3 perldelta - what's new for perl5.006 (as of 5.005_56)
7 This document describes differences between the 5.005 release and this one.
9 =head1 Incompatible Changes
11 =head2 Perl Source Incompatibilities
13 None known at this time.
15 =head2 C Source Incompatibilities
21 Release 5.005 grandfathered old global symbol names by providing preprocessor
22 macros for extension source compatibility. As of release 5.006, these
23 preprocessor definitions are not available by default. You need to explicitly
24 compile perl with C<-DPERL_POLLUTE> in order to get these definitions.
26 =item C<PERL_POLLUTE_MALLOC>
28 Enabling the use of Perl's malloc in release 5.005 and earlier caused
29 the namespace of system versions of the malloc family of functions to
30 be usurped by the Perl versions of these functions, since they used the
31 same names by default.
33 Besides causing problems on platforms that do not allow these functions to
34 be cleanly replaced, this also meant that the system versions could not
35 be called in programs that used Perl's malloc. Previous versions of Perl
36 have allowed this behavior to be suppressed with the HIDEMYMALLOC and
37 EMBEDMYMALLOC preprocessor definitions.
39 As of release 5.006, Perl's malloc family of functions have default names
40 distinct from the system versions. You need to explicitly compile perl with
41 C<-DPERL_POLLUTE_MALLOC> in order to get the older behavior. HIDEMYMALLOC
42 and EMBEDMYMALLOC have no effect, since the behavior they enabled is now
45 Note that these functions do B<not> constitute Perl's memory allocation API.
46 See L<perlguts/"Memory Allocation"> for further information about that.
48 =item C<PL_na> and C<dTHR> Issues
50 The C<PL_na> global is now thread local, so a C<dTHR> declaration is needed
51 in the scope in which it appears. XSUBs should handle this automatically,
52 but if you have used C<PL_na> in support functions, you either need to
53 change the C<PL_na> to a local variable (which is recommended), or put in
58 =head2 Compatible C Source API Changes
62 =item C<PATCHLEVEL> is now C<PERL_VERSION>
64 The cpp macros C<PERL_REVISION>, C<PERL_VERSION> and C<PERL_SUBVERSION>
65 are now available by default from perl.h, and reflect the base revision,
66 patchlevel and subversion respectively. C<PERL_REVISION> had no
67 prior equivalent, while C<PERL_VERSION> and C<PERL_SUBVERSION> were
68 previously available as C<PATCHLEVEL> and C<SUBVERSION>.
70 The new names cause less pollution of the cpp namespace, and reflect what
71 the numbers have come to stand for in common practice. For compatibility,
72 the old names are still supported when patchlevel.h is explicitly
73 included (as required before), so there is no source incompatibility
78 =head2 Binary Incompatibilities
80 This release is not binary compatible with the 5.005 release and its
85 =head2 Unicode and UTF-8 support
87 Perl can optionally use UTF-8 as its internal representation for character
88 strings. The C<use utf8> pragma enables this support in the current lexical
89 scope. See L<utf8> for more information.
91 =head2 Lexically scoped warning categories
93 You can now control the granularity of warnings emitted by perl at a finer
94 level using the C<use warning> pragma. See L<warning> for details.
96 =head2 Binary numbers supported
98 Binary numbers are now supported as literals, in s?printf formats, and
102 printf "The answer is: %b\n", oct("0b101010");
104 =head2 syswrite() ease-of-use
106 The length argument of C<syswrite()> is now optional.
108 =head2 64-bit support
110 Better 64-bit support -- but full support still a distant goal. One
111 must Configure with -Duse64bits to get Configure to probe for the
112 extent of 64-bit support. Depending on the platform (hints file) more
113 or less 64-awareness becomes available. As of 5.005_54 at least
114 somewhat 64-bit aware platforms are HP-UX 11 or better, Solaris 2.6 or
115 better, IRIX 6.2 or better. Naturally 64-bit platforms like Digital
116 UNIX and UNICOS also have 64-bit support.
118 =head2 Better syntax checks on parenthesized unary operators
122 print defined(&foo,&bar,&baz);
123 print uc("foo","bar","baz");
126 used to be accidentally allowed in earlier versions, and produced
127 unpredictable behavior. Some of them produced ancillary warnings
128 when used in this way, while others silently did the wrong thing.
130 The parenthesized forms of most unary operators that expect a single
131 argument will now ensure that they are not called with more than one
132 argument, making the above cases syntax errors. Note that the usual
135 print defined &foo, &bar, &baz;
136 print uc "foo", "bar", "baz";
139 remains unchanged. See L<perlop>.
141 =head2 Improved C<qw//> operator
143 The C<qw//> operator is now evaluated at compile time into a true list
144 instead of being replaced with a run time call to C<split()>. This
145 removes the confusing behavior of C<qw//> in scalar context stemming from
146 the older implementation, which inherited the behavior from split().
150 $foo = ($bar) = qw(a b c); print "$foo|$bar\n";
152 now correctly prints "3|a", instead of "2|a".
154 =head2 pack() format 'Z' supported
156 The new format type 'Z' is useful for packing and unpacking null-terminated
157 strings. See L<perlfunc/"pack">.
159 =head2 pack() format modifier '_' supported
161 The new format type modifer '_' is useful for packing and unpacking
162 native shorts, ints, and longs. See L<perlfunc/"pack">.
164 =head1 Significant bug fixes
166 =head2 E<lt>HANDLEE<gt> on empty files
168 With C<$/> set to C<undef>, slurping an empty file returns a string of
169 zero length (instead of C<undef>, as it used to) for the first time the
170 HANDLE is read. Subsequent reads yield C<undef>.
172 This means that the following will append "foo" to an empty file (it used
173 to not do anything before):
175 perl -0777 -pi -e 's/^/foo/' empty_file
177 Note that the behavior of:
179 perl -pi -e 's/^/foo/' empty_file
181 is unchanged (it continues to leave the file empty).
183 =head1 Supported Platforms
189 VM/ESA is now supported.
193 Siemens BS2000 is now supported under the POSIX Shell.
197 The Mach CThreads (NEXTSTEP, OPENSTEP) are now supported by the Thread
202 GNU/Hurd is now supported.
212 IO constants (SEEK_*, _IO*).
216 Directory-related IO methods (new, read, close, rewind, tied delete).
218 =item op/io_multihomed
220 INET sockets with multi-homed hosts.
236 Verify operations that access pad objects (lexicals and temporaries).
240 =head1 Modules and Pragmata
248 Added Dumpvalue module provides screen dumps of Perl data.
252 You can now run tests for I<x> seconds instead of guessing the right
253 number of tests to run.
257 More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for
258 large (more than 4G) file access (the 64-bit support is not yet
259 working, though, so no need to get overly excited), Free/Net/OpenBSD
260 locking behaviour flags F_FLOCK, F_POSIX, Linux F_SHLCK, and
261 O_ACCMODE: the mask of O_RDONLY, O_WRONLY, and O_RDWR.
265 The accessors methods Re, Im, arg, abs, rho, theta, methods can
266 ($z->Re()) now also act as mutators ($z->Re(3)).
270 A little bit of radial trigonometry (cylindrical and spherical) added,
271 for example the great circle distance.
275 The timelocal() and timegm() functions used to silently return bogus
276 results when the date exceeded the machine's integer range. They
277 consistently croak() if the date falls in an unsupported range.
283 C<use utf8;>, to enable UTF-8 and Unicode support.
285 Lexical warnings pragma, C<use warning;>, to control optional warnings.
287 C<use filetest;>, to control the behaviour of filetests (C<-r> C<-w> ...).
288 Currently only one subpragma implemented, "use filetest 'access';",
289 that enables the use of access(2) or equivalent to check the
290 permissions instead of using stat(2) as usual. This matters
291 in filesystems where there are ACLs (access control lists), the
292 stat(2) might lie, while access(2) knows better.
294 =head1 Utility Changes
298 =head1 Documentation Changes
302 =item perlopentut.pod
304 A tutorial on using open() effectively.
308 A tutorial that introduces the essentials of references.
312 =head1 New Diagnostics
314 =item /%s/: Unrecognized escape \\%c passed through
316 (W) You used a backslash-character combination which is not recognized
317 by Perl. This combination appears in an interpolated variable or a
318 C<'>-delimited regular expression.
320 =item Unrecognized escape \\%c passed through
322 (W) You used a backslash-character combination which is not recognized
325 =item Missing command in piped open
327 (W) You used the C<open(FH, "| command")> or C<open(FH, "command |")>
328 construction, but the command was missing or blank.
330 =head1 Obsolete Diagnostics
334 =head1 Configuration Changes
336 You can use "Configure -Uinstallusrbinperl" which causes installperl
337 to skip installing perl also as /usr/bin/perl. This is useful if you
338 prefer not to modify /usr/bin for some reason or another but harmful
339 because many scripts assume to find Perl in /usr/bin/perl.
341 =head1 Configuration Changes
343 You can use "Configure -Uinstallusrbinperl" which causes installperl
344 to skip installing perl also as /usr/bin/perl. This is useful if you
345 prefer not to modify /usr/bin for some reason or another but harmful
346 because many scripts assume to find Perl in /usr/bin/perl.
350 If you find what you think is a bug, you might check the headers of
351 recently posted articles in the comp.lang.perl.misc newsgroup.
352 There may also be information at http://www.perl.com/perl/, the Perl
355 If you believe you have an unreported bug, please run the B<perlbug>
356 program included with your release. Make sure you trim your bug down
357 to a tiny but sufficient test case. Your bug report, along with the
358 output of C<perl -V>, will be sent off to <F<perlbug@perl.com>> to be
359 analysed by the Perl porting team.
363 The F<Changes> file for exhaustive details on what changed.
365 The F<INSTALL> file for how to build Perl.
367 The F<README> file for general stuff.
369 The F<Artistic> and F<Copying> files for copyright information.
373 Written by Gurusamy Sarathy <F<gsar@umich.edu>>, with many contributions
374 from The Perl Porters.
376 Send omissions or corrections to <F<perlbug@perl.com>>.