3 perldelta - what's new for perl5.006 (as of 5.005_54)
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 =head1 Significant bug fixes
161 =head2 E<lt>HANDLEE<gt> on empty files
163 With C<$/> set to C<undef>, slurping an empty file returns a string of
164 zero length (instead of C<undef>, as it used to) for the first time the
165 HANDLE is read. Subsequent reads yield C<undef>.
167 This means that the following will append "foo" to an empty file (it used
168 to not do anything before):
170 perl -0777 -pi -e 's/^/foo/' empty_file
172 Note that the behavior of:
174 perl -pi -e 's/^/foo/' empty_file
176 is unchanged (it continues to leave the file empty).
178 =head2 pack() format modifier '_' supported
180 The new format type modifer '_' is useful for packing and unpacking
181 native shorts, ints, and longs. See L<perlfunc/"pack">.
183 =head1 Supported Platforms
189 VM/ESA is now supported.
193 Siemens BS200 is now supported.
197 The Mach CThreads (NeXTstep) are now supported by the Thread extension.
207 IO constants (SEEK_*, _IO*).
211 Directory-related IO methods (new, read, close, rewind, tied delete).
213 =item op/io_multihomed
215 INET sockets with multi-homed hosts.
231 Verify operations that access pad objects (lexicals and temporaries).
235 =head1 Modules and Pragmata
243 Added Dumpvalue module provides screen dumps of Perl data.
247 You can now run tests for I<x> seconds instead of guessing the right
248 number of tests to run.
252 More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for
253 large (more than 4G) file access (the 64-bit support is not yet
254 working, though, so no need to get overly excited), Free/Net/OpenBSD
255 locking behaviour flags F_FLOCK, F_POSIX, Linux F_SHLCK, and
256 O_ACCMODE: the mask of O_RDONLY, O_WRONLY, and O_RDWR.
260 The accessors methods Re, Im, arg, abs, rho, theta, methods can
261 ($z->Re()) now also act as mutators ($z->Re(3)).
265 A little bit of radial trigonometry (cylindrical and spherical) added,
266 for example the great circle distance.
270 The timelocal() and timegm() functions used to silently return bogus
271 results when the date exceeded the machine's integer range. They
272 consistently croak() if the date falls in an unsupported range.
278 C<use utf8;>, to enable UTF-8 and Unicode support.
280 Lexical warnings pragma, C<use warning;>, to control optional warnings.
282 C<use filetest;>, to control the behaviour of filetests (C<-r> C<-w> ...).
283 Currently only one subpragma implemented, "use filetest 'access';",
284 that enables the use of access(2) or equivalent to check the
285 permissions instead of using stat(2) as usual. This matters
286 in filesystems where there are ACLs (access control lists), the
287 stat(2) might lie, while access(2) knows better.
289 =head1 Utility Changes
293 =head1 Documentation Changes
297 =item perlopentut.pod
299 A tutorial on using open() effectively.
303 A tutorial that introduces the essentials of references.
307 =head1 New Diagnostics
309 =item /%s/: Unrecognized escape \\%c passed through
311 (W) You used a backslash-character combination which is not recognized
312 by Perl. This combination appears in an interpolated variable or a
313 C<'>-delimited regular expression.
315 =item Unrecognized escape \\%c passed through
317 (W) You used a backslash-character combination which is not recognized
320 =item Missing command in piped open
322 (W) You used the C<open(FH, "| command")> or C<open(FH, "command |")>
323 construction, but the command was missing or blank.
325 =head1 Obsolete Diagnostics
329 =head1 Configuration Changes
331 You can use "Configure -Uinstallusrbinperl" which causes installperl
332 to skip installing perl also as /usr/bin/perl. This is useful if you
333 prefer not to modify /usr/bin for some reason or another but harmful
334 because many scripts assume to find Perl in /usr/bin/perl.
338 If you find what you think is a bug, you might check the headers of
339 recently posted articles in the comp.lang.perl.misc newsgroup.
340 There may also be information at http://www.perl.com/perl/, the Perl
343 If you believe you have an unreported bug, please run the B<perlbug>
344 program included with your release. Make sure you trim your bug down
345 to a tiny but sufficient test case. Your bug report, along with the
346 output of C<perl -V>, will be sent off to <F<perlbug@perl.com>> to be
347 analysed by the Perl porting team.
351 The F<Changes> file for exhaustive details on what changed.
353 The F<INSTALL> file for how to build Perl.
355 The F<README> file for general stuff.
357 The F<Artistic> and F<Copying> files for copyright information.
361 Written by Gurusamy Sarathy <F<gsar@umich.edu>>, with many contributions
362 from The Perl Porters.
364 Send omissions or corrections to <F<perlbug@perl.com>>.