=head1 NAME
-perldelta - what's new for perl5.006 (as of 5.005_54)
+perldelta - what's new for perl v5.6 (as of v5.005_58)
=head1 DESCRIPTION
+This is an unsupported alpha release, meant for intrepid Perl developers
+only. The included sources may not even build correctly on some platforms.
+Subscribing to perl5-porters is the best way to monitor and contribute
+to the progress of development releases (see www.perl.org for info).
+
This document describes differences between the 5.005 release and this one.
=head1 Incompatible Changes
=head2 Perl Source Incompatibilities
-None known at this time.
+TODO
=head2 C Source Incompatibilities
=item C<PERL_POLLUTE>
Release 5.005 grandfathered old global symbol names by providing preprocessor
-macros for extension source compatibility. As of release 5.006, these
+macros for extension source compatibility. As of release 5.6, these
preprocessor definitions are not available by default. You need to explicitly
-compile perl with C<-DPERL_POLLUTE> in order to get these definitions.
+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).
+
+For testing purposes, the 5.005_58 release automatically enables
+PERL_IMPLICIT_CONTEXT whenever Perl is built with -Dusethreads or
+-Dusemultiplicity.
+
+See L<perlguts/"The Perl API"> for detailed information on the
+ramifications of building Perl using this option.
+
+=item C<PERL_POLLUTE_MALLOC>
+
+Enabling Perl's malloc in release 5.005 and earlier caused
+the namespace of system versions of the 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, 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.
=item C<PL_na> and C<dTHR> Issues
The C<PL_na> global is now thread local, so a C<dTHR> declaration is needed
-in the scope in which it appears. XSUBs should handle this automatically,
+in the scope in which the global appears. XSUBs should handle this automatically,
but if you have used C<PL_na> in support functions, you either need to
change the C<PL_na> to a local variable (which is recommended), or put in
a C<dTHR>.
=back
+=head2 Compatible C Source API Changes
+
+=over
+
+=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
-This release is not binary compatible with the 5.005 release and its
-maintenance versions.
+The default build of this release can be made binary compatible with the
+5.005 release or its maintenance versions. Add -DPERL_BINCOMPAT_5005
+to ccflags in config.sh to achieve this. See INSTALL for further
+information about adding build flags to config.sh.
+
+The usethreads or usemultiplicity builds are B<not> binary compatible
+with the corresponding builds in 5.005.
=head1 Core Changes
+=head2 Unicode and UTF-8 support
+
+Perl can optionally use UTF-8 as its internal representation for character
+strings. The C<use utf8> pragma enables this support in the current lexical
+scope. See L<utf8> for more information.
+
+=head2 Lexically scoped warning categories
+
+You can now control the granularity of warnings emitted by perl at a finer
+level using the C<use warning> pragma. See L<warning> and L<perllexwarn>
+for details.
+
+=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");
+ $answer = 0b101010;
+ printf "The answer is: %b\n", oct("0b101010");
+
+=head2 syswrite() ease-of-use
The length argument of C<syswrite()> is now optional.
+=head2 64-bit support
+
Better 64-bit support -- but full support still a distant goal. One
must Configure with -Duse64bits to get Configure to probe for the
extent of 64-bit support. Depending on the platform (hints file) more
or less 64-awareness becomes available. As of 5.005_54 at least
somewhat 64-bit aware platforms are HP-UX 11 or better, Solaris 2.6 or
better, IRIX 6.2 or better. Naturally 64-bit platforms like Digital
-UNIX and UNICOS also have 64-bit support.
+Unix and UNICOS also have 64-bit support.
+
+=head2 Better syntax checks on parenthesized unary operators
+
+Expressions such as:
+
+ print defined(&foo,&bar,&baz);
+ print uc("foo","bar","baz");
+ undef($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 POSIX character class syntax [: :] supported
+
+For example to match alphabetic characters use /[[:alpha:]]/.
+See L<perlre> for details.
+
+=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 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 $^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 is guaranteed not to
+acquire special meaning in any future version of Perl.
+
+=head1 Significant bug fixes
+
+=head2 E<lt>HANDLEE<gt> 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. 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 when 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.
+
+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 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.
+
+=head2 Better diagnostics on meaningless filehandle operations
+
+Constructs such as C<open(E<lt>FHE<gt>)> and C<close(E<lt>FHE<gt>)>
+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).
=head1 Supported Platforms
+=over 4
+
+=item *
+
VM/ESA is now supported.
-Siemens BS200 is now supported.
+=item *
+
+Siemens BS2000 is now supported under the POSIX Shell.
+
+=item *
+
+The Mach CThreads (NEXTSTEP, OPENSTEP) are now supported by the Thread
+extension.
+
+=item *
+
+GNU/Hurd is now supported.
+
+=item *
+
+Rhapsody is now supported.
+
+=item *
-The Mach CThreads (NeXTstep) are now supported by the Thread extension.
+EPOC is is now supported (on Psion 5).
+
+=back
=head1 New tests
=item op/io_const
IO constants (SEEK_*, _IO*).
-
+
=item op/io_dir
Directory-related IO methods (new, read, close, rewind, tied delete).
=item op/lex_assign
-Guard against lexicals leaking (internal stuff).
+Verify operations that access pad objects (lexicals and temporaries).
=back
=head2 Modules
-Dumpvalue module provides screen dumps of Perl data.
+=over 4
+
+=item ByteLoader
+
+The ByteLoader is a dedication extension to generate and run
+Perl bytecode. See L<ByteLoader>.
+
+=item B
+
+The Perl Compiler suite has been extensively reworked for this
+release.
+
+=item Devel::DProf
+
+Devel::DProf, a Perl source code profiler has been added.
+
+=item Dumpvalue
+
+Added Dumpvalue module provides screen dumps of Perl data.
+
+=item Benchmark
+
+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)".
+
+=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 Fcntl
+
+More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for
+large (more than 4G) file access (64-bit support is not yet
+working, though, so no need to get overly excited), Free/Net/OpenBSD
+locking behaviour flags F_FLOCK, F_POSIX, Linux F_SHLCK, and
+O_ACCMODE: the mask of O_RDONLY, O_WRONLY, and O_RDWR.
+
+=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 Math::BigInt
+
+The logical operations C<E<lt>E<lt>>, C<E<gt>E<gt>>, 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)).
+
+=item Math::Trig
+
+A little bit of radial trigonometry (cylindrical and spherical),
+radial coordinate conversions, and the great circle distance were added.
+
+=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.
+
+=item Time::Local
+
+The timelocal() and timegm() functions used to silently return bogus
+results when the date exceeded 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.
+
+=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
-Lexical warnings pragma, "use warning;", to control optional warnings.
+C<use utf8> to enable UTF-8 and Unicode support.
+
+C<use caller 'encoding'> allows modules to inherit pragmatic attributes
+from the caller's context. C<encoding> is currently the only supported
+attribute.
-Filetest pragma, to control the behaviour of filetests (C<-r> C<-w> ...).
+Lexical warnings pragma, C<use warning;>, to control optional warnings.
+
+C<use filetest> to control the behaviour of filetests (C<-r> C<-w> ...).
Currently only one subpragma implemented, "use filetest 'access';",
-that enables the use of access(2) or equivalent to check the
+that enables the use of 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, while access(2) knows better.
-
-Todo.
+in filesystems where there are ACLs (access control lists): the
+stat(2) might lie, but access(2) knows better.
=head1 Utility Changes
=head1 Documentation Changes
-perlopentut, tutorial on opening things in Perl, was added.
+=over 4
+
+=item perlopentut.pod
+
+A tutorial on using open() effectively.
+
+=item perlreftut.pod
-perlreftut, tutorial on references, was added.
+A tutorial that introduces the essentials of references.
+
+=item perltootc.pod
+
+A tutorial on managing class data for object modules.
+
+=back
=head1 New Diagnostics
=item /%s/: Unrecognized escape \\%c passed through
(W) You used a backslash-character combination which is not recognized
-by Perl. This combination appears in an interpolated variable or a
+by Perl. This combination appears in an interpolated variable or a
C<'>-delimited regular expression.
-=item Unrecognized escape \\%c passed through
+=item Filehandle %s opened only for output
-(W) You used a backslash-character combination which is not recognized
-by Perl.
+(W) 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
+"+E<lt>" or "+E<gt>" or "+E<gt>E<gt>" instead of with "E<lt>" or nothing. If
+you intended only to read from the file, use "E<lt>". See
+L<perlfunc/open>.
=item Missing command in piped open
(W) You used the C<open(FH, "| command")> or C<open(FH, "command |")>
construction, but the command was missing or blank.
+=item Unrecognized escape \\%c passed through
+
+(W) You used a backslash-character combination which is not recognized
+by Perl.
+
+=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.
+
=head1 Obsolete Diagnostics
Todo.
=head1 Configuration Changes
+=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, http://www.socks.nec.com/
+
=head1 BUGS
If you find what you think is a bug, you might check the headers of
-recently posted articles in the comp.lang.perl.misc newsgroup.
+articles recently posted to the comp.lang.perl.misc newsgroup.
There may also be information at http://www.perl.com/perl/, the Perl
Home Page.
If you believe you have an unreported bug, please run the B<perlbug>
-program included with your release. Make sure you trim your bug down
+program included with your release. Make 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 <F<perlbug@perl.com>> to be
+output of C<perl -V>, will be sent off to perlbug@perl.com to be
analysed by the Perl porting team.
=head1 SEE ALSO
projects / p5sagit/p5-mst-13.2.git / blobdiff