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 Binary numbers supported
87 Binary numbers are now supported as literals, in s?printf formats, and
91 printf "The answer is: %b\n", oct("0b101010");
93 =head2 syswrite() ease-of-use
95 The length argument of C<syswrite()> is now optional.
99 Better 64-bit support -- but full support still a distant goal. One
100 must Configure with -Duse64bits to get Configure to probe for the
101 extent of 64-bit support. Depending on the platform (hints file) more
102 or less 64-awareness becomes available. As of 5.005_54 at least
103 somewhat 64-bit aware platforms are HP-UX 11 or better, Solaris 2.6 or
104 better, IRIX 6.2 or better. Naturally 64-bit platforms like Digital
105 UNIX and UNICOS also have 64-bit support.
107 =head2 Better syntax checks on parenthesized unary operators
111 print defined(&foo,&bar,&baz);
112 print uc("foo","bar","baz");
115 used to be accidentally allowed in earlier versions, and produced
116 unpredictable behavior. Some of them produced ancillary warnings
117 when used in this way, while others silently did the wrong thing.
119 The parenthesized forms of most unary operators that expect a single
120 argument will now ensure that they are not called with more than one
121 argument, making the above cases syntax errors. Note that the usual
124 print defined &foo, &bar, &baz;
125 print uc "foo", "bar", "baz";
128 remains unchanged. See L<perlop>.
130 =head2 Improved C<qw//> operator
132 The C<qw//> operator is now evaluated at compile time into a true list
133 instead of being replaced with a run time call to C<split()>. This
134 removes the confusing behavior of C<qw//> in scalar context stemming from
135 the older implementation, which inherited the behavior from split().
139 $foo = ($bar) = qw(a b c); print "$foo|$bar\n";
141 now correctly prints "3|a", instead of "2|a".
143 =head2 pack() format 'Z' supported
145 The new format type 'Z' is useful for packing and unpacking null-terminated
146 strings. See L<perlfunc/"pack">.
148 =head1 Significant bug fixes
150 =head2 E<lt>HANDLEE<gt> on empty files
152 With C<$/> set to C<undef>, slurping an empty file returns a string of
153 zero length (instead of C<undef>, as it used to) for the first time the
154 HANDLE is read. Subsequent reads yield C<undef>.
156 This means that the following will append "foo" to an empty file (it used
157 to not do anything before):
159 perl -0777 -pi -e 's/^/foo/' empty_file
161 Note that the behavior of:
163 perl -pi -e 's/^/foo/' empty_file
165 is unchanged (it continues to leave the file empty).
167 =head2 pack() format modifier '_' supported
169 The new format type modifer '_' is useful for packing and unpacking
170 native shorts, ints, and longs. See L<perlfunc/"pack">.
172 =head1 Supported Platforms
178 VM/ESA is now supported.
182 Siemens BS200 is now supported.
186 The Mach CThreads (NeXTstep) are now supported by the Thread extension.
196 IO constants (SEEK_*, _IO*).
200 Directory-related IO methods (new, read, close, rewind, tied delete).
202 =item op/io_multihomed
204 INET sockets with multi-homed hosts.
220 Verify operations that access pad objects (lexicals and temporaries).
224 =head1 Modules and Pragmata
232 Added Dumpvalue module provides screen dumps of Perl data.
236 You can now run tests for I<x> seconds instead of guessing the right
237 number of tests to run.
241 More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for
242 large (more than 4G) file access (the 64-bit support is not yet
243 working, though, so no need to get overly excited), Free/Net/OpenBSD
244 locking behaviour flags F_FLOCK, F_POSIX, Linux F_SHLCK, and
245 O_ACCMODE: the mask of O_RDONLY, O_WRONLY, and O_RDWR.
249 The accessors methods Re, Im, arg, abs, rho, theta, methods can
250 ($z->Re()) now also act as mutators ($z->Re(3)).
254 A little bit of radial trigonometry (cylindrical and spherical) added,
255 for example the great circle distance.
259 The timelocal() and timegm() functions used to silently return bogus
260 results when the date exceeded the machine's integer range. They
261 consistently croak() if the date falls in an unsupported range.
267 Lexical warnings pragma, "use warning;", to control optional warnings.
269 Filetest pragma, to control the behaviour of filetests (C<-r> C<-w> ...).
270 Currently only one subpragma implemented, "use filetest 'access';",
271 that enables the use of access(2) or equivalent to check the
272 permissions instead of using stat(2) as usual. This matters
273 in filesystems where there are ACLs (access control lists), the
274 stat(2) might lie, while access(2) knows better.
276 =head1 Utility Changes
280 =head1 Documentation Changes
284 =item perlopentut.pod
286 A tutorial on using open() effectively.
290 A tutorial that introduces the essentials of references.
294 =head1 New Diagnostics
296 =item /%s/: Unrecognized escape \\%c passed through
298 (W) You used a backslash-character combination which is not recognized
299 by Perl. This combination appears in an interpolated variable or a
300 C<'>-delimited regular expression.
302 =item Unrecognized escape \\%c passed through
304 (W) You used a backslash-character combination which is not recognized
307 =item Missing command in piped open
309 (W) You used the C<open(FH, "| command")> or C<open(FH, "command |")>
310 construction, but the command was missing or blank.
312 =head1 Obsolete Diagnostics
316 =head1 Configuration Changes
318 You can use "Configure -Uinstallusrbinperl" which causes installperl
319 to skip installing perl also as /usr/bin/perl. This is useful if you
320 prefer not to modify /usr/bin for some reason or another but harmful
321 because many scripts assume to find Perl in /usr/bin/perl.
325 If you find what you think is a bug, you might check the headers of
326 recently posted articles in the comp.lang.perl.misc newsgroup.
327 There may also be information at http://www.perl.com/perl/, the Perl
330 If you believe you have an unreported bug, please run the B<perlbug>
331 program included with your release. Make sure you trim your bug down
332 to a tiny but sufficient test case. Your bug report, along with the
333 output of C<perl -V>, will be sent off to <F<perlbug@perl.com>> to be
334 analysed by the Perl porting team.
338 The F<Changes> file for exhaustive details on what changed.
340 The F<INSTALL> file for how to build Perl.
342 The F<README> file for general stuff.
344 The F<Artistic> and F<Copying> files for copyright information.
348 Written by Gurusamy Sarathy <F<gsar@umich.edu>>, with many contributions
349 from The Perl Porters.
351 Send omissions or corrections to <F<perlbug@perl.com>>.