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1 | =head1 NAME |
2 | |
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3 | perldelta - what's new for perl5.006 (as of 5.005_56) |
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4 | |
5 | =head1 DESCRIPTION |
6 | |
7 | This document describes differences between the 5.005 release and this one. |
8 | |
9 | =head1 Incompatible Changes |
10 | |
e02fdbd2 |
11 | =head2 Perl Source Incompatibilities |
12 | |
13 | None known at this time. |
14 | |
15 | =head2 C Source Incompatibilities |
16 | |
17 | =over 4 |
18 | |
19 | =item C<PERL_POLLUTE> |
20 | |
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. |
25 | |
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26 | =item C<PERL_POLLUTE_MALLOC> |
27 | |
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. |
32 | |
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. |
38 | |
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 |
43 | the default. |
44 | |
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. |
47 | |
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48 | =item C<PL_na> and C<dTHR> Issues |
49 | |
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 |
54 | a C<dTHR>. |
55 | |
56 | =back |
57 | |
cceca5ed |
58 | =head2 Compatible C Source API Changes |
59 | |
60 | =over |
61 | |
62 | =item C<PATCHLEVEL> is now C<PERL_VERSION> |
63 | |
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>. |
69 | |
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 |
74 | due to the change. |
75 | |
76 | =back |
77 | |
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78 | =head2 Binary Incompatibilities |
79 | |
80 | This release is not binary compatible with the 5.005 release and its |
81 | maintenance versions. |
82 | |
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83 | =head1 Core Changes |
84 | |
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85 | =head2 Unicode and UTF-8 support |
86 | |
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. |
90 | |
91 | =head2 Lexically scoped warning categories |
92 | |
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. |
95 | |
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96 | =head2 Binary numbers supported |
97 | |
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98 | Binary numbers are now supported as literals, in s?printf formats, and |
99 | C<oct()>: |
100 | |
101 | $answer = 0b101010; |
102 | printf "The answer is: %b\n", oct("0b101010"); |
103 | |
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104 | =head2 syswrite() ease-of-use |
105 | |
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106 | The length argument of C<syswrite()> is now optional. |
107 | |
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108 | =head2 64-bit support |
109 | |
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110 | Better 64-bit support -- but full support still a distant goal. One |
111 | must Configure with -Duse64bits to get Configure to probe for the |
112 | extent of 64-bit support. Depending on the platform (hints file) more |
113 | or less 64-awareness becomes available. As of 5.005_54 at least |
114 | somewhat 64-bit aware platforms are HP-UX 11 or better, Solaris 2.6 or |
115 | better, IRIX 6.2 or better. Naturally 64-bit platforms like Digital |
116 | UNIX and UNICOS also have 64-bit support. |
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117 | |
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118 | =head2 Better syntax checks on parenthesized unary operators |
119 | |
120 | Expressions such as: |
121 | |
122 | print defined(&foo,&bar,&baz); |
123 | print uc("foo","bar","baz"); |
124 | undef($foo,&bar); |
125 | |
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. |
129 | |
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 |
133 | behavior of: |
134 | |
135 | print defined &foo, &bar, &baz; |
136 | print uc "foo", "bar", "baz"; |
137 | undef $foo, &bar; |
138 | |
139 | remains unchanged. See L<perlop>. |
140 | |
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141 | =head2 Improved C<qw//> operator |
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142 | |
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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(). |
147 | |
148 | Thus: |
149 | |
150 | $foo = ($bar) = qw(a b c); print "$foo|$bar\n"; |
151 | |
152 | now correctly prints "3|a", instead of "2|a". |
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153 | |
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154 | =head2 pack() format 'Z' supported |
155 | |
156 | The new format type 'Z' is useful for packing and unpacking null-terminated |
157 | strings. See L<perlfunc/"pack">. |
158 | |
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159 | =head2 pack() format modifier '!' supported |
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160 | |
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161 | The new format type modifer '!' is useful for packing and unpacking |
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162 | native shorts, ints, and longs. See L<perlfunc/"pack">. |
163 | |
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164 | =head2 $^X variables may now have names longer than one character |
165 | |
166 | Formerly, $^X was synonymous with ${"\cX"}, but $^XY was a syntax |
167 | error. Now variable names that begin with a control character may be |
168 | arbitrarily long. However, for compatibility reasons, these variables |
169 | I<must> be written with explicit braces, as C<${^XY}> for example. |
170 | C<${^XYZ}> is synonymous with ${"\cXYZ"}. Variable names with more |
171 | than one control character, such as C<${^XY^Z}>, are illegal. |
172 | |
173 | The old syntax has not changed. As before, the `^X' may either be a |
174 | literal control-X character or the two character sequence `caret' plus |
175 | `X'. When the braces are omitted, the variable name stops after the |
176 | control character. Thus C<"$^XYZ"> continues to be synonymous with |
177 | C<$^X . "YZ"> as before. |
178 | |
179 | As before, lexical variables may not have names beginning with control |
180 | characters. As before, variables whose names begin with a control |
181 | character are always forced to be in package `main'. These variables |
182 | are all reserved for future extensions, except the ones that begin |
183 | with C<^_>, which may be used by user programs and will not acquire a |
184 | special meaning in any future version of Perl. |
185 | |
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186 | =head1 Significant bug fixes |
187 | |
188 | =head2 E<lt>HANDLEE<gt> on empty files |
189 | |
190 | With C<$/> set to C<undef>, slurping an empty file returns a string of |
191 | zero length (instead of C<undef>, as it used to) for the first time the |
192 | HANDLE is read. Subsequent reads yield C<undef>. |
193 | |
194 | This means that the following will append "foo" to an empty file (it used |
195 | to not do anything before): |
196 | |
197 | perl -0777 -pi -e 's/^/foo/' empty_file |
198 | |
199 | Note that the behavior of: |
200 | |
201 | perl -pi -e 's/^/foo/' empty_file |
202 | |
203 | is unchanged (it continues to leave the file empty). |
204 | |
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205 | =head2 C<eval '...'> improvements |
206 | |
207 | Line numbers (as reflected by caller() and most diagnostics) within |
208 | C<eval '...'> were often incorrect when here documents were involved. |
209 | This has been corrected. |
210 | |
211 | Lexical lookups for variables appearing in C<eval '...'> within |
212 | functions that were themselves called within an C<eval '...'> were |
213 | searching the wrong place for lexicals. They now correctly terminate |
214 | the lexical search at the subroutine call boundary. |
215 | |
216 | Parsing of here documents used to be flawed when they appeared as |
217 | the replacement expression in C<eval 's/.../.../e'>. This has |
218 | been fixed. |
219 | |
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220 | =head1 Supported Platforms |
221 | |
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222 | =over 4 |
223 | |
224 | =item * |
225 | |
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226 | VM/ESA is now supported. |
227 | |
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228 | =item * |
229 | |
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230 | Siemens BS2000 is now supported under the POSIX Shell. |
231 | |
232 | =item * |
233 | |
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234 | The Mach CThreads (NEXTSTEP, OPENSTEP) are now supported by the Thread |
235 | extension. |
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236 | |
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237 | =item * |
238 | |
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239 | GNU/Hurd is now supported. |
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240 | |
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241 | =back |
242 | |
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243 | =head1 New tests |
244 | |
245 | =over 4 |
246 | |
247 | =item op/io_const |
248 | |
249 | IO constants (SEEK_*, _IO*). |
250 | |
251 | =item op/io_dir |
252 | |
253 | Directory-related IO methods (new, read, close, rewind, tied delete). |
254 | |
255 | =item op/io_multihomed |
256 | |
257 | INET sockets with multi-homed hosts. |
258 | |
259 | =item op/io_poll |
260 | |
261 | IO poll(). |
262 | |
263 | =item op/io_unix |
264 | |
265 | UNIX sockets. |
266 | |
267 | =item op/filetest |
268 | |
269 | File test operators. |
270 | |
271 | =item op/lex_assign |
272 | |
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273 | Verify operations that access pad objects (lexicals and temporaries). |
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274 | |
275 | =back |
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276 | |
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277 | =head1 Modules and Pragmata |
278 | |
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279 | =head2 Modules |
280 | |
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281 | =over 4 |
282 | |
283 | =item Dumpvalue |
284 | |
285 | Added Dumpvalue module provides screen dumps of Perl data. |
286 | |
287 | =item Benchmark |
288 | |
289 | You can now run tests for I<x> seconds instead of guessing the right |
290 | number of tests to run. |
291 | |
292 | =item Fcntl |
293 | |
294 | More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for |
295 | large (more than 4G) file access (the 64-bit support is not yet |
296 | working, though, so no need to get overly excited), Free/Net/OpenBSD |
297 | locking behaviour flags F_FLOCK, F_POSIX, Linux F_SHLCK, and |
298 | O_ACCMODE: the mask of O_RDONLY, O_WRONLY, and O_RDWR. |
299 | |
300 | =item Math::Complex |
301 | |
302 | The accessors methods Re, Im, arg, abs, rho, theta, methods can |
303 | ($z->Re()) now also act as mutators ($z->Re(3)). |
304 | |
305 | =item Math::Trig |
306 | |
307 | A little bit of radial trigonometry (cylindrical and spherical) added, |
308 | for example the great circle distance. |
309 | |
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310 | =item Time::Local |
311 | |
312 | The timelocal() and timegm() functions used to silently return bogus |
313 | results when the date exceeded the machine's integer range. They |
314 | consistently croak() if the date falls in an unsupported range. |
315 | |
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316 | =back |
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317 | |
318 | =head2 Pragmata |
319 | |
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320 | C<use utf8;>, to enable UTF-8 and Unicode support. |
321 | |
322 | Lexical warnings pragma, C<use warning;>, to control optional warnings. |
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323 | |
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324 | C<use filetest;>, to control the behaviour of filetests (C<-r> C<-w> ...). |
6c67e1bb |
325 | Currently only one subpragma implemented, "use filetest 'access';", |
326 | that enables the use of access(2) or equivalent to check the |
327 | permissions instead of using stat(2) as usual. This matters |
328 | in filesystems where there are ACLs (access control lists), the |
329 | stat(2) might lie, while access(2) knows better. |
330 | |
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331 | =head1 Utility Changes |
332 | |
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333 | Todo. |
334 | |
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335 | =head1 Documentation Changes |
336 | |
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337 | =over 4 |
338 | |
339 | =item perlopentut.pod |
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340 | |
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341 | A tutorial on using open() effectively. |
342 | |
343 | =item perlreftut.pod |
344 | |
345 | A tutorial that introduces the essentials of references. |
346 | |
347 | =back |
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348 | |
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349 | =head1 New Diagnostics |
350 | |
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351 | =item /%s/: Unrecognized escape \\%c passed through |
352 | |
353 | (W) You used a backslash-character combination which is not recognized |
354 | by Perl. This combination appears in an interpolated variable or a |
355 | C<'>-delimited regular expression. |
356 | |
357 | =item Unrecognized escape \\%c passed through |
358 | |
359 | (W) You used a backslash-character combination which is not recognized |
360 | by Perl. |
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361 | |
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362 | =item Missing command in piped open |
363 | |
364 | (W) You used the C<open(FH, "| command")> or C<open(FH, "command |")> |
365 | construction, but the command was missing or blank. |
366 | |
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367 | =head1 Obsolete Diagnostics |
368 | |
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369 | Todo. |
370 | |
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371 | =head1 Configuration Changes |
372 | |
373 | You can use "Configure -Uinstallusrbinperl" which causes installperl |
374 | to skip installing perl also as /usr/bin/perl. This is useful if you |
375 | prefer not to modify /usr/bin for some reason or another but harmful |
376 | because many scripts assume to find Perl in /usr/bin/perl. |
377 | |
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378 | =head1 BUGS |
379 | |
380 | If you find what you think is a bug, you might check the headers of |
381 | recently posted articles in the comp.lang.perl.misc newsgroup. |
382 | There may also be information at http://www.perl.com/perl/, the Perl |
383 | Home Page. |
384 | |
385 | If you believe you have an unreported bug, please run the B<perlbug> |
386 | program included with your release. Make sure you trim your bug down |
387 | to a tiny but sufficient test case. Your bug report, along with the |
388 | output of C<perl -V>, will be sent off to <F<perlbug@perl.com>> to be |
389 | analysed by the Perl porting team. |
390 | |
391 | =head1 SEE ALSO |
392 | |
393 | The F<Changes> file for exhaustive details on what changed. |
394 | |
395 | The F<INSTALL> file for how to build Perl. |
396 | |
397 | The F<README> file for general stuff. |
398 | |
399 | The F<Artistic> and F<Copying> files for copyright information. |
400 | |
401 | =head1 HISTORY |
402 | |
403 | Written by Gurusamy Sarathy <F<gsar@umich.edu>>, with many contributions |
404 | from The Perl Porters. |
405 | |
406 | Send omissions or corrections to <F<perlbug@perl.com>>. |
407 | |
408 | =cut |