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