.com/~mjd/perl/at-error.html for more details -about the history here. - -=head1 Modules and Pragmata - -=head2 Modules - -=over 4 - -=item attributes - -While used internally by Perl as a pragma, this module also -provides a way to fetch subroutine and variable attributes. -See L<attributes>. - -=item B - -The Perl Compiler suite has been extensively reworked for this -release. More of the standard Perl testsuite passes when run -under the Compiler, but there is still a significant way to -go to achieve production quality compiled executables. - - NOTE: The Compiler suite remains highly experimental. The - generated code may not be correct, even when it manages to execute - without errors. - -=item Benchmark - -Overall, Benchmark results exhibit lower average error and better timing -accuracy. - -You can now run tests for I<n> seconds instead of guessing the right -number of tests to run: e.g., timethese(-5, ...) will run each -code for at least 5 CPU seconds. Zero as the "number of repetitions" -means "for at least 3 CPU seconds". The output format has also -changed. For example: - - use Benchmark;$x=3;timethese(-5,{a=>sub{$x*$x},b=>sub{$x**2}}) - -will now output something like this: - - Benchmark: running a, b, each for at least 5 CPU seconds... - a: 5 wallclock secs ( 5.77 usr + 0.00 sys = 5.77 CPU) @ 200551.91/s (n=1156516) - b: 4 wallclock secs ( 5.00 usr + 0.02 sys = 5.02 CPU) @ 159605.18/s (n=800686) - -New features: "each for at least N CPU seconds...", "wallclock secs", -and the "@ operations/CPU second (n=operations)". - -timethese() now returns a reference to a hash of Benchmark objects containing -the test results, keyed on the names of the tests. - -timethis() now returns the iterations field in the Benchmark result object -instead of 0. - -timethese(), timethis(), and the new cmpthese() (see below) can also take -a format specifier of 'none' to suppress output. - -A new function countit() is just like timeit() except that it takes a -TIME instead of a COUNT. - -A new function cmpthese() prints a chart comparing the results of each test -returned from a timethese() call. For each possible pair of tests, the -percentage speed difference (iters/sec or seconds/iter) is shown. - -For other details, see L<Benchmark>. - -=item ByteLoader - -The ByteLoader is a dedicated extension to generate and run -Perl bytecode. See L<ByteLoader>. - -=item constant - -References can now be used. - -The new version also allows a leading underscore in constant names, but -disallows a double leading underscore (as in "__LINE__"). Some other names -are disallowed or warned against, including BEGIN, END, etc. Some names -which were forced into main:: used to fail silently in some cases; now they're -fatal (outside of main::) and an optional warning (inside of main::). -The ability to detect whether a constant had been set with a given name has -been added. - -See L<constant>. - -=item charnames - -This pragma implements the C<\N> string escape. See L<charnames>. - -=item Data::Dumper - -A C<Maxdepth> setting can be specified to avoid venturing -too deeply into deep data structures. See L<Data::Dumper>. - -The XSUB implementation of Dump() is now automatically called if the -C<Useqq> setting is not in use. - -Dumping C<qr//> objects works correctly. - -=item DB - -C<DB> is an experimental module that exposes a clean abstraction -to Perl's debugging API. - -=item DB_File - -DB_File can now be built with Berkeley DB versions 1, 2 or 3. -See C<ext/DB_File/Changes>. - -=item Devel::DProf - -Devel::DProf, a Perl source code profiler has been added. See -L<Devel::DProf> and L<dprofpp>. - -=item Devel::Peek - -The Devel::Peek module provides access to the internal representation -of Perl variables and data. It is a data debugging tool for the XS programmer. - -=item Dumpvalue - -The Dumpvalue module provides screen dumps of Perl data. - -=item DynaLoader - -DynaLoader now supports a dl_unload_file() function on platforms that -support unloading shared objects using dlclose(). - -Perl can also optionally arrange to unload all extension shared objects -loaded by Perl. To enable this, build Perl with the Configure option -C<-Accflags=-DDL_UNLOAD_ALL_AT_EXIT>. (This maybe useful if you are -using Apache with mod_perl.) - -=item English - -$PERL_VERSION now stands for C<$^V> (a string value) rather than for C<$]> -(a numeric value). - -=item Env - -Env now supports accessing environment variables like PATH as array -variables. - -=item Fcntl - -More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for -large file (more than 4GB) access (NOTE: the O_LARGEFILE is -automatically added to sysopen() flags if large file support has been -configured, as is the default), Free/Net/OpenBSD locking behaviour -flags F_FLOCK, F_POSIX, Linux F_SHLCK, and O_ACCMODE: the combined -mask of O_RDONLY, O_WRONLY, and O_RDWR. The seek()/sysseek() -constants SEEK_SET, SEEK_CUR, and SEEK_END are available via the -C<:seek> tag. The chmod()/stat() S_IF* constants and S_IS* functions -are available via the C<:mode> tag. - -=item File::Compare - -A compare_text() function has been added, which allows custom -comparison functions. See L<File::Compare>. - -=item File::Find - -File::Find now works correctly when the wanted() function is either -autoloaded or is a symbolic reference. - -A bug that caused File::Find to lose track of the working directory -when pruning top-level directories has been fixed. - -File::Find now also supports several other options to control its -behavior. It can follow symbolic links if the C<follow> option is -specified. Enabling the C<no_chdir> option will make File::Find skip -changing the current directory when walking directories. The C<untaint> -flag can be useful when running with taint checks enabled. - -See L<File::Find>. - -=item File::Glob - -This extension implements BSD-style file globbing. By default, -it will also be used for the internal implementation of the glob() -operator. See L<File::Glob>. - -=item File::Spec - -New methods have been added to the File::Spec module: devnull() returns -the name of the null device (/dev/null on Unix) and tmpdir() the name of -the temp directory (normally /tmp on Unix). There are now also methods -to convert between absolute and relative filenames: abs2rel() and -rel2abs(). For compatibility with operating systems that specify volume -names in file paths, the splitpath(), splitdir(), and catdir() methods -have been added. - -=item File::Spec::Functions - -The new File::Spec::Functions modules provides a function interface -to the File::Spec module. Allows shorthand - - $fullname = catfile($dir1, $dir2, $file); - -instead of - - $fullname = File::Spec->catfile($dir1, $dir2, $file); - -=item Getopt::Long - -Getopt::Long licensing has changed to allow the Perl Artistic License -as well as the GPL. It used to be GPL only, which got in the way of -non-GPL applications that wanted to use Getopt::Long. - -Getopt::Long encourages the use of Pod::Usage to produce help -messages. For example: - - use Getopt::Long; - use Pod::Usage; - my $man = 0; - my $help = 0; - GetOptions('help|?' => \$help, man => \$man) or pod2usage(2); - pod2usage(1) if $help; - pod2usage(-exitstatus => 0, -verbose => 2) if $man; - - __END__ - - =head1 NAME - - sample - Using GetOpt::Long and Pod::Usage - - =head1 SYNOPSIS - - sample [options] [file ...] - - Options: - -help brief help message - -man full documentation - - =head1 OPTIONS - - =over 8 - - =item B<-help> - - Print a brief help message and exits. - - =item B<-man> - - Prints the manual page and exits. - - =back - - =head1 DESCRIPTION - - B<This program> will read the given input file(s) and do something - useful with the contents thereof. - - =cut - -See L<Pod::Usage> for details. - -A bug that prevented the non-option call-back <> from being -specified as the first argument has been fixed. - -To specify the characters < and > as option starters, use ><. Note, -however, that changing option starters is strongly deprecated. - -=item IO - -write() and syswrite() will now accept a single-argument -form of the call, for consistency with Perl's syswrite(). - -You can now create a TCP-based IO::Socket::INET without forcing -a connect attempt. This allows you to configure its options -(like making it non-blocking) and then call connect() manually. - -A bug that prevented the IO::Socket::protocol() accessor -from ever returning the correct value has been corrected. - -IO::Socket::connect now uses non-blocking IO instead of alarm() -to do connect timeouts. - -IO::Socket::accept now uses select() instead of alarm() for doing -timeouts. - -IO::Socket::INET->new now sets $! correctly on failure. $@ is -still set for backwards compatibility. - -=item JPL - -Java Perl Lingo is now distributed with Perl. See jpl/README -for more information. - -=item lib - -C<use lib> now weeds out any trailing duplicate entries. -C<no lib> removes all named entries. - -=item Math::BigInt - -The bitwise operations C<<< << >>>, C<<< >> >>>, C<&>, C<|>, -and C<~> are now supported on bigints. - -=item Math::Complex - -The accessor methods Re, Im, arg, abs, rho, and theta can now also -act as mutators (accessor $z->Re(), mutator $z->Re(3)). - -The class method C<display_format> and the corresponding object method -C<display_format>, in addition to accepting just one argument, now can -also accept a parameter hash. Recognized keys of a parameter hash are -C<"style">, which corresponds to the old one parameter case, and two -new parameters: C<"format">, which is a printf()-style format string -(defaults usually to C<"%.15g">, you can revert to the default by -setting the format string to C<undef>) used for both parts of a -complex number, and C<"polar_pretty_print"> (defaults to true), -which controls whether an attempt is made to try to recognize small -multiples and rationals of pi (2pi, pi/2) at the argument (angle) of a -polar complex number. - -The potentially disruptive change is that in list context both methods -now I<return the parameter hash>, instead of only the value of the -C<"style"> parameter. - -=item Math::Trig - -A little bit of radial trigonometry (cylindrical and spherical), -radial coordinate conversions, and the great circle distance were added. - -=item Pod::Parser, Pod::InputObjects - -Pod::Parser is a base class for parsing and selecting sections of -pod documentation from an input stream. This module takes care of -identifying pod paragraphs and commands in the input and hands off the -parsed paragraphs and commands to user-defined methods which are free -to interpret or translate them as they see fit. - -Pod::InputObjects defines some input objects needed by Pod::Parser, and -for advanced users of Pod::Parser that need more about a command besides -its name and text. - -As of release 5.6.0 of Perl, Pod::Parser is now the officially sanctioned -"base parser code" recommended for use by all pod2xxx translators. -Pod::Text (pod2text) and Pod::Man (pod2man) have already been converted -to use Pod::Parser and efforts to convert Pod::HTML (pod2html) are already -underway. For any questions or comments about pod parsing and translating -issues and utilities, please use the pod-people@perl.org mailing list. - -For further information, please see L<Pod::Parser> and L<Pod::InputObjects>. - -=item Pod::Checker, podchecker - -This utility checks pod files for correct syntax, according to -L<perlpod>. Obvious errors are flagged as such, while warnings are -printed for mistakes that can be handled gracefully. The checklist is -not complete yet. See L<Pod::Checker>. - -=item Pod::ParseUtils, Pod::Find - -These modules provide a set of gizmos that are useful mainly for pod -translators. L<Pod::Find|Pod::Find> traverses directory structures and -returns found pod files, along with their canonical names (like -C<File::Spec::Unix>). L<Pod::ParseUtils|Pod::ParseUtils> contains -B<Pod::List> (useful for storing pod list information), B<Pod::Hyperlink> -(for parsing the contents of C<LE<lt>E<gt>> sequences) and B<Pod::Cache> -(for caching information about pod files, e.g., link nodes). - -=item Pod::Select, podselect - -Pod::Select is a subclass of Pod::Parser which provides a function -named "podselect()" to filter out user-specified sections of raw pod -documentation from an input stream. podselect is a script that provides -access to Pod::Select from other scripts to be used as a filter. -See L<Pod::Select>. - -=item Pod::Usage, pod2usage - -Pod::Usage provides the function "pod2usage()" to print usage messages for -a Perl script based on its embedded pod documentation. The pod2usage() -function is generally useful to all script authors since it lets them -write and maintain a single source (the pods) for documentation, thus -removing the need to create and maintain redundant usage message text -consisting of information already in the pods. - -There is also a pod2usage script which can be used from other kinds of -scripts to print usage messages from pods (even for non-Perl scripts -with pods embedded in comments). - -For details and examples, please see L<Pod::Usage>. - -=item Pod::Text and Pod::Man - -Pod::Text has been rewritten to use Pod::Parser. While pod2text() is -still available for backwards compatibility, the module now has a new -preferred interface. See L<Pod::Text> for the details. The new Pod::Text -module is easily subclassed for tweaks to the output, and two such -subclasses (Pod::Text::Termcap for man-page-style bold and underlining -using termcap information, and Pod::Text::Color for markup with ANSI color -sequences) are now standard. - -pod2man has been turned into a module, Pod::Man, which also uses -Pod::Parser. In the process, several outstanding bugs related to quotes -in section headers, quoting of code escapes, and nested lists have been -fixed. pod2man is now a wrapper script around this module. - -=item SDBM_File - -An EXISTS method has been added to this module (and sdbm_exists() has -been added to the underlying sdbm library), so one can now call exists -on an SDBM_File tied hash and get the correct result, rather than a -runtime error. - -A bug that may have caused data loss when more than one disk block -happens to be read from the database in a single FETCH() has been -fixed. - -=item Sys::Syslog - -Sys::Syslog now uses XSUBs to access facilities from syslog.h so it -no longer requires syslog.ph to exist. - -=item Sys::Hostname - -Sys::Hostname now uses XSUBs to call the C library's gethostname() or -uname() if they exist. - -=item Term::ANSIColor - -Term::ANSIColor is a very simple module to provide easy and readable -access to the ANSI color and highlighting escape sequences, supported by -most ANSI terminal emulators. It is now included standard. - -=item Time::Local - -The timelocal() and timegm() functions used to silently return bogus -results when the date fell outside the machine's integer range. They -now consistently croak() if the date falls in an unsupported range. - -=item Win32 - -The error return value in list context has been changed for all functions -that return a list of values. Previously these functions returned a list -with a single element C<undef> if an error occurred. Now these functions -return the empty list in these situations. This applies to the following -functions: - - Win32::FsType - Win32::GetOSVersion - -The remaining functions are unchanged and continue to return C<undef> on -error even in list context. - -The Win32::SetLastError(ERROR) function has been added as a complement -to the Win32::GetLastError() function. - -The new Win32::GetFullPathName(FILENAME) returns the full absolute -pathname for FILENAME in scalar context. In list context it returns -a two-element list containing the fully qualified directory name and -the filename. See L<Win32>. - -=item XSLoader - -The XSLoader extension is a simpler alternative to DynaLoader. -See L<XSLoader>. - -=item DBM Filters - -A new feature called "DBM Filters" has been added to all the -DBM modules--DB_File, GDBM_File, NDBM_File, ODBM_File, and SDBM_File. -DBM Filters add four new methods to each DBM module: - - filter_store_key - filter_store_value - filter_fetch_key - filter_fetch_value - -These can be used to filter key-value pairs before the pairs are -written to the database or just after they are read from the database. -See L<perldbmfilter> for further information. - -=back - -=head2 Pragmata - -C<use attrs> is now obsolete, and is only provided for -backward-compatibility. It's been replaced by the C<sub : attributes> -syntax. See L<perlsub/"Subroutine Attributes"> and L<attributes>. - -Lexical warnings pragma, C<use warnings;>, to control optional warnings. -See L<perllexwarn>. - -C<use filetest> to control the behaviour of filetests (C<-r> C<-w> -...). Currently only one subpragma implemented, "use filetest -'access';", that uses access(2) or equivalent to check permissions -instead of using stat(2) as usual. This matters in filesystems -where there are ACLs (access control lists): the stat(2) might lie, -but access(2) knows better. - -The C<open> pragma can be used to specify default disciplines for -handle constructors (e.g. open()) and for qx//. The two -pseudo-disciplines C<:raw> and C<:crlf> are currently supported on -DOS-derivative platforms (i.e. where binmode is not a no-op). -See also L</"binmode() can be used to set :crlf and :raw modes">. - -=head1 Utility Changes - -=head2 dprofpp - -C<dprofpp> is used to display profile data generated using C<Devel::DProf>. -See L<dprofpp>. - -=head2 find2perl - -The C<find2perl> utility now uses the enhanced features of the File::Find -module. The -depth and -follow options are supported. Pod documentation -is also included in the script. - -=head2 h2xs - -The C<h2xs> tool can now work in conjunction with C<C::Scan> (available -from CPAN) to automatically parse real-life header files. The C<-M>, -C<-a>, C<-k>, and C<-o> options are new. - -=head2 perlcc - -C<perlcc> now supports the C and Bytecode backends. By default, -it generates output from the simple C backend rather than the -optimized C backend. - -Support for non-Unix platforms has been improved. - -=head2 perldoc - -C<perldoc> has been reworked to avoid possible security holes. -It will not by default let itself be run as the superuser, but you -may still use the B<-U> switch to try to make it drop privileges -first. - -=head2 The Perl Debugger - -Many bug fixes and enhancements were added to F<perl5db.pl>, the -Perl debugger. The help documentation was rearranged. New commands -include C<< < ? >>, C<< > ? >>, and C<< { ? >> to list out current -actions, C<man I<docpage>> to run your doc viewer on some perl -docset, and support for quoted options. The help information was -rearranged, and should be viewable once again if you're using B<less> -as your pager. A serious security hole was plugged--you should -immediately remove all older versions of the Perl debugger as -installed in previous releases, all the way back to perl3, from -your system to avoid being bitten by this. - -=head1 Improved Documentation - -Many of the platform-specific README files are now part of the perl -installation. See L<perl> for the complete list. - -=over 4 - -=item perlapi.pod - -The official list of public Perl API functions. - -=item perlboot.pod - -A tutorial for beginners on object-oriented Perl. - -=item perlcompile.pod - -An introduction to using the Perl Compiler suite. - -=item perldbmfilter.pod - -A howto document on using the DBM filter facility. - -=item perldebug.pod - -All material unrelated to running the Perl debugger, plus all -low-level guts-like details that risked crushing the casual user -of the debugger, have been relocated from the old manpage to the -next entry below. - -=item perldebguts.pod - -This new manpage contains excessively low-level material not related -to the Perl debugger, but slightly related to debugging Perl itself. -It also contains some arcane internal details of how the debugging -process works that may only be of interest to developers of Perl -debuggers. - -=item perlfork.pod - -Notes on the fork() emulation currently available for the Windows platform. - -=item perlfilter.pod - -An introduction to writing Perl source filters. - -=item perlhack.pod - -Some guidelines for hacking the Perl source code. - -=item perlintern.pod - -A list of internal functions in the Perl source code. -(List is currently empty.) - -=item perllexwarn.pod - -Introduction and reference information about lexically scoped -warning categories. - -=item perlnumber.pod - -Detailed information about numbers as they are represented in Perl. - -=item perlopentut.pod - -A tutorial on using open() effectively. - -=item perlreftut.pod - -A tutorial that introduces the essentials of references. - -=item perltootc.pod - -A tutorial on managing class data for object modules. - -=item perltodo.pod - -Discussion of the most often wanted features that may someday be -supported in Perl. - -=item perlunicode.pod - -An introduction to Unicode support features in Perl. - -=back - -=head1 Performance enhancements - -=head2 Simple sort() using { $a <=> $b } and the like are optimized - -Many common sort() operations using a simple inlined block are now -optimized for faster performance. - -=head2 Optimized assignments to lexical variables - -Certain operations in the RHS of assignment statements have been -optimized to directly set the lexical variable on the LHS, -eliminating redundant copying overheads. - -=head2 Faster subroutine calls - -Minor changes in how subroutine calls are handled internally -provide marginal improvements in performance. - -=head2 delete(), each(), values() and hash iteration are faster - -The hash values returned by delete(), each(), values() and hashes in a -list context are the actual values in the hash, instead of copies. -This results in significantly better performance, because it eliminates -needless copying in most situations. - -=head1 Installation and Configuration Improvements - -=head2 -Dusethreads means something different - -The -Dusethreads flag now enables the experimental interpreter-based thread -support by default. To get the flavor of experimental threads that was in -5.005 instead, you need to run Configure with "-Dusethreads -Duse5005threads". - -As of v5.6.0, interpreter-threads support is still lacking a way to -create new threads from Perl (i.e., C<use Thread;> will not work with -interpreter threads). C<use Thread;> continues to be available when you -specify the -Duse5005threads option to Configure, bugs and all. - - NOTE: Support for threads continues to be an experimental feature. - Interfaces and implementation are subject to sudden and drastic changes. - -=head2 New Configure flags - -The following new flags may be enabled on the Configure command line -by running Configure with C<-Dflag>. - - usemultiplicity - usethreads useithreads (new interpreter threads: no Perl API yet) - usethreads use5005threads (threads as they were in 5.005) - - use64bitint (equal to now deprecated 'use64bits') - use64bitall - - uselongdouble - usemorebits - uselargefiles - usesocks (only SOCKS v5 supported) - -=head2 Threadedness and 64-bitness now more daring - -The Configure options enabling the use of threads and the use of -64-bitness are now more daring in the sense that they no more have an -explicit list of operating systems of known threads/64-bit -capabilities. In other words: if your operating system has the -necessary APIs and datatypes, you should be able just to go ahead and -use them, for threads by Configure -Dusethreads, and for 64 bits -either explicitly by Configure -Duse64bitint or implicitly if your -system has 64-bit wide datatypes. See also L<"64-bit support">. - -=head2 Long Doubles - -Some platforms have "long doubles", floating point numbers of even -larger range than ordinary "doubles". To enable using long doubles for -Perl's scalars, use -Duselongdouble. - -=head2 -Dusemorebits - -You can enable both -Duse64bitint and -Duselongdouble with -Dusemorebits. -See also L<"64-bit support">. - -=head2 -Duselargefiles - -Some platforms support system APIs that are capable of handling large files -(typically, files larger than two gigabytes). Perl will try to use these -APIs if you ask for -Duselargefiles. - -See L<"Large file support"> for more information. - -=head2 installusrbinperl - -You can use "Configure -Uinstallusrbinperl" which causes installperl -to skip installing perl also as /usr/bin/perl. This is useful if you -prefer not to modify /usr/bin for some reason or another but harmful -because many scripts assume to find Perl in /usr/bin/perl. - -=head2 SOCKS support - -You can use "Configure -Dusesocks" which causes Perl to probe -for the SOCKS proxy protocol library (v5, not v4). For more information -on SOCKS, see: - - http://www.socks.nec.com/ - -=head2 C<-A> flag - -You can "post-edit" the Configure variables using the Configure C<-A> -switch. The editing happens immediately after the platform specific -hints files have been processed but before the actual configuration -process starts. Run C<Configure -h> to find out the full C<-A> syntax. - -=head2 Enhanced Installation Directories - -The installation structure has been enriched to improve the support -for maintaining multiple versions of perl, to provide locations for -vendor-supplied modules, scripts, and manpages, and to ease maintenance -of locally-added modules, scripts, and manpages. See the section on -Installation Directories in the INSTALL file for complete details. -For most users building and installing from source, the defaults should -be fine. - -If you previously used C<Configure -Dsitelib> or C<-Dsitearch> to set -special values for library directories, you might wish to consider using -the new C<-Dsiteprefix> setting instead. Also, if you wish to re-use a -config.sh file from an earlier version of perl, you should be sure to -check that Configure makes sensible choices for the new directories. -See INSTALL for complete details. - -=head2 gcc automatically tried if 'cc' does not seem to be working - -In many platforms the vendor-supplied 'cc' is too stripped-down to -build Perl (basically, the 'cc' doesn't do ANSI C). If this seems -to be the case and the 'cc' does not seem to be the GNU C compiler -'gcc', an automatic attempt is made to find and use 'gcc' instead. - -=head1 Platform specific changes - -=head2 Supported platforms - -=over 4 - -=item * - -The Mach CThreads (NEXTSTEP, OPENSTEP) are now supported by the Thread -extension. - -=item * - -GNU/Hurd is now supported. - -=item * - -Rhapsody/Darwin is now supported. - -=item * - -EPOC is now supported (on Psion 5). - -=item * - -The cygwin port (formerly cygwin32) has been greatly improved. - -=back - -=head2 DOS - -=over 4 - -=item * - -Perl now works with djgpp 2.02 (and 2.03 alpha). - -=item * - -Environment variable names are not converted to uppercase any more. - -=item * - -Incorrect exit codes from backticks have been fixed. - -=item * - -This port continues to use its own builtin globbing (not File::Glob). - -=back - -=head2 OS390 (OpenEdition MVS) - -Support for this EBCDIC platform has not been renewed in this release. -There are difficulties in reconciling Perl's standardization on UTF-8 -as its internal representation for characters with the EBCDIC character -set, because the two are incompatible. - -It is unclear whether future versions will renew support for this -platform, but the possibility exists. - -=head2 VMS - -Numerous revisions and extensions to configuration, build, testing, and -installation process to accommodate core changes and VMS-specific options. - -Expand %ENV-handling code to allow runtime mapping to logical names, -CLI symbols, and CRTL environ array. - -Extension of subprocess invocation code to accept filespecs as command -"verbs". - -Add to Perl command line processing the ability to use default file types and -to recognize Unix-style C<2E<gt>&1>. - -Expansion of File::Spec::VMS routines, and integration into ExtUtils::MM_VMS. - -Extension of ExtUtils::MM_VMS to handle complex extensions more flexibly. - -Barewords at start of Unix-syntax paths may be treated as text rather than -only as logical names. - -Optional secure translation of several logical names used internally by Perl. - -Miscellaneous bugfixing and porting of new core code to VMS. - -Thanks are gladly extended to the many people who have contributed VMS -patches, testing, and ideas. - -=head2 Win32 - -Perl can now emulate fork() internally, using multiple interpreters running -in different concurrent threads. This support must be enabled at build -time. See L<perlfork> for detailed information. - -When given a pathname that consists only of a drivename, such as C<A:>, -opendir() and stat() now use the current working directory for the drive -rather than the drive root. - -The builtin XSUB functions in the Win32:: namespace are documented. See -L<Win32>. - -$^X now contains the full path name of the running executable. - -A Win32::GetLongPathName() function is provided to complement -Win32::GetFullPathName() and Win32::GetShortPathName(). See L<Win32>. - -POSIX::uname() is supported. - -system(1,...) now returns true process IDs rather than process -handles. kill() accepts any real process id, rather than strictly -return values from system(1,...). - -For better compatibility with Unix, C<kill(0, $pid)> can now be used to -test whether a process exists. - -The C<Shell> module is supported. - -Better support for building Perl under command.com in Windows 95 -has been added. - -Scripts are read in binary mode by default to allow ByteLoader (and -the filter mechanism in general) to work properly. For compatibility, -the DATA filehandle will be set to text mode if a carriage return is -detected at the end of the line containing the __END__ or __DATA__ -token; if not, the DATA filehandle will be left open in binary mode. -Earlier versions always opened the DATA filehandle in text mode. - -The glob() operator is implemented via the C<File::Glob> extension, -which supports glob syntax of the C shell. This increases the flexibility -of the glob() operator, but there may be compatibility issues for -programs that relied on the older globbing syntax. If you want to -preserve compatibility with the older syntax, you might want to run -perl with C<-MFile::DosGlob>. For details and compatibility information, -see L<File::Glob>. - -=head1 Significant bug fixes - -=head2 <HANDLE> on empty files - -With C<$/> set to C<undef>, "slurping" an empty file returns a string of -zero length (instead of C<undef>, as it used to) the first time the -HANDLE is read after C<$/> is set to C<undef>. Further reads yield -C<undef>. - -This means that the following will append "foo" to an empty file (it used -to do nothing): - - perl -0777 -pi -e 's/^/foo/' empty_file - -The behaviour of: - - perl -pi -e 's/^/foo/' empty_file - -is unchanged (it continues to leave the file empty). - -=head2 C<eval '...'> improvements - -Line numbers (as reflected by caller() and most diagnostics) within -C<eval '...'> were often incorrect where here documents were involved. -This has been corrected. - -Lexical lookups for variables appearing in C<eval '...'> within -functions that were themselves called within an C<eval '...'> were -searching the wrong place for lexicals. The lexical search now -correctly ends at the subroutine's block boundary. - -The use of C<return> within C<eval {...}> caused $@ not to be reset -correctly when no exception occurred within the eval. This has -been fixed. - -Parsing of here documents used to be flawed when they appeared as -the replacement expression in C<eval 's/.../.../e'>. This has -been fixed. - -=head2 All compilation errors are true errors - -Some "errors" encountered at compile time were by necessity -generated as warnings followed by eventual termination of the -program. This enabled more such errors to be reported in a -single run, rather than causing a hard stop at the first error -that was encountered. - -The mechanism for reporting such errors has been reimplemented -to queue compile-time errors and report them at the end of the -compilation as true errors rather than as warnings. This fixes -cases where error messages leaked through in the form of warnings -when code was compiled at run time using C<eval STRING>, and -also allows such errors to be reliably trapped using C<eval "...">. - -=head2 Implicitly closed filehandles are safer - -Sometimes implicitly closed filehandles (as when they are localized, -and Perl automatically closes them on exiting the scope) could -inadvertently set $? or $!. This has been corrected. - - -=head2 Behavior of list slices is more consistent - -When taking a slice of a literal list (as opposed to a slice of -an array or hash), Perl used to return an empty list if the -result happened to be composed of all undef values. - -The new behavior is to produce an empty list if (and only if) -the original list was empty. Consider the following example: - - @a = (1,undef,undef,2)[2,1,2]; - -The old behavior would have resulted in @a having no elements. -The new behavior ensures it has three undefined elements. - -Note in particular that the behavior of slices of the following -cases remains unchanged: - - @a = ()[1,2]; - @a = (getpwent)[7,0]; - @a = (anything_returning_empty_list())[2,1,2]; - @a = @b[2,1,2]; - @a = @c{'a','b','c'}; - -See L<perldata>. - -=head2 C<(\$)> prototype and C<$foo{a}> - -A scalar reference prototype now correctly allows a hash or -array element in that slot. - -=head2 C<goto &sub> and AUTOLOAD - -The C<goto &sub> construct works correctly when C<&sub> happens -to be autoloaded. - -=head2 C<-bareword> allowed under C<use integer> - -The autoquoting of barewords preceded by C<-> did not work -in prior versions when the C<integer> pragma was enabled. -This has been fixed. - -=head2 Failures in DESTROY() - -When code in a destructor threw an exception, it went unnoticed -in earlier versions of Perl, unless someone happened to be -looking in $@ just after the point the destructor happened to -run. Such failures are now visible as warnings when warnings are -enabled. - -=head2 Locale bugs fixed - -printf() and sprintf() previously reset the numeric locale -back to the default "C" locale. This has been fixed. - -Numbers formatted according to the local numeric locale -(such as using a decimal comma instead of a decimal dot) caused -"isn't numeric" warnings, even while the operations accessing -those numbers produced correct results. These warnings have been -discontinued. - -=head2 Memory leaks - -The C<eval 'return sub {...}'> construct could sometimes leak -memory. This has been fixed. - -Operations that aren't filehandle constructors used to leak memory -when used on invalid filehandles. This has been fixed. - -Constructs that modified C<@_> could fail to deallocate values -in C<@_> and thus leak memory. This has been corrected. - -=head2 Spurious subroutine stubs after failed subroutine calls - -Perl could sometimes create empty subroutine stubs when a -subroutine was not found in the package. Such cases stopped -later method lookups from progressing into base packages. -This has been corrected. - -=head2 Taint failures under C<-U> - -When running in unsafe mode, taint violations could sometimes -cause silent failures. This has been fixed. - -=head2 END blocks and the C<-c> switch - -Prior versions used to run BEGIN B<and> END blocks when Perl was -run in compile-only mode. Since this is typically not the expected -behavior, END blocks are not executed anymore when the C<-c> switch -is used, or if compilation fails. - -See L</"Support for CHECK blocks"> for how to run things when the compile -phase ends. - -=head2 Potential to leak DATA filehandles - -Using the C<__DATA__> token creates an implicit filehandle to -the file that contains the token. It is the program's -responsibility to close it when it is done reading from it. - -This caveat is now better explained in the documentation. -See L<perldata>. - -=head1 New or Changed Diagnostics - -=over 4 - -=item "%s" variable %s masks earlier declaration in same %s - -(W misc) A "my" or "our" variable has been redeclared in the current scope or statement, -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 "my sub" not yet implemented - -(F) Lexically scoped subroutines are not yet implemented. Don't try that -yet. - -=item "our" variable %s redeclared - -(W misc) You seem to have already declared the same global once before in the -current lexical scope. - -=item '!' allowed only after types %s - -(F) The '!' is allowed in pack() and unpack() only after certain types. -See L<perlfunc/pack>. - -=item / cannot take a count - -(F) You had an unpack template indicating a counted-length string, -but you have also specified an explicit size for the string. -See L<perlfunc/pack>. - -=item / must be followed by a, A or Z - -(F) You had an unpack template indicating a counted-length string, -which must be followed by one of the letters a, A or Z -to indicate what sort of string is to be unpacked. -See L<perlfunc/pack>. - -=item / must be followed by a*, A* or Z* - -(F) You had a pack template indicating a counted-length string, -Currently the only things that can have their length counted are a*, A* or Z*. -See L<perlfunc/pack>. - -=item / must follow a numeric type - -(F) You had an unpack template that contained a '#', -but this did not follow some numeric unpack specification. -See L<perlfunc/pack>. - -=item /%s/: Unrecognized escape \\%c passed through - -(W regexp) You used a backslash-character combination which is not recognized -by Perl. This combination appears in an interpolated variable or a -C<'>-delimited regular expression. The character was understood literally. - -=item /%s/: Unrecognized escape \\%c in character class passed through - -(W regexp) You used a backslash-character combination which is not recognized -by Perl inside character classes. The character was understood literally. - -=item /%s/ should probably be written as "%s" - -(W syntax) You have used a pattern where Perl expected to find a string, -as in the first argument to C<join>. Perl will treat the true -or false result of matching the pattern against $_ as the string, -which is probably not what you had in mind. - -=item %s() called too early to check prototype - -(W prototype) You've called a function that has a prototype before the parser saw a -definition or declaration for it, and Perl could not check that the call -conforms to the prototype. You need to either add an early prototype -declaration for the subroutine in question, or move the subroutine -definition ahead of the call to get proper prototype checking. Alternatively, -if you are certain that you're calling the function correctly, you may put -an ampersand before the name to avoid the warning. See L<perlsub>. - -=item %s argument is not a HASH or ARRAY element - -(F) The argument to exists() must be a hash or array element, such as: - - $foo{$bar} - $ref->{"susie"}[12] - -=item %s argument is not a HASH or ARRAY element or slice - -(F) The argument to delete() must be either a hash or array element, such as: - - $foo{$bar} - $ref->{"susie"}[12] - -or a hash or array slice, such as: - - @foo[$bar, $baz, $xyzzy] - @{$ref->[12]}{"susie", "queue"} - -=item %s argument is not a subroutine name - -(F) The argument to exists() for C<exists &sub> must be a subroutine -name, and not a subroutine call. C<exists &sub()> will generate this error. - -=item %s package attribute may clash with future reserved word: %s - -(W reserved) A lowercase attribute name was used that had a package-specific handler. -That name might have a meaning to Perl itself some day, even though it -doesn't yet. Perhaps you should use a mixed-case attribute name, instead. -See L<attributes>. - -=item (in cleanup) %s - -(W misc) This prefix usually indicates that a DESTROY() method raised -the indicated exception. Since destructors are usually called by -the system at arbitrary points during execution, and often a vast -number of times, the warning is issued only once for any number -of failures that would otherwise result in the same message being -repeated. - -Failure of user callbacks dispatched using the C<G_KEEPERR> flag -could also result in this warning. See L<perlcall/G_KEEPERR>. - -=item <> should be quotes - -(F) You wrote C<< require <file> >> when you should have written -C<require 'file'>. - -=item Attempt to join self - -(F) You tried to join a thread from within itself, which is an -impossible task. You may be joining the wrong thread, or you may -need to move the join() to some other thread. - -=item Bad evalled substitution pattern - -(F) You've used the /e switch to evaluate the replacement for a -substitution, but perl found a syntax error in the code to evaluate, -most likely an unexpected right brace '}'. - -=item Bad realloc() ignored - -(S) An internal routine called realloc() on something that had never been -malloc()ed in the first place. Mandatory, but can be disabled by -setting environment variable C<PERL_BADFREE> to 1. - -=item Bareword found in conditional - -(W bareword) The compiler found a bareword where it expected a conditional, -which often indicates that an || or && was parsed as part of the -last argument of the previous construct, for example: - - open FOO || die; - -It may also indicate a misspelled constant that has been interpreted -as a bareword: - - use constant TYPO => 1; - if (TYOP) { print "foo" } - -The C<strict> pragma is useful in avoiding such errors. - -=item Binary number > 0b11111111111111111111111111111111 non-portable - -(W portable) The binary number you specified is larger than 2**32-1 -(4294967295) and therefore non-portable between systems. See -L<perlport> for more on portability concerns. - -=item Bit vector size > 32 non-portable - -(W portable) Using bit vector sizes larger than 32 is non-portable. - -=item Buffer overflow in prime_env_iter: %s - -(W internal) A warning peculiar to VMS. While Perl was preparing to iterate over -%ENV, it encountered a logical name or symbol definition which was too long, -so it was truncated to the string shown. - -=item Can't check filesystem of script "%s" - -(P) For some reason you can't check the filesystem of the script for nosuid. - -=item Can't declare class for non-scalar %s in "%s" - -(S) Currently, only scalar variables can declared with a specific class -qualifier in a "my" or "our" declaration. The semantics may be extended -for other types of variables in future. - -=item Can't declare %s in "%s" - -(F) Only scalar, array, and hash variables may be declared as "my" or -"our" variables. They must have ordinary identifiers as names. - -=item Can't ignore signal CHLD, forcing to default - -(W signal) Perl has detected that it is being run with the SIGCHLD signal -(sometimes known as SIGCLD) disabled. Since disabling this signal -will interfere with proper determination of exit status of child -processes, Perl has reset the signal to its default value. -This situation typically indicates that the parent program under -which Perl may be running (e.g., cron) is being very careless. - -=item Can't modify non-lvalue subroutine call - -(F) Subroutines meant to be used in lvalue context should be declared as -such, see L<perlsub/"Lvalue subroutines">. - -=item Can't read CRTL environ - -(S) A warning peculiar to VMS. Perl tried to read an element of %ENV -from the CRTL's internal environment array and discovered the array was -missing. You need to figure out where your CRTL misplaced its environ -or define F<PERL_ENV_TABLES> (see L<perlvms>) so that environ is not searched. - -=item Can't remove %s: %s, skipping file - -(S) You requested an inplace edit without creating a backup file. Perl -was unable to remove the original file to replace it with the modified -file. The file was left unmodified. - -=item Can't return %s from lvalue subroutine - -(F) Perl detected an attempt to return illegal lvalues (such -as temporary or readonly values) from a subroutine used as an lvalue. -This is not allowed. - -=item Can't weaken a nonreference - -(F) You attempted to weaken something that was not a reference. Only -references can be weakened. - -=item Character class [:%s:] unknown - -(F) The class in the character class [: :] syntax is unknown. -See L<perlre>. - -=item Character class syntax [%s] belongs inside character classes - -(W unsafe) The character class constructs [: :], [= =], and [. .] go -I<inside> character classes, the [] are part of the construct, -for example: /[012[:alpha:]345]/. Note that [= =] and [. .] -are not currently implemented; they are simply placeholders for -future extensions. - -=item Constant is not %s reference - -(F) A constant value (perhaps declared using the C<use constant> pragma) -is being dereferenced, but it amounts to the wrong type of reference. The -message indicates the type of reference that was expected. This usually -indicates a syntax error in dereferencing the constant value. -See L<perlsub/"Constant Functions"> and L<constant>. - -=item constant(%s): %s - -(F) The parser found inconsistencies either while attempting to define an -overloaded constant, or when trying to find the character name specified -in the C<\N{...}> escape. Perhaps you forgot to load the corresponding -C<overload> or C<charnames> pragma? See L<charnames> and L<overload>. - -=item CORE::%s is not a keyword - -(F) The CORE:: namespace is reserved for Perl keywords. - -=item defined(@array) is deprecated - -(D) defined() is not usually useful on arrays because it checks for an -undefined I<scalar> value. If you want to see if the array is empty, -just use C<if (@array) { # not empty }> for example. - -=item defined(%hash) is deprecated - -(D) defined() is not usually useful on hashes because it checks for an -undefined I<scalar> value. If you want to see if the hash is empty, -just use C<if (%hash) { # not empty }> for example. - -=item Did not produce a valid header - -See Server error. - -=item (Did you mean "local" instead of "our"?) - -(W misc) Remember that "our" does not localize the declared global variable. -You have declared it again in the same lexical scope, which seems superfluous. - -=item Document contains no data - -See Server error. - -=item entering effective %s failed - -(F) While under the C<use filetest> pragma, switching the real and -effective uids or gids failed. - -=item false [] range "%s" in regexp - -(W regexp) A character class range must start and end at a literal character, not -another character class like C<\d> or C<[:alpha:]>. The "-" in your false -range is interpreted as a literal "-". Consider quoting the "-", "\-". -See L<perlre>. - -=item Filehandle %s opened only for output - -(W io) You tried to read from a filehandle opened only for writing. If you -intended it to be a read/write filehandle, you needed to open it with -"+<" or "+>" or "+>>" instead of with "<" or nothing. If -you intended only to read from the file, use "<". See -L<perlfunc/open>. - -=item flock() on closed filehandle %s - -(W closed) The filehandle you're attempting to flock() got itself closed some -time before now. Check your logic flow. flock() operates on filehandles. -Are you attempting to call flock() on a dirhandle by the same name? - -=item Global symbol "%s" requires explicit package name - -(F) You've said "use strict vars", which indicates that all variables -must either be lexically scoped (using "my"), declared beforehand using -"our", or explicitly qualified to say which package the global variable -is in (using "::"). - -=item Hexadecimal number > 0xffffffff non-portable - -(W portable) The hexadecimal number you specified is larger than 2**32-1 -(4294967295) and therefore non-portable between systems. See -L<perlport> for more on portability concerns. - -=item Ill-formed CRTL environ value "%s" - -(W internal) A warning peculiar to VMS. Perl tried to read the CRTL's internal -environ array, and encountered an element without the C<=> delimiter -used to separate keys from values. The element is ignored. - -=item Ill-formed message in prime_env_iter: |%s| - -(W internal) A warning peculiar to VMS. Perl tried to read a logical name -or CLI symbol definition when preparing to iterate over %ENV, and -didn't see the expected delimiter between key and value, so the -line was ignored. - -=item Illegal binary digit %s - -(F) You used a digit other than 0 or 1 in a binary number. - -=item Illegal binary digit %s ignored - -(W digit) You may have tried to use a digit other than 0 or 1 in a binary number. -Interpretation of the binary number stopped before the offending digit. - -=item Illegal number of bits in vec - -(F) The number of bits in vec() (the third argument) must be a power of -two from 1 to 32 (or 64, if your platform supports that). - -=item Integer overflow in %s number - -(W overflow) The hexadecimal, octal or binary number you have specified either -as a literal or as an argument to hex() or oct() is too big for your -architecture, and has been converted to a floating point number. On a -32-bit architecture the largest hexadecimal, octal or binary number -representable without overflow is 0xFFFFFFFF, 037777777777, or -0b11111111111111111111111111111111 respectively. Note that Perl -transparently promotes all numbers to a floating point representation -internally--subject to loss of precision errors in subsequent -operations. - -=item Invalid %s attribute: %s - -The indicated attribute for a subroutine or variable was not recognized -by Perl or by a user-supplied handler. See L<attributes>. - -=item Invalid %s attributes: %s - -The indicated attributes for a subroutine or variable were not recognized -by Perl or by a user-supplied handler. See L<attributes>. - -=item invalid [] range "%s" in regexp - -The offending range is now explicitly displayed. - -=item Invalid separator character %s in attribute list - -(F) Something other than a colon or whitespace was seen between the -elements of an attribute list. If the previous attribute -had a parenthesised parameter list, perhaps that list was terminated -too soon. See L<attributes>. - -=item Invalid separator character %s in subroutine attribute list - -(F) Something other than a colon or whitespace was seen between the -elements of a subroutine attribute list. If the previous attribute -had a parenthesised parameter list, perhaps that list was terminated -too soon. - -=item leaving effective %s failed - -(F) While under the C<use filetest> pragma, switching the real and -effective uids or gids failed. - -=item Lvalue subs returning %s not implemented yet - -(F) Due to limitations in the current implementation, array and hash -values cannot be returned in subroutines used in lvalue context. -See L<perlsub/"Lvalue subroutines">. - -=item Method %s not permitted - -See Server error. - -=item Missing %sbrace%s on \N{} - -(F) Wrong syntax of character name literal C<\N{charname}> within -double-quotish context. - -=item Missing command in piped open - -(W pipe) You used the C<open(FH, "| command")> or C<open(FH, "command |")> -construction, but the command was missing or blank. - -=item Missing name in "my sub" - -(F) The reserved syntax for lexically scoped subroutines requires that they -have a name with which they can be found. - -=item No %s specified for -%c - -(F) The indicated command line switch needs a mandatory argument, but -you haven't specified one. - -=item No package name allowed for variable %s in "our" - -(F) Fully qualified variable names are not allowed in "our" declarations, -because that doesn't make much sense under existing semantics. Such -syntax is reserved for future extensions. - -=item No space allowed after -%c - -(F) The argument to the indicated command line switch must follow immediately -after the switch, without intervening spaces. - -=item no UTC offset information; assuming local time is UTC - -(S) A warning peculiar to VMS. Perl was unable to find the local -timezone offset, so it's assuming that local system time is equivalent -to UTC. If it's not, define the logical name F<SYS$TIMEZONE_DIFFERENTIAL> -to translate to the number of seconds which need to be added to UTC to -get local time. - -=item Octal number > 037777777777 non-portable - -(W portable) The octal number you specified is larger than 2**32-1 (4294967295) -and therefore non-portable between systems. See L<perlport> for more -on portability concerns. - -See also L<perlport> for writing portable code. - -=item panic: del_backref - -(P) Failed an internal consistency check while trying to reset a weak -reference. - -=item panic: kid popen errno read - -(F) forked child returned an incomprehensible message about its errno. - -=item panic: magic_killbackrefs - -(P) Failed an internal consistency check while trying to reset all weak -references to an object. - -=item Parentheses missing around "%s" list - -(W parenthesis) You said something like - - my $foo, $bar = @_; - -when you meant - - my ($foo, $bar) = @_; - -Remember that "my", "our", and "local" bind tighter than comma. - -=item Possible unintended interpolation of %s in string - -(W ambiguous) It used to be that Perl would try to guess whether you -wanted an array interpolated or a literal @. It no longer does this; -arrays are now I<always> interpolated into strings. This means that -if you try something like: - - print "fred@example.com"; - -and the array C<@example> doesn't exist, Perl is going to print -C<fred.com>, which is probably not what you wanted. To get a literal -C<@> sign in a string, put a backslash before it, just as you would -to get a literal C<$> sign. - -=item Possible Y2K bug: %s - -(W y2k) You are concatenating the number 19 with another number, which -could be a potential Year 2000 problem. - -=item pragma "attrs" is deprecated, use "sub NAME : ATTRS" instead - -(W deprecated) You have written something like this: - - sub doit - { - use attrs qw(locked); - } - -You should use the new declaration syntax instead. - - sub doit : locked - { - ... - -The C<use attrs> pragma is now obsolete, and is only provided for -backward-compatibility. See L<perlsub/"Subroutine Attributes">. - - -=item Premature end of script headers - -See Server error. - -=item Repeat count in pack overflows - -(F) You can't specify a repeat count so large that it overflows -your signed integers. See L<perlfunc/pack>. - -=item Repeat count in unpack overflows - -(F) You can't specify a repeat count so large that it overflows -your signed integers. See L<perlfunc/unpack>. - -=item realloc() of freed memory ignored - -(S) An internal routine called realloc() on something that had already -been freed. - -=item Reference is already weak - -(W misc) You have attempted to weaken a reference that is already weak. -Doing so has no effect. - -=item setpgrp can't take arguments - -(F) Your system has the setpgrp() from BSD 4.2, which takes no arguments, -unlike POSIX setpgid(), which takes a process ID and process group ID. - -=item Strange *+?{} on zero-length expression - -(W regexp) You applied a regular expression quantifier in a place where it -makes no sense, such as on a zero-width assertion. -Try putting the quantifier inside the assertion instead. For example, -the way to match "abc" provided that it is followed by three -repetitions of "xyz" is C</abc(?=(?:xyz){3})/>, not C</abc(?=xyz){3}/>. - -=item switching effective %s is not implemented - -(F) While under the C<use filetest> pragma, we cannot switch the -real and effective uids or gids. - -=item This Perl can't reset CRTL environ elements (%s) - -=item This Perl can't set CRTL environ elements (%s=%s) - -(W internal) Warnings peculiar to VMS. You tried to change or delete an element -of the CRTL's internal environ array, but your copy of Perl wasn't -built with a CRTL that contained the setenv() function. You'll need to -rebuild Perl with a CRTL that does, or redefine F<PERL_ENV_TABLES> (see -L<perlvms>) so that the environ array isn't the target of the change to -%ENV which produced the warning. - -=item Too late to run %s block - -(W void) A CHECK or INIT block is being defined during run time proper, -when the opportunity to run them has already passed. Perhaps you are -loading a file with C<require> or C<do> when you should be using -C<use> instead. Or perhaps you should put the C<require> or C<do> -inside a BEGIN block. - -=item Unknown open() mode '%s' - -(F) The second argument of 3-argument open() is not among the list -of valid modes: C<< < >>, C<< > >>, C<<< >> >>>, C<< +< >>, -C<< +> >>, C<<< +>> >>>, C<-|>, C<|->. - -=item Unknown process %x sent message to prime_env_iter: %s - -(P) An error peculiar to VMS. Perl was reading values for %ENV before -iterating over it, and someone else stuck a message in the stream of -data Perl expected. Someone's very confused, or perhaps trying to -subvert Perl's population of %ENV for nefarious purposes. - -=item Unrecognized escape \\%c passed through - -(W misc) You used a backslash-character combination which is not recognized -by Perl. The character was understood literally. - -=item Unterminated attribute parameter in attribute list - -(F) The lexer saw an opening (left) parenthesis character while parsing an -attribute list, but the matching closing (right) parenthesis -character was not found. You may need to add (or remove) a backslash -character to get your parentheses to balance. See L<attributes>. - -=item Unterminated attribute list - -(F) The lexer found something other than a simple identifier at the start -of an attribute, and it wasn't a semicolon or the start of a -block. Perhaps you terminated the parameter list of the previous attribute -too soon. See L<attributes>. - -=item Unterminated attribute parameter in subroutine attribute list - -(F) The lexer saw an opening (left) parenthesis character while parsing a -subroutine attribute list, but the matching closing (right) parenthesis -character was not found. You may need to add (or remove) a backslash -character to get your parentheses to balance. - -=item Unterminated subroutine attribute list - -(F) The lexer found something other than a simple identifier at the start -of a subroutine attribute, and it wasn't a semicolon or the start of a -block. Perhaps you terminated the parameter list of the previous attribute -too soon. - -=item Value of CLI symbol "%s" too long - -(W misc) A warning peculiar to VMS. Perl tried to read the value of an %ENV -element from a CLI symbol table, and found a resultant string longer -than 1024 characters. The return value has been truncated to 1024 -characters. - -=item Version number must be a constant number - -(P) The attempt to translate a C<use Module n.n LIST> statement into -its equivalent C<BEGIN> block found an internal inconsistency with -the version number. - -=back - -=head1 New tests - -=over 4 - -=item lib/attrs - -Compatibility tests for C<sub : attrs> vs the older C<use attrs>. - -=item lib/env - -Tests for new environment scalar capability (e.g., C<use Env qw($BAR);>). - -=item lib/env-array - -Tests for new environment array capability (e.g., C<use Env qw(@PATH);>). - -=item lib/io_const - -IO constants (SEEK_*, _IO*). - -=item lib/io_dir - -Directory-related IO methods (new, read, close, rewind, tied delete). - -=item lib/io_multihomed - -INET sockets with multi-homed hosts. - -=item lib/io_poll - -IO poll(). - -=item lib/io_unix - -UNIX sockets. - -=item op/attrs - -Regression tests for C<my ($x,@y,%z) : attrs> and <sub : attrs>. - -=item op/filetest - -File test operators. - -=item op/lex_assign - -Verify operations that access pad objects (lexicals and temporaries). - -=item op/exists_sub - -Verify C<exists &sub> operations. - -=back - -=head1 Incompatible Changes - -=head2 Perl Source Incompatibilities - -Beware that any new warnings that have been added or old ones -that have been enhanced are B<not> considered incompatible changes. - -Since all new warnings must be explicitly requested via the C<-w> -switch or the C<warnings> pragma, it is ultimately the programmer's -responsibility to ensure that warnings are enabled judiciously. - -=over 4 - -=item CHECK is a new keyword - -All subroutine definitions named CHECK are now special. See -C</"Support for CHECK blocks"> for more information. - -=item Treatment of list slices of undef has changed - -There is a potential incompatibility in the behavior of list slices -that are comprised entirely of undefined values. -See L</"Behavior of list slices is more consistent">. - -=item Format of $English::PERL_VERSION is different - -The English module now sets $PERL_VERSION to $^V (a string value) rather -than C<$]> (a numeric value). This is a potential incompatibility. -Send us a report via perlbug if you are affected by this. - -See L</"Improved Perl version numbering system"> for the reasons for -this change. - -=item Literals of the form C<1.2.3> parse differently - -Previously, numeric literals with more than one dot in them were -interpreted as a floating point number concatenated with one or more -numbers. Such "numbers" are now parsed as strings composed of the -specified ordinals. - -For example, C<print 97.98.99> used to output C<97.9899> in earlier -versions, but now prints C<abc>. - -See L</"Support for strings represented as a vector of ordinals">. - -=item Possibly changed pseudo-random number generator - -Perl programs that depend on reproducing a specific set of pseudo-random -numbers may now produce different output due to improvements made to the -rand() builtin. You can use C<sh Configure -Drandfunc=rand> to obtain -the old behavior. - -See L</"Better pseudo-random number generator">. - -=item Hashing function for hash keys has changed - -Even though Perl hashes are not order preserving, the apparently -random order encountered when iterating on the contents of a hash -is actually determined by the hashing algorithm used. Improvements -in the algorithm may yield a random order that is B<different> from -that of previous versions, especially when iterating on hashes. - -See L</"Better worst-case behavior of hashes"> for additional -information. - -=item C<undef> fails on read only values - -Using the C<undef> operator on a readonly value (such as $1) has -the same effect as assigning C<undef> to the readonly value--it -throws an exception. - -=item Close-on-exec bit may be set on pipe and socket handles - -Pipe and socket handles are also now subject to the close-on-exec -behavior determined by the special variable $^F. - -See L</"More consistent close-on-exec behavior">. - -=item Writing C<"$$1"> to mean C<"${$}1"> is unsupported - -Perl 5.004 deprecated the interpretation of C<$$1> and -similar within interpolated strings to mean C<$$ . "1">, -but still allowed it. - -In Perl 5.6.0 and later, C<"$$1"> always means C<"${$1}">. - -=item delete(), each(), values() and C<\(%h)> - -operate on aliases to values, not copies - -delete(), each(), values() and hashes (e.g. C<\(%h)>) -in a list context return the actual -values in the hash, instead of copies (as they used to in earlier -versions). Typical idioms for using these constructs copy the -returned values, but this can make a significant difference when -creating references to the returned values. Keys in the hash are still -returned as copies when iterating on a hash. - -See also L</"delete(), each(), values() and hash iteration are faster">. - -=item vec(EXPR,OFFSET,BITS) enforces powers-of-two BITS - -vec() generates a run-time error if the BITS argument is not -a valid power-of-two integer. - -=item Text of some diagnostic output has changed - -Most references to internal Perl operations in diagnostics -have been changed to be more descriptive. This may be an -issue for programs that may incorrectly rely on the exact -text of diagnostics for proper functioning. - -=item C<%@> has been removed - -The undocumented special variable C<%@> that used to accumulate -"background" errors (such as those that happen in DESTROY()) -has been removed, because it could potentially result in memory -leaks. - -=item Parenthesized not() behaves like a list operator - -The C<not> operator now falls under the "if it looks like a function, -it behaves like a function" rule. - -As a result, the parenthesized form can be used with C<grep> and C<map>. -The following construct used to be a syntax error before, but it works -as expected now: - - grep not($_), @things; - -On the other hand, using C<not> with a literal list slice may not -work. The following previously allowed construct: - - print not (1,2,3)[0]; - -needs to be written with additional parentheses now: - - print not((1,2,3)[0]); - -The behavior remains unaffected when C<not> is not followed by parentheses. - -=item Semantics of bareword prototype C<(*)> have changed - -The semantics of the bareword prototype C<*> have changed. Perl 5.005 -always coerced simple scalar arguments to a typeglob, which wasn't useful -in situations where the subroutine must distinguish between a simple -scalar and a typeglob. The new behavior is to not coerce bareword -arguments to a typeglob. The value will always be visible as either -a simple scalar or as a reference to a typeglob. - -See L</"More functional bareword prototype (*)">. - -=item Semantics of bit operators may have changed on 64-bit platforms - -If your platform is either natively 64-bit or if Perl has been -configured to used 64-bit integers, i.e., $Config{ivsize} is 8, -there may be a potential incompatibility in the behavior of bitwise -numeric operators (& | ^ ~ << >>). These operators used to strictly -operate on the lower 32 bits of integers in previous versions, but now -operate over the entire native integral width. In particular, note -that unary C<~> will produce different results on platforms that have -different $Config{ivsize}. For portability, be sure to mask off -the excess bits in the result of unary C<~>, e.g., C<~$x & 0xffffffff>. - -See L</"Bit operators support full native integer width">. - -=item More builtins taint their results - -As described in L</"Improved security features">, there may be more -sources of taint in a Perl program. - -To avoid these new tainting behaviors, you can build Perl with the -Configure option C<-Accflags=-DINCOMPLETE_TAINTS>. Beware that the -ensuing perl binary may be insecure. - -=back - -=head2 C Source Incompatibilities - -=over 4 - -=item C<PERL_POLLUTE> - -Release 5.005 grandfathered old global symbol names by providing preprocessor -macros for extension source compatibility. As of release 5.6.0, these -preprocessor definitions are not available by default. You need to explicitly -compile perl with C<-DPERL_POLLUTE> to get these definitions. For -extensions still using the old symbols, this option can be -specified via MakeMaker: - - perl Makefile.PL POLLUTE=1 - -=item C<PERL_IMPLICIT_CONTEXT> - -This new build option provides a set of macros for all API functions -such that an implicit interpreter/thread context argument is passed to -every API function. As a result of this, something like C<sv_setsv(foo,bar)> -amounts to a macro invocation that actually translates to something like -C<Perl_sv_setsv(my_perl,foo,bar)>. While this is generally expected -to not have any significant source compatibility issues, the difference -between a macro and a real function call will need to be considered. - -This means that there B<is> a source compatibility issue as a result of -this if your extensions attempt to use pointers to any of the Perl API -functions. - -Note that the above issue is not relevant to the default build of -Perl, whose interfaces continue to match those of prior versions -(but subject to the other options described here). - -See L<perlguts/"The Perl API"> for detailed information on the -ramifications of building Perl with this option. - - NOTE: PERL_IMPLICIT_CONTEXT is automatically enabled whenever Perl is built - with one of -Dusethreads, -Dusemultiplicity, or both. It is not - intended to be enabled by users at this time. - -=item C<PERL_POLLUTE_MALLOC> - -Enabling Perl's malloc in release 5.005 and earlier caused the namespace of -the system's malloc family of functions to be usurped by the Perl versions, -since by default they used the same names. Besides causing problems on -platforms that do not allow these functions to be cleanly replaced, this -also meant that the system versions could not be called in programs that -used Perl's malloc. Previous versions of Perl have allowed this behaviour -to be suppressed with the HIDEMYMALLOC and EMBEDMYMALLOC preprocessor -definitions. - -As of release 5.6.0, Perl's malloc family of functions have default names -distinct from the system versions. You need to explicitly compile perl with -C<-DPERL_POLLUTE_MALLOC> to get the older behaviour. HIDEMYMALLOC -and EMBEDMYMALLOC have no effect, since the behaviour they enabled is now -the default. - -Note that these functions do B<not> constitute Perl's memory allocation API. -See L<perlguts/"Memory Allocation"> for further information about that. - -=back - -=head2 Compatible C Source API Changes - -=over 4 - -=item C<PATCHLEVEL> is now C<PERL_VERSION> - -The cpp macros C<PERL_REVISION>, C<PERL_VERSION>, and C<PERL_SUBVERSION> -are now available by default from perl.h, and reflect the base revision, -patchlevel, and subversion respectively. C<PERL_REVISION> had no -prior equivalent, while C<PERL_VERSION> and C<PERL_SUBVERSION> were -previously available as C<PATCHLEVEL> and C<SUBVERSION>. - -The new names cause less pollution of the B<cpp> namespace and reflect what -the numbers have come to stand for in common practice. For compatibility, -the old names are still supported when F<patchlevel.h> is explicitly -included (as required before), so there is no source incompatibility -from the change. - -=back - -=head2 Binary Incompatibilities - -In general, the default build of this release is expected to be binary -compatible for extensions built with the 5.005 release or its maintenance -versions. However, specific platforms may have broken binary compatibility -due to changes in the defaults used in hints files. Therefore, please be -sure to always check the platform-specific README files for any notes to -the contrary. - -The usethreads or usemultiplicity builds are B<not> binary compatible -with the corresponding builds in 5.005. - -On platforms that require an explicit list of exports (AIX, OS/2 and Windows, -among others), purely internal symbols such as parser functions and the -run time opcodes are not exported by default. Perl 5.005 used to export -all functions irrespective of whether they were considered part of the -public API or not. - -For the full list of public API functions, see L<perlapi>. - -=head1 Known Problems - -=head2 Localizing a tied hash element may leak memory - -As of the 5.6.1 release, there is a known leak when code such as this -is executed: - - use Tie::Hash; - tie my %tie_hash => 'Tie::StdHash'; - - ... - - local($tie_hash{Foo}) = 1; # leaks - -=head2 Known test failures - -=over - -=item 64-bit builds - -Subtest #15 of lib/b.t may fail under 64-bit builds on platforms such -as HP-UX PA64 and Linux IA64. The issue is still being investigated. - -The lib/io_multihomed test may hang in HP-UX if Perl has been -configured to be 64-bit. Because other 64-bit platforms do not -hang in this test, HP-UX is suspect. All other tests pass -in 64-bit HP-UX. The test attempts to create and connect to -"multihomed" sockets (sockets which have multiple IP addresses). - -Note that 64-bit support is still experimental. - -=item Failure of Thread tests - -The subtests 19 and 20 of lib/thr5005.t test are known to fail due to -fundamental problems in the 5.005 threading implementation. These are -not new failures--Perl 5.005_0x has the same bugs, but didn't have these -tests. (Note that support for 5.005-style threading remains experimental.) - -=item NEXTSTEP 3.3 POSIX test failure - -In NEXTSTEP 3.3p2 the implementation of the strftime(3) in the -operating system libraries is buggy: the %j format numbers the days of -a month starting from zero, which, while being logical to programmers, -will cause the subtests 19 to 27 of the lib/posix test may fail. - -=item Tru64 (aka Digital UNIX, aka DEC OSF/1) lib/sdbm test failure with gcc - -If compiled with gcc 2.95 the lib/sdbm test will fail (dump core). -The cure is to use the vendor cc, it comes with the operating system -and produces good code. - -=back - -=head2 EBCDIC platforms not fully supported - -In earlier releases of Perl, EBCDIC environments like OS390 (also -known as Open Edition MVS) and VM-ESA were supported. Due to changes -required by the UTF-8 (Unicode) support, the EBCDIC platforms are not -supported in Perl 5.6.0. - -The 5.6.1 release improves support for EBCDIC platforms, but they -are not fully supported yet. - -=head2 UNICOS/mk CC failures during Configure run - -In UNICOS/mk the following errors may appear during the Configure run: - - Guessing which symbols your C compiler and preprocessor define... - CC-20 cc: ERROR File = try.c, Line = 3 - ... - bad switch yylook 79bad switch yylook 79bad switch yylook 79bad switch yylook 79#ifdef A29K - ... - 4 errors detected in the compilation of "try.c". - -The culprit is the broken awk of UNICOS/mk. The effect is fortunately -rather mild: Perl itself is not adversely affected by the error, only -the h2ph utility coming with Perl, and that is rather rarely needed -these days. - -=head2 Arrow operator and arrays - -When the left argument to the arrow operator C<< -> >> is an array, or -the C<scalar> operator operating on an array, the result of the -operation must be considered erroneous. For example: - - @x->[2] - scalar(@x)->[2] - -These expressions will get run-time errors in some future release of -Perl. - -=head2 Experimental features - -As discussed above, many features are still experimental. Interfaces and -implementation of these features are subject to change, and in extreme cases, -even subject to removal in some future release of Perl. These features -include the following: - -=over 4 - -=item Threads - -=item Unicode - -=item 64-bit support - -=item Lvalue subroutines - -=item Weak references - -=item The pseudo-hash data type - -=item The Compiler suite - -=item Internal implementation of file globbing - -=item The DB module - -=item The regular expression code constructs: - -C<(?{ code })> and C<(??{ code })> - -=back - -=head1 Obsolete Diagnostics - -=over 4 - -=item Character class syntax [: :] is reserved for future extensions - -(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 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. Because 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 nonstandard names, -or it may indicate that a logical name table has been corrupted. - -=item In string, @%s now must be written as \@%s - -The description of this error used to say: - - (Someday it will simply assume that an unbackslashed @ - interpolates an array.) - -That day has come, and this fatal error has been removed. It has been -replaced by a non-fatal warning instead. -See L</Arrays now always interpolate into double-quoted strings> for -details. - -=item Probable precedence problem on %s - -(W) The compiler found a bareword where it expected a conditional, -which often indicates that an || or && was parsed as part of the -last argument of the previous construct, for example: - - open FOO || die; - -=item regexp too big - -(F) The current implementation of regular expressions uses shorts as -address offsets within a string. Unfortunately this means that if -the regular expression compiles to longer than 32767, it'll blow up. -Usually when you want a regular expression this big, there is a better -way to do it with multiple statements. See L<perlre>. - -=item Use of "$$<digit>" to mean "${$}<digit>" is deprecated - -(D) Perl versions before 5.004 misinterpreted any type marker followed -by "$" and a digit. For example, "$$0" was incorrectly taken to mean -"${$}0" instead of "${$0}". This bug is (mostly) fixed in Perl 5.004. - -However, the developers of Perl 5.004 could not fix this bug completely, -because at least two widely-used modules depend on the old meaning of -"$$0" in a string. So Perl 5.004 still interprets "$$<digit>" in the -old (broken) way inside strings; but it generates this message as a -warning. And in Perl 5.005, this special treatment will cease. - -=back - -=head1 Reporting Bugs - -If you find what you think is a bug, you might check the -articles recently posted to the comp.lang.perl.misc newsgroup. -There may also be information at http://www.perl.com/, the Perl -Home Page. - -If you believe you have an unreported bug, please run the B<perlbug> -program included with your release. Be sure to 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.org 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. - -The F<README> file for general stuff. - -The F<Artistic> and F<Copying> files for copyright information. - -=head1 HISTORY - -Written by Gurusamy Sarathy <F<gsar@ActiveState.com>>, with many -contributions from The Perl Porters. - -Send omissions or corrections to <F<perlbug@perl.org>>. - -=cut |
