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01784f0d AD |
1 | =head1 NAME |
2 | ||
3 | perldelta - what's new for perl5.005 | |
4 | ||
5 | =head1 DESCRIPTION | |
6 | ||
7 | This document describes differences between the 5.004 release and this one. | |
8 | ||
429b3afa GS |
9 | =head1 About the new versioning system |
10 | ||
9cde0e7f GS |
11 | Perl is now developed on two tracks: a maintenance track that makes |
12 | small, safe updates to released production versions with emphasis on | |
13 | compatibility; and a development track that pursues more aggressive | |
14 | evolution. Maintenance releases (which should be considered production | |
15 | quality) have subversion numbers that run from C<1> to C<49>, and | |
16 | development releases (which should be considered "alpha" quality) run | |
17 | from C<50> to C<99>. | |
18 | ||
19 | Perl 5.005 is the combined product of the new dual-track development | |
20 | scheme. | |
21 | ||
01784f0d AD |
22 | =head1 Incompatible Changes |
23 | ||
429b3afa GS |
24 | =head2 WARNING: This version is not binary compatible with Perl 5.004. |
25 | ||
26 | Starting with Perl 5.004_50 there were many deep and far-reaching changes | |
27 | to the language internals. If you have dynamically loaded extensions | |
28 | that you built under perl 5.003 or 5.004, you can continue to use them | |
29 | with 5.004, but you will need to rebuild and reinstall those extensions | |
b4bc034f | 30 | to use them 5.005. See F<INSTALL> for detailed instructions on how to |
429b3afa GS |
31 | upgrade. |
32 | ||
7ea97eb9 | 33 | =head2 Default installation structure has changed |
429b3afa | 34 | |
7ea97eb9 | 35 | The new Configure defaults are designed to allow a smooth upgrade from |
b4bc034f | 36 | 5.004 to 5.005, but you should read F<INSTALL> for a detailed |
7ea97eb9 | 37 | discussion of the changes in order to adapt them to your system. |
429b3afa GS |
38 | |
39 | =head2 Perl Source Compatibility | |
40 | ||
41 | When none of the experimental features are enabled, there should be | |
9cde0e7f | 42 | very few user-visible Perl source compatibility issues. |
429b3afa GS |
43 | |
44 | If threads are enabled, then some caveats apply. C<@_> and C<$_> become | |
45 | lexical variables. The effect of this should be largely transparent to | |
46 | the user, but there are some boundary conditions under which user will | |
9cde0e7f GS |
47 | need to be aware of the issues. For example, C<local(@_)> results in |
48 | a "Can't localize lexical variable @_ ..." message. This may be enabled | |
49 | in a future version. | |
429b3afa | 50 | |
fe61ab85 | 51 | Some new keywords have been introduced. These are generally expected to |
9cde0e7f GS |
52 | have very little impact on compatibility. See L<New C<INIT> keyword>, |
53 | L<New C<lock> keyword>, and L<New C<qr//> operator>. | |
fe61ab85 GS |
54 | |
55 | Certain barewords are now reserved. Use of these will provoke a warning | |
56 | if you have asked for them with the C<-w> switch. | |
9cde0e7f | 57 | See L<C<our> is now a reserved word>. |
fe61ab85 | 58 | |
429b3afa GS |
59 | =head2 C Source Compatibility |
60 | ||
9cde0e7f GS |
61 | There have been a large number of changes in the internals to support |
62 | the new features in this release. | |
63 | ||
64 | =over 4 | |
65 | ||
429b3afa GS |
66 | =item Core sources now require ANSI C compiler |
67 | ||
9cde0e7f GS |
68 | An ANSI C compiler is now B<required> to build perl. See F<INSTALL>. |
69 | ||
70 | =item All Perl global variables must now be referenced with an explicit prefix | |
71 | ||
72 | All Perl global variables that are visible for use by extensions now | |
73 | have a C<PL_> prefix. New extensions should C<not> refer to perl globals | |
74 | by their unqualified names. To preserve sanity, we provide limited | |
75 | backward compatibility for globals that are being widely used like | |
76 | C<sv_undef> and C<na> (which should now be written as C<PL_sv_undef>, | |
77 | C<PL_na> etc.) | |
78 | ||
79 | If you find that your XS extension does not compile anymore because a | |
80 | perl global is not visible, try adding a C<PL_> prefix to the global | |
81 | and rebuild. | |
82 | ||
83 | It is strongly recommended that all functions in the Perl API that don't | |
84 | begin with C<perl> be referenced with a C<Perl_> prefix. The bare function | |
85 | names without the C<Perl_> prefix are supported with macros, but this | |
86 | support may cease in a future release. | |
87 | ||
b687b08b | 88 | See L<perlguts/"API LISTING">. |
9cde0e7f | 89 | |
429b3afa GS |
90 | =item Enabling threads has source compatibility issues |
91 | ||
9cde0e7f GS |
92 | Perl built with threading enabled requires extensions to use the new |
93 | C<dTHR> macro to initialize the handle to access per-thread data. | |
94 | If you see a compiler error that talks about the variable C<thr> not | |
95 | being declared (when building a module that has XS code), you need | |
96 | to add C<dTHR;> at the beginning of the block that elicited the error. | |
97 | ||
98 | The API function C<perl_get_sv("@",FALSE)> should be used instead of | |
99 | directly accessing perl globals as C<GvSV(errgv)>. The API call is | |
100 | backward compatible with existing perls and provides source compatibility | |
101 | with threading is enabled. | |
102 | ||
b687b08b | 103 | See L<"C Source Compatibility"> for more information. |
9cde0e7f GS |
104 | |
105 | =back | |
106 | ||
429b3afa GS |
107 | =head2 Binary Compatibility |
108 | ||
109 | This version is NOT binary compatible with older versions. All extensions | |
9cde0e7f GS |
110 | will need to be recompiled. Further binaries built with threads enabled |
111 | are incompatible with binaries built without. This should largely be | |
112 | transparent to the user, as all binary incompatible configurations have | |
113 | their own unique architecture name, and extension binaries get installed at | |
114 | unique locations. This allows coexistence of several configurations in | |
115 | the same directory hierarchy. See F<INSTALL>. | |
429b3afa GS |
116 | |
117 | =head2 Security fixes may affect compatibility | |
118 | ||
119 | A few taint leaks and taint omissions have been corrected. This may lead | |
120 | to "failure" of scripts that used to work with older versions. Compiling | |
121 | with -DINCOMPLETE_TAINTS provides a perl with minimal amounts of changes | |
122 | to the tainting behavior. But note that the resulting perl will have | |
123 | known insecurities. | |
124 | ||
125 | Oneliners with the C<-e> switch do not create temporary files anymore. | |
126 | ||
127 | =head2 Relaxed new mandatory warnings introduced in 5.004 | |
128 | ||
fe61ab85 | 129 | Many new warnings that were introduced in 5.004 have been made |
429b3afa GS |
130 | optional. Some of these warnings are still present, but perl's new |
131 | features make them less often a problem. See L<New Diagnostics>. | |
132 | ||
133 | =head2 Licensing | |
134 | ||
fe61ab85 | 135 | Perl has a new Social Contract for contributors. See F<Porting/Contract>. |
429b3afa | 136 | |
fe61ab85 | 137 | The license included in much of the Perl documentation has changed. |
b8957cf1 GS |
138 | Most of the Perl documentation was previously under the implicit GNU |
139 | General Public License or the Artistic License (at the user's choice). | |
c2611fb3 | 140 | Now much of the documentation unambiguously states the terms under which |
b8957cf1 GS |
141 | it may be distributed. Those terms are in general much less restrictive |
142 | than the GNU GPL. See L<perl> and the individual perl man pages listed | |
143 | therein. | |
429b3afa | 144 | |
01784f0d AD |
145 | =head1 Core Changes |
146 | ||
01784f0d | 147 | |
429b3afa GS |
148 | =head2 Threads |
149 | ||
9cde0e7f | 150 | WARNING: Threading is considered an B<experimental> feature. Details of the |
429b3afa | 151 | implementation may change without notice. There are known limitations |
9cde0e7f | 152 | and some bugs. These are expected to be fixed in future versions. |
429b3afa | 153 | |
b4bc034f | 154 | See F<README.threads>. |
429b3afa GS |
155 | |
156 | =head2 Compiler | |
157 | ||
9cde0e7f | 158 | WARNING: The Compiler and related tools are considered B<experimental>. |
429b3afa | 159 | Features may change without notice, and there are known limitations |
9cde0e7f GS |
160 | and bugs. Since the compiler is fully external to perl, the default |
161 | configuration will build and install it. | |
429b3afa | 162 | |
fe61ab85 GS |
163 | The Compiler produces three different types of transformations of a |
164 | perl program. The C backend generates C code that captures perl's state | |
165 | just before execution begins. It eliminates the compile-time overheads | |
166 | of the regular perl interpreter, but the run-time performance remains | |
167 | comparatively the same. The CC backend generates optimized C code | |
88c0f958 | 168 | equivalent to the code path at run-time. The CC backend has greater |
fe61ab85 GS |
169 | potential for big optimizations, but only a few optimizations are |
170 | implemented currently. The Bytecode backend generates a platform | |
171 | independent bytecode representation of the interpreter's state | |
172 | just before execution. Thus, the Bytecode back end also eliminates | |
173 | much of the compilation overhead of the interpreter. | |
174 | ||
175 | The compiler comes with several valuable utilities. | |
176 | ||
177 | C<B::Lint> is an experimental module to detect and warn about suspicious | |
178 | code, especially the cases that the C<-w> switch does not detect. | |
179 | ||
180 | C<B::Deparse> can be used to demystify perl code, and understand | |
181 | how perl optimizes certain constructs. | |
182 | ||
183 | C<B::Xref> generates cross reference reports of all definition and use | |
184 | of variables, subroutines and formats in a program. | |
429b3afa | 185 | |
fe61ab85 GS |
186 | C<B::Showlex> show the lexical variables used by a subroutine or file |
187 | at a glance. | |
188 | ||
189 | C<perlcc> is a simple frontend for compiling perl. | |
429b3afa | 190 | |
9cde0e7f | 191 | See C<ext/B/README>, L<B>, and the respective compiler modules. |
429b3afa GS |
192 | |
193 | =head2 Regular Expressions | |
194 | ||
9cde0e7f GS |
195 | Perl's regular expression engine has been seriously overhauled, and |
196 | many new constructs are supported. Several bugs have been fixed. | |
197 | ||
198 | Here is an itemized summary: | |
199 | ||
200 | =over 4 | |
201 | ||
202 | =item Many new and improved optimizations | |
203 | ||
204 | Changes in the RE engine: | |
205 | ||
206 | Unneeded nodes removed; | |
207 | Substrings merged together; | |
208 | New types of nodes to process (SUBEXPR)* and similar expressions | |
209 | quickly, used if the SUBEXPR has no side effects and matches | |
210 | strings of the same length; | |
88c0f958 | 211 | Better optimizations by lookup for constant substrings; |
9cde0e7f GS |
212 | Better search for constants substrings anchored by $ ; |
213 | ||
214 | Changes in Perl code using RE engine: | |
215 | ||
88c0f958 | 216 | More optimizations to s/longer/short/; |
9cde0e7f GS |
217 | study() was not working; |
218 | /blah/ may be optimized to an analogue of index() if $& $` $' not seen; | |
219 | Unneeded copying of matched-against string removed; | |
220 | Only matched part of the string is copying if $` $' were not seen; | |
221 | ||
222 | =item Many bug fixes | |
223 | ||
224 | Note that only the major bug fixes are listed here. See F<Changes> for others. | |
225 | ||
226 | Backtracking might not restore start of $3. | |
227 | No feedback if max count for * or + on "complex" subexpression | |
228 | was reached, similarly (but at compile time) for {3,34567} | |
229 | Primitive restrictions on max count introduced to decrease a | |
230 | possibility of a segfault; | |
231 | (ZERO-LENGTH)* could segfault; | |
232 | (ZERO-LENGTH)* was prohibited; | |
88c0f958 | 233 | Long REs were not allowed; |
9cde0e7f GS |
234 | /RE/g could skip matches at the same position after a |
235 | zero-length match; | |
236 | ||
237 | =item New regular expression constructs | |
238 | ||
239 | The following new syntax elements are supported: | |
240 | ||
241 | (?<=RE) | |
242 | (?<!RE) | |
243 | (?{ CODE }) | |
244 | (?i-x) | |
245 | (?i:RE) | |
246 | (?(COND)YES_RE|NO_RE) | |
247 | (?>RE) | |
248 | \z | |
249 | ||
250 | =item New operator for precompiled regular expressions | |
251 | ||
252 | See L<New C<qr//> operator>. | |
253 | ||
254 | =item Other improvements | |
255 | ||
88c0f958 HB |
256 | Better debugging output (possibly with colors), |
257 | even from non-debugging Perl; | |
9cde0e7f | 258 | RE engine code now looks like C, not like assembler; |
88c0f958 | 259 | Behaviour of RE modifiable by `use re' directive; |
9cde0e7f GS |
260 | Improved documentation; |
261 | Test suite significantly extended; | |
262 | Syntax [:^upper:] etc., reserved inside character classes; | |
263 | ||
264 | =item Incompatible changes | |
265 | ||
266 | (?i) localized inside enclosing group; | |
267 | $( is not interpolated into RE any more; | |
268 | /RE/g may match at the same position (with non-zero length) | |
269 | after a zero-length match (bug fix). | |
270 | ||
271 | =back | |
272 | ||
429b3afa GS |
273 | See L<perlre> and L<perlop>. |
274 | ||
275 | =head2 Improved malloc() | |
276 | ||
277 | See banner at the beginning of C<malloc.c> for details. | |
278 | ||
279 | =head2 Quicksort is internally implemented | |
280 | ||
9cde0e7f GS |
281 | Perl now contains its own highly optimized qsort() routine. The new qsort() |
282 | is resistant to inconsistent comparison functions, so Perl's C<sort()> will | |
283 | not provoke coredumps any more when given poorly written sort subroutines. | |
284 | (Some C library C<qsort()>s that were being used before used to have this | |
285 | problem.) In our testing, the new C<qsort()> required the minimal number | |
286 | of pair-wise compares on average, among all known C<qsort()> implementations. | |
287 | ||
429b3afa GS |
288 | See C<perlfunc/sort>. |
289 | ||
290 | =head2 Reliable signals | |
291 | ||
9cde0e7f GS |
292 | Perl's signal handling is susceptible to random crashes, because signals |
293 | arrive asynchronously, and the Perl runtime is not reentrant at arbitrary | |
294 | times. | |
fe61ab85 | 295 | |
9cde0e7f GS |
296 | However, one experimental implementation of reliable signals is available |
297 | when threads are enabled. See C<Thread::Signal>. Also see F<INSTALL> for | |
298 | how to build a Perl capable of threads. | |
429b3afa GS |
299 | |
300 | =head2 Reliable stack pointers | |
301 | ||
fe61ab85 | 302 | The internals now reallocate the perl stack only at predictable times. |
429b3afa GS |
303 | In particular, magic calls never trigger reallocations of the stack, |
304 | because all reentrancy of the runtime is handled using a "stack of stacks". | |
fe61ab85 GS |
305 | This should improve reliability of cached stack pointers in the internals |
306 | and in XSUBs. | |
429b3afa | 307 | |
637e9122 GS |
308 | =head2 More generous treatment of carriage returns |
309 | ||
b8957cf1 GS |
310 | Perl used to complain if it encountered literal carriage returns in |
311 | scripts. Now they are mostly treated like whitespace within program text. | |
312 | Inside string literals and here documents, literal carriage returns are | |
453f83e7 | 313 | ignored if they occur paired with linefeeds, or get interpreted as whitespace |
b8957cf1 GS |
314 | if they stand alone. This behavior means that literal carriage returns |
315 | in files should be avoided. You can get the older, more compatible (but | |
316 | less generous) behavior by defining the preprocessor symbol | |
317 | C<PERL_STRICT_CR> when building perl. Of course, all this has nothing | |
318 | whatever to do with how escapes like C<\r> are handled within strings. | |
637e9122 GS |
319 | |
320 | Note that this doesn't somehow magically allow you to keep all text files | |
321 | in DOS format. The generous treatment only applies to files that perl | |
322 | itself parses. If your C compiler doesn't allow carriage returns in | |
323 | files, you may still be unable to build modules that need a C compiler. | |
324 | ||
325 | =head2 Memory leaks | |
326 | ||
327 | C<substr>, C<pos> and C<vec> don't leak memory anymore when used in lvalue | |
328 | context. Many small leaks that impacted applications that embed multiple | |
329 | interpreters have been fixed. | |
330 | ||
331 | =head2 Better support for multiple interpreters | |
332 | ||
333 | The build-time option C<-DMULTIPLICITY> has had many of the details | |
334 | reworked. Some previously global variables that should have been | |
335 | per-interpreter now are. With care, this allows interpreters to call | |
336 | each other. See the C<PerlInterp> extension on CPAN. | |
337 | ||
407eff0f | 338 | =head2 Behavior of local() on array and hash elements is now well-defined |
429b3afa | 339 | |
407eff0f | 340 | See L<perlsub/"Temporary Values via local()">. |
429b3afa GS |
341 | |
342 | =head2 C<%!> is transparently tied to the L<Errno> module | |
343 | ||
fe61ab85 | 344 | See L<perlvar>, and L<Errno>. |
429b3afa GS |
345 | |
346 | =head2 Pseudo-hashes are supported | |
347 | ||
348 | See L<perlref>. | |
349 | ||
350 | =head2 C<EXPR foreach EXPR> is supported | |
351 | ||
352 | See L<perlsyn>. | |
353 | ||
429b3afa GS |
354 | =head2 Keywords can be globally overridden |
355 | ||
356 | See L<perlsub>. | |
357 | ||
358 | =head2 C<$^E> is meaningful on Win32 | |
359 | ||
360 | See L<perlvar>. | |
361 | ||
362 | =head2 C<foreach (1..1000000)> optimized | |
363 | ||
364 | C<foreach (1..1000000)> is now optimized into a counting loop. It does | |
365 | not try to allocate a 1000000-size list anymore. | |
366 | ||
367 | =head2 C<Foo::> can be used as implicitly quoted package name | |
368 | ||
9cde0e7f GS |
369 | Barewords caused unintuitive behavior when a subroutine with the same |
370 | name as a package happened to be defined. Thus, C<new Foo @args>, | |
371 | use the result of the call to C<Foo()> instead of C<Foo> being treated | |
372 | as a literal. The recommended way to write barewords in the indirect | |
373 | object slot is C<new Foo:: @args>. Note that the method C<new()> is | |
374 | called with a first argument of C<Foo>, not C<Foo::> when you do that. | |
429b3afa GS |
375 | |
376 | =head2 C<exists $Foo::{Bar::}> tests existence of a package | |
377 | ||
9cde0e7f GS |
378 | It was impossible to test for the existence of a package without |
379 | actually creating it before. Now C<exists $Foo::{Bar::}> can be | |
380 | used to test if the C<Foo::Bar> namespace has been created. | |
429b3afa GS |
381 | |
382 | =head2 Better locale support | |
383 | ||
384 | See L<perllocale>. | |
385 | ||
7ea97eb9 | 386 | =head2 Experimental support for 64-bit platforms |
429b3afa | 387 | |
7ea97eb9 AD |
388 | Perl5 has always had 64-bit support on systems with 64-bit longs. |
389 | Starting with 5.005, the beginnings of experimental support for systems | |
390 | with 32-bit long and 64-bit 'long long' integers has been added. | |
391 | If you add -DUSE_LONG_LONG to your ccflags in config.sh (or manually | |
392 | define it in perl.h) then perl will be built with 'long long' support. | |
393 | There will be many compiler warnings, and the resultant perl may not | |
394 | work on all systems. There are many other issues related to | |
395 | third-party extensions and libraries. This option exists to allow | |
396 | people to work on those issues. | |
429b3afa GS |
397 | |
398 | =head2 prototype() returns useful results on builtins | |
399 | ||
400 | See L<perlfunc/prototype>. | |
401 | ||
1a159553 GS |
402 | =head2 Extended support for exception handling |
403 | ||
404 | C<die()> now accepts a reference value, and C<$@> gets set to that | |
405 | value in exception traps. This makes it possible to propagate | |
9cde0e7f | 406 | exception objects. This is an undocumented B<experimental> feature. |
1a159553 | 407 | |
429b3afa GS |
408 | =head2 Re-blessing in DESTROY() supported for chaining DESTROY() methods |
409 | ||
410 | See L<perlobj/Destructors>. | |
411 | ||
412 | =head2 All C<printf> format conversions are handled internally | |
413 | ||
414 | See L<perlfunc/printf>. | |
415 | ||
416 | =head2 New C<INIT> keyword | |
417 | ||
fe61ab85 GS |
418 | C<INIT> subs are like C<BEGIN> and C<END>, but they get run just before |
419 | the perl runtime begins execution. e.g., the Perl Compiler makes use of | |
420 | C<INIT> blocks to initialize and resolve pointers to XSUBs. | |
429b3afa | 421 | |
429b3afa GS |
422 | =head2 New C<lock> keyword |
423 | ||
fe61ab85 GS |
424 | The C<lock> keyword is the fundamental synchronization primitive |
425 | in threaded perl. When threads are not enabled, it is currently a noop. | |
426 | ||
429b3afa GS |
427 | To minimize impact on source compatibility this keyword is "weak", i.e., any |
428 | user-defined subroutine of the same name overrides it, unless a C<use Thread> | |
429 | has been seen. | |
430 | ||
fe61ab85 GS |
431 | =head2 New C<qr//> operator |
432 | ||
433 | The C<qr//> operator, which is syntactically similar to the other quote-like | |
0a92e3a8 | 434 | operators, is used to create precompiled regular expressions. This compiled |
fe61ab85 | 435 | form can now be explicitly passed around in variables, and interpolated in |
0a92e3a8 | 436 | other regular expressions. See L<perlop>. |
fe61ab85 GS |
437 | |
438 | =head2 C<our> is now a reserved word | |
439 | ||
9cde0e7f GS |
440 | Calling a subroutine with the name C<our> will now provoke a warning when |
441 | using the C<-w> switch. | |
442 | ||
429b3afa GS |
443 | =head2 Tied arrays are now fully supported |
444 | ||
445 | See L<Tie::Array>. | |
446 | ||
447 | =head2 Tied handles support is better | |
448 | ||
449 | Several missing hooks have been added. There is also a new base class for | |
450 | TIEARRAY implementations. See L<Tie::Array>. | |
451 | ||
6bb4e6d4 GS |
452 | =head2 4th argument to substr |
453 | ||
454 | substr() can now both return and replace in one operation. The optional | |
455 | 4th argument is the replacement string. See L<perlfunc/substr>. | |
456 | ||
457 | =head2 Negative LENGTH argument to splice | |
458 | ||
88c0f958 | 459 | splice() with a negative LENGTH argument now work similar to what the |
6bb4e6d4 GS |
460 | LENGTH did for substr(). Previously a negative LENGTH was treated as |
461 | 0. See L<perlfunc/splice>. | |
462 | ||
407eff0f SM |
463 | =head2 Magic lvalues are now more magical |
464 | ||
465 | When you say something like C<substr($x, 5) = "hi">, the scalar returned | |
466 | by substr() is special, in that any modifications to it affect $x. | |
467 | (This is called a 'magic lvalue' because an 'lvalue' is something on | |
468 | the left side of an assignment.) Normally, this is exactly what you | |
469 | would expect to happen, but Perl uses the same magic if you use substr(), | |
470 | pos(), or vec() in a context where they might be modified, like taking | |
471 | a reference with C<\> or as an argument to a sub that modifies C<@_>. | |
472 | In previous versions, this 'magic' only went one way, but now changes | |
473 | to the scalar the magic refers to ($x in the above example) affect the | |
474 | magic lvalue too. For instance, this code now acts differently: | |
475 | ||
476 | $x = "hello"; | |
477 | sub printit { | |
478 | $x = "g'bye"; | |
479 | print $_[0], "\n"; | |
480 | } | |
481 | printit(substr($x, 0, 5)); | |
482 | ||
483 | In previous versions, this would print "hello", but it now prints "g'bye". | |
484 | ||
3bf5f72b GS |
485 | =head2 E<lt>E<gt> now reads in records |
486 | ||
c2611fb3 | 487 | If C<$/> is a reference to an integer, or a scalar that holds an integer, |
3bf5f72b GS |
488 | E<lt>E<gt> will read in records instead of lines. For more info, see |
489 | L<perlvar/$/>. | |
429b3afa GS |
490 | |
491 | =head1 Supported Platforms | |
492 | ||
493 | Configure has many incremental improvements. Site-wide policy for building | |
fe61ab85 | 494 | perl can now be made persistent, via Policy.sh. Configure also records |
7ea97eb9 | 495 | the command-line arguments used in F<config.sh>. |
429b3afa GS |
496 | |
497 | =head2 New Platforms | |
498 | ||
b4bc034f | 499 | BeOS is now supported. See F<README.beos>. |
429b3afa | 500 | |
b4bc034f GS |
501 | DOS is now supported under the DJGPP tools. See F<README.dos> (installed |
502 | as L<perldos> on some systems). | |
429b3afa | 503 | |
b4bc034f | 504 | MiNT is now supported. See F<README.mint>. |
f3d48bde | 505 | |
b4bc034f | 506 | MPE/iX is now supported. See F<README.mpeix>. |
1d84e8df | 507 | |
b4bc034f GS |
508 | MVS (aka OS390, aka Open Edition) is now supported. See F<README.os390> |
509 | (installed as L<perlos390> on some systems). | |
6c67e1bb | 510 | |
b4bc034f | 511 | Stratus VOS is now supported. See F<README.vos>. |
9d116dd7 | 512 | |
429b3afa GS |
513 | =head2 Changes in existing support |
514 | ||
515 | Win32 support has been vastly enhanced. Support for Perl Object, a C++ | |
516 | encapsulation of Perl. GCC and EGCS are now supported on Win32. | |
9cde0e7f | 517 | See F<README.win32>, aka L<perlwin32>. |
429b3afa | 518 | |
b4bc034f GS |
519 | VMS configuration system has been rewritten. See F<README.vms> (installed |
520 | as L<README_vms> on some systems). | |
429b3afa | 521 | |
9cde0e7f | 522 | The hints files for most Unix platforms have seen incremental improvements. |
429b3afa GS |
523 | |
524 | =head1 Modules and Pragmata | |
525 | ||
526 | =head2 New Modules | |
527 | ||
528 | =over | |
529 | ||
530 | =item B | |
531 | ||
9cde0e7f | 532 | Perl compiler and tools. See L<B>. |
429b3afa GS |
533 | |
534 | =item Data::Dumper | |
535 | ||
536 | A module to pretty print Perl data. See L<Data::Dumper>. | |
537 | ||
f3d48bde GS |
538 | =item Dumpvalue |
539 | ||
540 | A module to dump perl values to the screen. See L<Dumpvalue>. | |
541 | ||
429b3afa GS |
542 | =item Errno |
543 | ||
544 | A module to look up errors more conveniently. See L<Errno>. | |
545 | ||
546 | =item File::Spec | |
547 | ||
548 | A portable API for file operations. | |
549 | ||
550 | =item ExtUtils::Installed | |
551 | ||
552 | Query and manage installed modules. | |
553 | ||
554 | =item ExtUtils::Packlist | |
555 | ||
556 | Manipulate .packlist files. | |
557 | ||
558 | =item Fatal | |
559 | ||
560 | Make functions/builtins succeed or die. | |
561 | ||
562 | =item IPC::SysV | |
563 | ||
564 | Constants and other support infrastructure for System V IPC operations | |
565 | in perl. | |
566 | ||
567 | =item Test | |
568 | ||
569 | A framework for writing testsuites. | |
01784f0d | 570 | |
429b3afa GS |
571 | =item Tie::Array |
572 | ||
573 | Base class for tied arrays. | |
574 | ||
575 | =item Tie::Handle | |
576 | ||
577 | Base class for tied handles. | |
578 | ||
579 | =item Thread | |
580 | ||
581 | Perl thread creation, manipulation, and support. | |
582 | ||
583 | =item attrs | |
584 | ||
585 | Set subroutine attributes. | |
586 | ||
587 | =item fields | |
588 | ||
589 | Compile-time class fields. | |
590 | ||
591 | =item re | |
592 | ||
593 | Various pragmata to control behavior of regular expressions. | |
594 | ||
595 | =back | |
596 | ||
597 | =head2 Changes in existing modules | |
598 | ||
599 | =over | |
600 | ||
2eac2f99 TC |
601 | =item Benchmark |
602 | ||
603 | You can now run tests for I<x> seconds instead of guessing the right | |
604 | number of tests to run. | |
605 | ||
f3d48bde GS |
606 | =item Carp |
607 | ||
608 | Carp has a new function cluck(). cluck() warns, like carp(), but also adds | |
609 | a stack backtrace to the error message, like confess(). | |
610 | ||
429b3afa GS |
611 | =item CGI |
612 | ||
613 | CGI has been updated to version 2.42. | |
614 | ||
2eac2f99 TC |
615 | =item Fcntl |
616 | ||
617 | More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for | |
618 | large (more than 4G) file access (the 64-bit support is not yet | |
619 | working, though, so no need to get overly excited), Free/Net/OpenBSD | |
620 | locking behaviour flags F_FLOCK, F_POSIX, Linux F_SHLCK, and | |
621 | O_ACCMODE: the mask of O_RDONLY, O_WRONLY, and O_RDWR. | |
622 | ||
623 | =item Math::Complex | |
f3d48bde GS |
624 | |
625 | The accessors methods Re, Im, arg, abs, rho, theta, methods can | |
626 | ($z->Re()) now also act as mutators ($z->Re(3)). | |
627 | ||
628 | =item Math::Trig | |
629 | ||
2eac2f99 TC |
630 | A little bit of radial trigonometry (cylindrical and spherical) added, |
631 | for example the great circle distance. | |
632 | ||
429b3afa GS |
633 | =item POSIX |
634 | ||
635 | POSIX now has its own platform-specific hints files. | |
636 | ||
637 | =item DB_File | |
638 | ||
639 | DB_File supports version 2.x of Berkeley DB. See C<ext/DB_File/Changes>. | |
640 | ||
641 | =item MakeMaker | |
642 | ||
643 | MakeMaker now supports writing empty makefiles, provides a way to | |
644 | specify that site umask() policy should be honored. There is also | |
645 | better support for manipulation of .packlist files, and getting | |
646 | information about installed modules. | |
647 | ||
7ea97eb9 AD |
648 | Extensions that have both architecture-dependent and |
649 | architecture-independent files are now always installed completely in | |
650 | the architecture-dependent locations. Previously, the shareable parts | |
651 | were shared both across architectures and across perl versions and were | |
652 | therefore liable to be overwritten with newer versions that might have | |
653 | subtle incompatibilities. | |
654 | ||
429b3afa GS |
655 | =item CPAN |
656 | ||
9cde0e7f | 657 | See <perlmodinstall> and L<CPAN>. |
429b3afa GS |
658 | |
659 | =item Cwd | |
660 | ||
661 | Cwd::cwd is faster on most platforms. | |
662 | ||
663 | =item Benchmark | |
664 | ||
665 | Keeps better time. | |
666 | ||
667 | =back | |
01784f0d AD |
668 | |
669 | =head1 Utility Changes | |
670 | ||
637e9122 GS |
671 | C<h2ph> and related utilities have been vastly overhauled. |
672 | ||
673 | C<perlcc>, a new experimental front end for the compiler is available. | |
429b3afa | 674 | |
637e9122 GS |
675 | The crude GNU C<configure> emulator is now called C<configure.gnu> to |
676 | avoid trampling on C<Configure> under case-insensitive filesystems. | |
429b3afa | 677 | |
637e9122 GS |
678 | C<perldoc> used to be rather slow. The slower features are now optional. |
679 | In particular, case-insensitive searches need the C<-i> switch, and | |
680 | recursive searches need C<-r>. You can set these switches in the | |
681 | C<PERLDOC> environment variable to get the old behavior. | |
7ea97eb9 | 682 | |
01784f0d AD |
683 | =head1 Documentation Changes |
684 | ||
429b3afa GS |
685 | Config.pm now has a glossary of variables. |
686 | ||
9cde0e7f | 687 | F<Porting/patching.pod> has detailed instructions on how to create and |
429b3afa GS |
688 | submit patches for perl. |
689 | ||
9cde0e7f GS |
690 | L<perlport> specifies guidelines on how to write portably. |
691 | ||
692 | L<perlmodinstall> describes how to fetch and install modules from C<CPAN> | |
693 | sites. | |
694 | ||
695 | Some more Perl traps are documented now. See L<perltrap>. | |
696 | ||
f3d48bde GS |
697 | L<perlopentut> gives a tutorial on using open(). |
698 | ||
699 | L<perlreftut> gives a tutorial on references. | |
700 | ||
701 | L<perlthrtut> gives a tutorial on threads. | |
702 | ||
429b3afa GS |
703 | =head1 New Diagnostics |
704 | ||
705 | =over | |
706 | ||
707 | =item Ambiguous call resolved as CORE::%s(), qualify as such or use & | |
708 | ||
709 | (W) A subroutine you have declared has the same name as a Perl keyword, | |
710 | and you have used the name without qualification for calling one or the | |
711 | other. Perl decided to call the builtin because the subroutine is | |
712 | not imported. | |
713 | ||
714 | To force interpretation as a subroutine call, either put an ampersand | |
715 | before the subroutine name, or qualify the name with its package. | |
716 | Alternatively, you can import the subroutine (or pretend that it's | |
717 | imported with the C<use subs> pragma). | |
718 | ||
719 | To silently interpret it as the Perl operator, use the C<CORE::> prefix | |
720 | on the operator (e.g. C<CORE::log($x)>) or by declaring the subroutine | |
721 | to be an object method (see L<attrs>). | |
722 | ||
723 | =item Bad index while coercing array into hash | |
724 | ||
725 | (F) The index looked up in the hash found as the 0'th element of a | |
726 | pseudo-hash is not legal. Index values must be at 1 or greater. | |
727 | See L<perlref>. | |
728 | ||
729 | =item Bareword "%s" refers to nonexistent package | |
730 | ||
731 | (W) You used a qualified bareword of the form C<Foo::>, but | |
732 | the compiler saw no other uses of that namespace before that point. | |
733 | Perhaps you need to predeclare a package? | |
734 | ||
735 | =item Can't call method "%s" on an undefined value | |
736 | ||
737 | (F) You used the syntax of a method call, but the slot filled by the | |
738 | object reference or package name contains an undefined value. | |
739 | Something like this will reproduce the error: | |
740 | ||
741 | $BADREF = 42; | |
742 | process $BADREF 1,2,3; | |
743 | $BADREF->process(1,2,3); | |
744 | ||
f3d48bde GS |
745 | =item Can't check filesystem of script "%s" for nosuid |
746 | ||
747 | (P) For some reason you can't check the filesystem of the script for nosuid. | |
748 | ||
429b3afa GS |
749 | =item Can't coerce array into hash |
750 | ||
751 | (F) You used an array where a hash was expected, but the array has no | |
752 | information on how to map from keys to array indices. You can do that | |
753 | only with arrays that have a hash reference at index 0. | |
754 | ||
755 | =item Can't goto subroutine from an eval-string | |
756 | ||
757 | (F) The "goto subroutine" call can't be used to jump out of an eval "string". | |
758 | (You can use it to jump out of an eval {BLOCK}, but you probably don't want to.) | |
759 | ||
0ebe0038 SM |
760 | =item Can't localize pseudo-hash element |
761 | ||
762 | (F) You said something like C<local $ar-E<gt>{'key'}>, where $ar is | |
763 | a reference to a pseudo-hash. That hasn't been implemented yet, but | |
764 | you can get a similar effect by localizing the corresponding array | |
765 | element directly -- C<local $ar-E<gt>[$ar-E<gt>[0]{'key'}]>. | |
766 | ||
429b3afa GS |
767 | =item Can't use %%! because Errno.pm is not available |
768 | ||
769 | (F) The first time the %! hash is used, perl automatically loads the | |
770 | Errno.pm module. The Errno module is expected to tie the %! hash to | |
771 | provide symbolic names for C<$!> errno values. | |
772 | ||
429b3afa GS |
773 | =item Cannot find an opnumber for "%s" |
774 | ||
775 | (F) A string of a form C<CORE::word> was given to prototype(), but | |
776 | there is no builtin with the name C<word>. | |
777 | ||
778 | =item Character class syntax [. .] is reserved for future extensions | |
779 | ||
780 | (W) Within regular expression character classes ([]) the syntax beginning | |
781 | with "[." and ending with ".]" is reserved for future extensions. | |
782 | If you need to represent those character sequences inside a regular | |
783 | expression character class, just quote the square brackets with the | |
784 | backslash: "\[." and ".\]". | |
785 | ||
786 | =item Character class syntax [: :] is reserved for future extensions | |
787 | ||
788 | (W) Within regular expression character classes ([]) the syntax beginning | |
789 | with "[:" and ending with ":]" is reserved for future extensions. | |
790 | If you need to represent those character sequences inside a regular | |
791 | expression character class, just quote the square brackets with the | |
792 | backslash: "\[:" and ":\]". | |
793 | ||
794 | =item Character class syntax [= =] is reserved for future extensions | |
795 | ||
796 | (W) Within regular expression character classes ([]) the syntax | |
797 | beginning with "[=" and ending with "=]" is reserved for future extensions. | |
798 | If you need to represent those character sequences inside a regular | |
799 | expression character class, just quote the square brackets with the | |
800 | backslash: "\[=" and "=\]". | |
801 | ||
802 | =item %s: Eval-group in insecure regular expression | |
803 | ||
804 | (F) Perl detected tainted data when trying to compile a regular expression | |
805 | that contains the C<(?{ ... })> zero-width assertion, which is unsafe. | |
806 | See L<perlre/(?{ code })>, and L<perlsec>. | |
807 | ||
808 | =item %s: Eval-group not allowed, use re 'eval' | |
809 | ||
810 | (F) A regular expression contained the C<(?{ ... })> zero-width assertion, | |
811 | but that construct is only allowed when the C<use re 'eval'> pragma is | |
812 | in effect. See L<perlre/(?{ code })>. | |
813 | ||
814 | =item %s: Eval-group not allowed at run time | |
815 | ||
816 | (F) Perl tried to compile a regular expression containing the C<(?{ ... })> | |
817 | zero-width assertion at run time, as it would when the pattern contains | |
818 | interpolated values. Since that is a security risk, it is not allowed. | |
819 | If you insist, you may still do this by explicitly building the pattern | |
820 | from an interpolated string at run time and using that in an eval(). | |
821 | See L<perlre/(?{ code })>. | |
822 | ||
823 | =item Explicit blessing to '' (assuming package main) | |
824 | ||
825 | (W) You are blessing a reference to a zero length string. This has | |
826 | the effect of blessing the reference into the package main. This is | |
827 | usually not what you want. Consider providing a default target | |
ae6c4aac | 828 | package, e.g. bless($ref, $p || 'MyPackage'); |
429b3afa GS |
829 | |
830 | =item Illegal hex digit ignored | |
831 | ||
832 | (W) You may have tried to use a character other than 0 - 9 or A - F in a | |
833 | hexadecimal number. Interpretation of the hexadecimal number stopped | |
834 | before the illegal character. | |
835 | ||
836 | =item No such array field | |
837 | ||
838 | (F) You tried to access an array as a hash, but the field name used is | |
839 | not defined. The hash at index 0 should map all valid field names to | |
840 | array indices for that to work. | |
841 | ||
842 | =item No such field "%s" in variable %s of type %s | |
843 | ||
844 | (F) You tried to access a field of a typed variable where the type | |
845 | does not know about the field name. The field names are looked up in | |
846 | the %FIELDS hash in the type package at compile time. The %FIELDS hash | |
847 | is usually set up with the 'fields' pragma. | |
848 | ||
849 | =item Out of memory during ridiculously large request | |
850 | ||
851 | (F) You can't allocate more than 2^31+"small amount" bytes. This error | |
852 | is most likely to be caused by a typo in the Perl program. e.g., C<$arr[time]> | |
853 | instead of C<$arr[$time]>. | |
854 | ||
855 | =item Range iterator outside integer range | |
856 | ||
857 | (F) One (or both) of the numeric arguments to the range operator ".." | |
858 | are outside the range which can be represented by integers internally. | |
859 | One possible workaround is to force Perl to use magical string | |
860 | increment by prepending "0" to your numbers. | |
861 | ||
862 | =item Recursive inheritance detected while looking for method '%s' in package '%s' | |
863 | ||
864 | (F) More than 100 levels of inheritance were encountered while invoking a | |
865 | method. Probably indicates an unintended loop in your inheritance hierarchy. | |
866 | ||
867 | =item Reference found where even-sized list expected | |
868 | ||
869 | (W) You gave a single reference where Perl was expecting a list with | |
870 | an even number of elements (for assignment to a hash). This | |
871 | usually means that you used the anon hash constructor when you meant | |
872 | to use parens. In any case, a hash requires key/value B<pairs>. | |
873 | ||
874 | %hash = { one => 1, two => 2, }; # WRONG | |
875 | %hash = [ qw/ an anon array / ]; # WRONG | |
876 | %hash = ( one => 1, two => 2, ); # right | |
877 | %hash = qw( one 1 two 2 ); # also fine | |
878 | ||
879 | =item Undefined value assigned to typeglob | |
880 | ||
881 | (W) An undefined value was assigned to a typeglob, a la C<*foo = undef>. | |
882 | This does nothing. It's possible that you really mean C<undef *foo>. | |
883 | ||
884 | =item Use of reserved word "%s" is deprecated | |
885 | ||
886 | (D) The indicated bareword is a reserved word. Future versions of perl | |
887 | may use it as a keyword, so you're better off either explicitly quoting | |
888 | the word in a manner appropriate for its context of use, or using a | |
889 | different name altogether. The warning can be suppressed for subroutine | |
890 | names by either adding a C<&> prefix, or using a package qualifier, | |
891 | e.g. C<&our()>, or C<Foo::our()>. | |
892 | ||
893 | =item perl: warning: Setting locale failed. | |
894 | ||
895 | (S) The whole warning message will look something like: | |
896 | ||
897 | perl: warning: Setting locale failed. | |
898 | perl: warning: Please check that your locale settings: | |
899 | LC_ALL = "En_US", | |
900 | LANG = (unset) | |
901 | are supported and installed on your system. | |
902 | perl: warning: Falling back to the standard locale ("C"). | |
903 | ||
904 | Exactly what were the failed locale settings varies. In the above the | |
905 | settings were that the LC_ALL was "En_US" and the LANG had no value. | |
906 | This error means that Perl detected that you and/or your system | |
907 | administrator have set up the so-called variable system but Perl could | |
908 | not use those settings. This was not dead serious, fortunately: there | |
909 | is a "default locale" called "C" that Perl can and will use, the | |
910 | script will be run. Before you really fix the problem, however, you | |
911 | will get the same error message each time you run Perl. How to really | |
2eac2f99 | 912 | fix the problem can be found in L<perllocale/"LOCALE PROBLEMS">. |
429b3afa GS |
913 | |
914 | =back | |
915 | ||
916 | ||
917 | =head1 Obsolete Diagnostics | |
918 | ||
919 | =over | |
6cc33c6d | 920 | |
429b3afa GS |
921 | =item Can't mktemp() |
922 | ||
923 | (F) The mktemp() routine failed for some reason while trying to process | |
924 | a B<-e> switch. Maybe your /tmp partition is full, or clobbered. | |
925 | ||
2eac2f99 TC |
926 | Removed because B<-e> doesn't use temporary files any more. |
927 | ||
429b3afa GS |
928 | =item Can't write to temp file for B<-e>: %s |
929 | ||
930 | (F) The write routine failed for some reason while trying to process | |
931 | a B<-e> switch. Maybe your /tmp partition is full, or clobbered. | |
932 | ||
2eac2f99 TC |
933 | Removed because B<-e> doesn't use temporary files any more. |
934 | ||
429b3afa GS |
935 | =item Cannot open temporary file |
936 | ||
937 | (F) The create routine failed for some reason while trying to process | |
938 | a B<-e> switch. Maybe your /tmp partition is full, or clobbered. | |
939 | ||
2eac2f99 TC |
940 | Removed because B<-e> doesn't use temporary files any more. |
941 | ||
0f31cffe GS |
942 | =item regexp too big |
943 | ||
944 | (F) The current implementation of regular expressions uses shorts as | |
945 | address offsets within a string. Unfortunately this means that if | |
946 | the regular expression compiles to longer than 32767, it'll blow up. | |
947 | Usually when you want a regular expression this big, there is a better | |
be59e445 GS |
948 | way to do it with multiple statements. See L<perlre>. |
949 | ||
f3d48bde | 950 | =back |
0f31cffe | 951 | |
f3d48bde | 952 | =head1 Configuration Changes |
0f31cffe | 953 | |
f3d48bde GS |
954 | You can use "Configure -Uinstallusrbinperl" which causes installperl |
955 | to skip installing perl also as /usr/bin/perl. This is useful if you | |
956 | prefer not to modify /usr/bin for some reason or another but harmful | |
957 | because many scripts assume to find Perl in /usr/bin/perl. | |
429b3afa | 958 | |
01784f0d AD |
959 | =head1 BUGS |
960 | ||
961 | If you find what you think is a bug, you might check the headers of | |
962 | recently posted articles in the comp.lang.perl.misc newsgroup. | |
963 | There may also be information at http://www.perl.com/perl/, the Perl | |
964 | Home Page. | |
965 | ||
966 | If you believe you have an unreported bug, please run the B<perlbug> | |
967 | program included with your release. Make sure you trim your bug down | |
968 | to a tiny but sufficient test case. Your bug report, along with the | |
969 | output of C<perl -V>, will be sent off to <F<perlbug@perl.com>> to be | |
970 | analysed by the Perl porting team. | |
971 | ||
972 | =head1 SEE ALSO | |
973 | ||
974 | The F<Changes> file for exhaustive details on what changed. | |
975 | ||
976 | The F<INSTALL> file for how to build Perl. | |
977 | ||
978 | The F<README> file for general stuff. | |
979 | ||
980 | The F<Artistic> and F<Copying> files for copyright information. | |
981 | ||
982 | =head1 HISTORY | |
429b3afa | 983 | |
6e238990 | 984 | Written by Gurusamy Sarathy <F<gsar@activestate.com>>, with many contributions |
9cde0e7f GS |
985 | from The Perl Porters. |
986 | ||
987 | Send omissions or corrections to <F<perlbug@perl.com>>. | |
988 | ||
429b3afa | 989 | =cut |