diff options
Diffstat (limited to 'Master/tlpkg/tlperl/lib/pods/perl593delta.pod')
-rwxr-xr-x | Master/tlpkg/tlperl/lib/pods/perl593delta.pod | 549 |
1 files changed, 549 insertions, 0 deletions
diff --git a/Master/tlpkg/tlperl/lib/pods/perl593delta.pod b/Master/tlpkg/tlperl/lib/pods/perl593delta.pod new file mode 100755 index 00000000000..80f8cb925fb --- /dev/null +++ b/Master/tlpkg/tlperl/lib/pods/perl593delta.pod @@ -0,0 +1,549 @@ +=head1 NAME + +perl593delta - what is new for perl v5.9.3 + +=head1 DESCRIPTION + +This document describes differences between the 5.9.2 and the 5.9.3 +development releases. See L<perl590delta>, L<perl591delta> and +L<perl592delta> for the differences between 5.8.0 and 5.9.2. + +=head1 Incompatible Changes + +=head2 Parsing of C<-f _> + +The identifier C<_> is now forced to be a bareword after a filetest +operator. This solves a number of misparsing issues when a global C<_> +subroutine is defined. + +=head2 C<mkdir()> + +C<mkdir()> without arguments now defaults to C<$_>. + +=head2 Magic goto and eval + +The construct C<eval { goto &foo }> is now disallowed. (Note that the +similar construct, but with C<eval("")> instead, was already forbidden.) + +=head2 C<$#> has been removed + +The deprecated C<$#> variable (output format for numbers) has been +removed. A new warning, C<$# is no longer supported>, has been added. + +=head2 C<:unique> + +The C<:unique> attribute has been made a no-op, since its current +implementation was fundamentally flawed and not threadsafe. + +=head2 Scoping of the C<sort> pragma + +The C<sort> pragma is now lexically scoped. Its effect used to be global. + +=head1 Core Enhancements + +=head2 The C<feature> pragma + +The C<feature> pragma is used to enable new syntax that would break Perl's +backwards-compatibility with older releases of the language. It's a lexical +pragma, like C<strict> or C<warnings>. + +Currently the following new features are available: C<switch> (adds a +switch statement), C<~~> (adds a Perl 6-like smart match operator), C<say> +(adds a C<say> built-in function), and C<err> (adds an C<err> keyword). +Those features are described below. + +Note that C<err> low-precedence defined-or operator used to be enabled by +default (although as a weak keyword, meaning that any function would +override it). It's now only recognized when explicitly turned on (and is +then a regular keyword). + +Those features, and the C<feature> pragma itself, have been contributed by +Robin Houston. + +=head2 Switch and Smart Match operator + +Perl 5 now has a switch statement. It's available when C<use feature +'switch'> is in effect. This feature introduces three new keywords, +C<given>, C<when>, and C<default>: + + given ($foo) { + when (/^abc/) { $abc = 1; } + when (/^def/) { $def = 1; } + when (/^xyz/) { $xyz = 1; } + default { $nothing = 1; } + } + +A more complete description of how Perl matches the switch variable +against the C<when> conditions is given in L<perlsyn/"Switch statements">. + +This kind of match is called I<smart match>, and it's also possible to use +it outside of switch statements, via the new C<~~> operator (enabled via +the C<use feature '~~'> directive). See L<perlsyn/"Smart matching in +detail">. + +=head2 C<say()> + +say() is a new built-in, only available when C<use feature 'say'> is in +effect, that is similar to print(), but that implicitly appends a newline +to the printed string. See L<perlfunc/say>. + +=head2 C<CLONE_SKIP()> + +Perl has now support for the C<CLONE_SKIP> special subroutine. Like +C<CLONE>, C<CLONE_SKIP> is called once per package; however, it is called +just before cloning starts, and in the context of the parent thread. If it +returns a true value, then no objects of that class will be cloned. See +L<perlmod> for details. (Contributed by Dave Mitchell.) + +=head2 C<${^CHILD_ERROR_NATIVE}> + +A new internal variable, C<${^CHILD_ERROR_NATIVE}>, gives the native +status returned by the last pipe close, backtick command, successful call +to wait() or waitpid(), or from the system() operator. See L<perlrun> for +details. (Contributed by Gisle Aas.) + +=head2 Assertions + +The support for assertions, introduced in perl 5.9.0, has been improved. +The syntax for the C<-A> command-line switch has changed; it now accepts +an optional module name, defaulting to C<assertions::activate>. See +L<assertions> and L<perlrun>. (Contributed by Salvador Fandiño García.) + +=head2 Unicode Character Database 4.1.0 + +The copy of the Unicode Character Database included in Perl 5.9 has +been updated to 4.1.0. + +=head2 C<no VERSION> + +You can now use C<no> followed by a version number to specify that you +want to use a version of perl older than the specified one. + +=head2 Recursive sort subs + +You can now use recursive subroutines with sort(), thanks to Robin Houston. + +=head2 Effect of pragmas in eval + +The compile-time value of the C<%^H> hint variable can now propagate into +eval("")uated code. This makes it more useful to implement lexical +pragmas. + +As a side-effect of this, the overloaded-ness of constants now propagates +into eval(""). + +=head2 New B<-E> command-line switch + +B<-E> is equivalent to B<-e>, but it implicitly enables all +optional features (like C<use feature ":5.10">). + +=head2 C<chdir>, C<chmod> and C<chown> on filehandles + +C<chdir>, C<chmod> and C<chown> can now work on filehandles as well as +filenames, if the system supports respectively C<fchdir>, C<fchmod> and +C<fchown>, thanks to a patch provided by Gisle Aas. + +=head2 OS groups + +C<$(> and C<$)> now return groups in the order where the OS returns them, +thanks to Gisle Aas. This wasn't previously the case. + +=head1 Modules and Pragmata + +=head2 New Core Modules + +=over 4 + +=item * + +A new pragma, C<feature>, has been added; see above in L</"Core +Enhancements">. + +=item * + +C<assertions::compat>, also available on CPAN, allows the use of assertions on +perl versions prior to 5.9.0 (that is the first one to natively support +them). + +=item * + +C<Math::BigInt::FastCalc> is an XS-enabled, and thus faster, version of +C<Math::BigInt::Calc>. + +=item * + +C<Compress::Zlib> is an interface to the zlib compression library. It +comes with a bundled version of zlib, so having a working zlib is not a +prerequisite to install it. It's used by C<Archive::Tar> (see below). + +=item * + +C<IO::Zlib> is an C<IO::>-style interface to C<Compress::Zlib>. + +=item * + +C<Archive::Tar> is a module to manipulate C<tar> archives. + +=item * + +C<Digest::SHA> is a module used to calculate many types of SHA digests, +has been included for SHA support in the CPAN module. + +=item * + +C<ExtUtils::CBuilder> and C<ExtUtils::ParseXS> have been added. + +=back + +=head1 Utility Changes + +=head2 C<ptar> + +C<ptar> is a pure perl implementation of C<tar>, that comes with +C<Archive::Tar>. + +=head2 C<ptardiff> + +C<ptardiff> is a small script used to generate a diff between the contents +of a tar archive and a directory tree. Like C<ptar>, it comes with +C<Archive::Tar>. + +=head2 C<shasum> + +This command-line utility, used to print or to check SHA digests, comes +with the new C<Digest::SHA> module. + +=head2 C<h2xs> enhancements + +C<h2xs> implements a new option C<--use-xsloader> to force use of +C<XSLoader> even in backwards compatible modules. + +The handling of authors' names that had apostrophes has been fixed. + +Any enums with negative values are now skipped. + +=head2 C<perlivp> enhancements + +C<perlivp> no longer checks for F<*.ph> files by default. Use the new C<-a> +option to run I<all> tests. + +=head1 Documentation + +=head2 Perl Glossary + +The L<perlglossary> manpage is a glossary of terms used in the Perl +documentation, technical and otherwise, kindly provided by O'Reilly Media, +Inc. + +L<perltodo> now lists a rough roadmap to Perl 5.10. + +=head1 Performance Enhancements + +=head2 XS-assisted SWASHGET + +Some pure-perl code that perl was using to retrieve Unicode properties and +transliteration mappings has been reimplemented in XS. + +=head2 Constant subroutines + +The interpreter internals now support a far more memory efficient form of +inlineable constants. Storing a reference to a constant value in a symbol +table is equivalent to a full typeglob referencing a constant subroutine, +but using about 400 bytes less memory. This proxy constant subroutine is +automatically upgraded to a real typeglob with subroutine if necessary. +The approach taken is analogous to the existing space optimisation for +subroutine stub declarations, which are stored as plain scalars in place +of the full typeglob. + +Several of the core modules have been converted to use this feature for +their system dependent constants - as a result C<use POSIX;> now takes about +200K less memory. + +=head2 C<PERL_DONT_CREATE_GVSV> + +The new compilation flag C<PERL_DONT_CREATE_GVSV>, introduced as an option +in perl 5.8.8, is turned on by default in perl 5.9.3. It prevents perl +from creating an empty scalar with every new typeglob. See L<perl589delta> +for details. + +=head2 Weak references are cheaper + +Weak reference creation is now I<O(1)> rather than I<O(n)>, courtesy of +Nicholas Clark. Weak reference deletion remains I<O(n)>, but if deletion only +happens at program exit, it may be skipped completely. + +=head2 sort() enhancements + +Salvador Fandiño provided improvements to reduce the memory usage of C<sort> +and to speed up some cases. + +=head1 Installation and Configuration Improvements + +=head2 Compilation improvements + +Parallel makes should work properly now, although there may still be problems +if C<make test> is instructed to run in parallel. + +Building with Borland's compilers on Win32 should work more smoothly. In +particular Steve Hay has worked to side step many warnings emitted by their +compilers and at least one C compiler internal error. + +Perl extensions on Windows now can be statically built into the Perl DLL, +thanks to a work by Vadim Konovalov. + +=head2 New Or Improved Platforms + +Perl is being ported to Symbian OS. See L<perlsymbian> for more +information. + +The VMS port has been improved. See L<perlvms>. + +DynaLoader::dl_unload_file() now works on Windows. + +Portability of Perl on various recent compilers on Windows has been +improved (Borland C++, Visual C++ 7.0). + +=head2 New probes + +C<Configure> will now detect C<clearenv> and C<unsetenv>, thanks to a +patch from Alan Burlison. It will also probe for C<futimes> (and use it +internally if available), and whether C<sprintf> correctly returns the +length of the formatted string. + +=head2 Module auxiliary files + +README files and changelogs for CPAN modules bundled with perl are no +longer installed. + +=head1 Selected Bug Fixes + +=head2 C<defined $$x> + +C<use strict "refs"> was ignoring taking a hard reference in an argument +to defined(), as in : + + use strict "refs"; + my $x = "foo"; + if (defined $$x) {...} + +This now correctly produces the run-time error C<Can't use string as a +SCALAR ref while "strict refs" in use>. (However, C<defined @$foo> and +C<defined %$foo> are still allowed. Those constructs are discouraged +anyway.) + +=head2 Calling CORE::require() + +CORE::require() and CORE::do() were always parsed as require() and do() +when they were overridden. This is now fixed. + +=head2 Subscripts of slices + +You can now use a non-arrowed form for chained subscripts after a list +slice, like in: + + ({foo => "bar"})[0]{foo} + +This used to be a syntax error; a C<< -> >> was required. + +=head2 Remove over-optimisation + +Perl 5.9.2 introduced a change so that assignments of C<undef> to a +scalar, or of an empty list to an array or a hash, were optimised out. As +this could cause problems when C<goto> jumps were involved, this change +was backed out. + +=head2 sprintf() fixes + +Using the sprintf() function with some formats could lead to a buffer +overflow in some specific cases. This has been fixed, along with several +other bugs, notably in bounds checking. + +In related fixes, it was possible for badly written code that did not follow +the documentation of C<Sys::Syslog> to have formatting vulnerabilities. +C<Sys::Syslog> has been changed to protect people from poor quality third +party code. + +=head2 no warnings 'category' works correctly with -w + +Previously when running with warnings enabled globally via C<-w>, selective +disabling of specific warning categories would actually turn off all warnings. +This is now fixed; now C<no warnings 'io';> will only turn off warnings in the +C<io> class. Previously it would erroneously turn off all warnings. + +=head2 Smaller fixes + +=over 4 + +=item * + +C<FindBin> now works better with directories where access rights are more +restrictive than usual. + +=item * + +Several memory leaks in ithreads were closed. Also, ithreads were made +less memory-intensive. + +=item * + +Trailing spaces are now trimmed from C<$!> and C<$^E>. + +=item * + +Operations that require perl to read a process' list of groups, such as reads +of C<$(> and C<$)>, now dynamically allocate memory rather than using a +fixed sized array. The fixed size array could cause C stack exhaustion on +systems configured to use large numbers of groups. + +=item * + +C<PerlIO::scalar> now works better with non-default C<$/> settings. + +=item * + +The C<x> repetition operator is now able to operate on C<qw//> lists. This +used to raise a syntax error. + +=item * + +The debugger now traces correctly execution in eval("")uated code that +contains #line directives. + +=item * + +The value of the C<open> pragma is no longer ignored for three-argument +opens. + +=item * + +Perl will now use the C library calls C<unsetenv> and C<clearenv> if present +to delete keys from C<%ENV> and delete C<%ENV> entirely, thanks to a patch +from Alan Burlison. + +=back + +=head2 More Unicode Fixes + +=over 4 + +=item * + +chr() on a negative value now gives C<\x{FFFD}>, the Unicode replacement +character, unless when the C<bytes> pragma is in effect, where the low +eight bytes of the value are used. + +=item * + +Some case insensitive matches between UTF-8 encoded data and 8 bit regexps, +and vice versa, could give malformed character warnings. These have been +fixed by Dave Mitchell and Yves Orton. + +=item * + +C<lcfirst> and C<ucfirst> could corrupt the string for certain cases where +the length UTF-8 encoding of the string in lower case, upper case or title +case differed. This was fixed by Nicholas Clark. + +=back + +=head1 New or Changed Diagnostics + +=head2 Attempt to set length of freed array + +This is a new warning, produced in situations like the following one: + + $r = do {my @a; \$#a}; + $$r = 503; + +=head2 Non-string passed as bitmask + +This is a new warning, produced when number has been passed as a argument to +select(), instead of a bitmask. + + # Wrong, will now warn + $rin = fileno(STDIN); + ($nfound,$timeleft) = select($rout=$rin, undef, undef, $timeout); + + # Should be + $rin = ''; + vec($rin,fileno(STDIN),1) = 1; + ($nfound,$timeleft) = select($rout=$rin, undef, undef, $timeout); + +=head2 Search pattern not terminated or ternary operator parsed as search pattern + +This syntax error indicates that the lexer couldn't find the final +delimiter of a C<?PATTERN?> construct. Mentioning the ternary operator in +this error message makes syntax diagnostic easier. + +=head2 "%s" variable %s masks earlier declaration + +This warning is now emitted in more consistent cases; in short, when one +of the declarations involved is a C<my> variable: + + my $x; my $x; # warns + my $x; our $x; # warns + our $x; my $x; # warns + +On the other hand, the following: + + our $x; our $x; + +now gives a C<"our" variable %s redeclared> warning. + +=head2 readdir()/closedir()/etc. attempted on invalid dirhandle + +These new warnings are now emitted when a dirhandle is used but is +either closed or not really a dirhandle. + +=head1 Changed Internals + +In general, the source code of perl has been refactored, tied up, and +optimized in many places. Also, memory management and allocation has been +improved in a couple of points. + +Andy Lester supplied many improvements to determine which function +parameters and local variables could actually be declared C<const> to the C +compiler. Steve Peters provided new C<*_set> macros and reworked the core to +use these rather than assigning to macros in LVALUE context. + +Dave Mitchell improved the lexer debugging output under C<-DT>. + +A new file, F<mathoms.c>, has been added. It contains functions that are +no longer used in the perl core, but that remain available for binary or +source compatibility reasons. However, those functions will not be +compiled in if you add C<-DNO_MATHOMS> in the compiler flags. + +The C<AvFLAGS> macro has been removed. + +The C<av_*()> functions, used to manipulate arrays, no longer accept null +C<AV*> parameters. + +=head2 B:: modules inheritance changed + +The inheritance hierarchy of C<B::> modules has changed; C<B::NV> now +inherits from C<B::SV> (it used to inherit from C<B::IV>). + +=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 and the perl +bug database at http://bugs.perl.org/ . There may also be +information at http://www.perl.org/ , 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. + +=cut |