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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 | |
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9 | =head1 About the new versioning system |
10 | |
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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 | |
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22 | =head1 Incompatible Changes |
23 | |
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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 |
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30 | to use them 5.005. See F<INSTALL> for detailed instructions on how to |
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31 | upgrade. |
32 | |
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33 | =head2 Default installation structure has changed |
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34 | |
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35 | The new Configure defaults are designed to allow a smooth upgrade from |
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36 | 5.004 to 5.005, but you should read F<INSTALL> for a detailed |
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37 | discussion of the changes in order to adapt them to your system. |
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38 | |
39 | =head2 Perl Source Compatibility |
40 | |
41 | When none of the experimental features are enabled, there should be |
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42 | very few user-visible Perl source compatibility issues. |
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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 |
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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. |
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50 | |
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51 | Some new keywords have been introduced. These are generally expected to |
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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>. |
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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. |
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57 | See L<C<our> is now a reserved word>. |
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58 | |
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59 | =head2 C Source Compatibility |
60 | |
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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 | |
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66 | =item Core sources now require ANSI C compiler |
67 | |
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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 | |
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88 | See L<perlguts/"API LISTING">. |
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89 | |
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90 | =item Enabling threads has source compatibility issues |
91 | |
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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 | |
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103 | See L<"C Source Compatibility"> for more information. |
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104 | |
105 | =back |
106 | |
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107 | =head2 Binary Compatibility |
108 | |
109 | This version is NOT binary compatible with older versions. All extensions |
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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>. |
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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 | |
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129 | Many new warnings that were introduced in 5.004 have been made |
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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 | |
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135 | Perl has a new Social Contract for contributors. See F<Porting/Contract>. |
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136 | |
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137 | The license included in much of the Perl documentation has changed. |
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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). |
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140 | Now much of the documentation unambiguously states the terms under which |
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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. |
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144 | |
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145 | =head1 Core Changes |
146 | |
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147 | |
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148 | =head2 Threads |
149 | |
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150 | WARNING: Threading is considered an B<experimental> feature. Details of the |
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151 | implementation may change without notice. There are known limitations |
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152 | and some bugs. These are expected to be fixed in future versions. |
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153 | |
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154 | See F<README.threads>. |
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155 | |
156 | =head2 Compiler |
157 | |
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158 | WARNING: The Compiler and related tools are considered B<experimental>. |
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159 | Features may change without notice, and there are known limitations |
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160 | and bugs. Since the compiler is fully external to perl, the default |
161 | configuration will build and install it. |
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162 | |
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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 |
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168 | equivalent to the code path at run-time. The CC backend has greater |
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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. |
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185 | |
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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. |
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190 | |
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191 | See C<ext/B/README>, L<B>, and the respective compiler modules. |
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192 | |
193 | =head2 Regular Expressions |
194 | |
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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; |
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211 | Better optimizations by lookup for constant substrings; |
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212 | Better search for constants substrings anchored by $ ; |
213 | |
214 | Changes in Perl code using RE engine: |
215 | |
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216 | More optimizations to s/longer/short/; |
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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; |
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233 | Long REs were not allowed; |
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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 | |
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256 | Better debugging output (possibly with colors), |
257 | even from non-debugging Perl; |
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258 | RE engine code now looks like C, not like assembler; |
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259 | Behaviour of RE modifiable by `use re' directive; |
9cde0e7f |
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 | |
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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 | |
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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 | |
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288 | See C<perlfunc/sort>. |
289 | |
290 | =head2 Reliable signals |
291 | |
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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. |
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295 | |
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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. |
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299 | |
300 | =head2 Reliable stack pointers |
301 | |
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302 | The internals now reallocate the perl stack only at predictable times. |
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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". |
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305 | This should improve reliability of cached stack pointers in the internals |
306 | and in XSUBs. |
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307 | |
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308 | =head2 More generous treatment of carriage returns |
309 | |
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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 |
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313 | ignored if they occur paired with linefeeds, or get interpreted as whitespace |
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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. |
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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 | |
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338 | =head2 Behavior of local() on array and hash elements is now well-defined |
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339 | |
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340 | See L<perlsub/"Temporary Values via local()">. |
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341 | |
342 | =head2 C<%!> is transparently tied to the L<Errno> module |
343 | |
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344 | See L<perlvar>, and L<Errno>. |
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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 | |
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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 | |
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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. |
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375 | |
376 | =head2 C<exists $Foo::{Bar::}> tests existence of a package |
377 | |
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378 | It was impossible to test for the existence of a package without |
379 | actually creating it before. Now C<exists $Foo::{Bar::}> can be |
380 | used to test if the C<Foo::Bar> namespace has been created. |
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381 | |
382 | =head2 Better locale support |
383 | |
384 | See L<perllocale>. |
385 | |
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386 | =head2 Experimental support for 64-bit platforms |
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387 | |
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388 | Perl5 has always had 64-bit support on systems with 64-bit longs. |
389 | Starting with 5.005, the beginnings of experimental support for systems |
390 | with 32-bit long and 64-bit 'long long' integers has been added. |
391 | If you add -DUSE_LONG_LONG to your ccflags in config.sh (or manually |
392 | define it in perl.h) then perl will be built with 'long long' support. |
393 | There will be many compiler warnings, and the resultant perl may not |
394 | work on all systems. There are many other issues related to |
395 | third-party extensions and libraries. This option exists to allow |
396 | people to work on those issues. |
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397 | |
398 | =head2 prototype() returns useful results on builtins |
399 | |
400 | See L<perlfunc/prototype>. |
401 | |
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402 | =head2 Extended support for exception handling |
403 | |
404 | C<die()> now accepts a reference value, and C<$@> gets set to that |
405 | value in exception traps. This makes it possible to propagate |
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406 | exception objects. This is an undocumented B<experimental> feature. |
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407 | |
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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 | |
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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. |
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421 | |
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422 | =head2 New C<lock> keyword |
423 | |
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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 | |
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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 | |
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431 | =head2 New C<qr//> operator |
432 | |
433 | The C<qr//> operator, which is syntactically similar to the other quote-like |
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434 | operators, is used to create precompiled regular expressions. This compiled |
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435 | form can now be explicitly passed around in variables, and interpolated in |
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436 | other regular expressions. See L<perlop>. |
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437 | |
438 | =head2 C<our> is now a reserved word |
439 | |
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440 | Calling a subroutine with the name C<our> will now provoke a warning when |
441 | using the C<-w> switch. |
442 | |
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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 | |
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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 | |
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459 | splice() with a negative LENGTH argument now work similar to what the |
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460 | LENGTH did for substr(). Previously a negative LENGTH was treated as |
461 | 0. See L<perlfunc/splice>. |
462 | |
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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 | |
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485 | =head2 <> now reads in records |
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486 | |
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487 | If C<$/> is a reference to an integer, or a scalar that holds an integer, |
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488 | <> will read in records instead of lines. For more info, see |
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489 | L<perlvar/$/>. |
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490 | |
491 | =head1 Supported Platforms |
492 | |
493 | Configure has many incremental improvements. Site-wide policy for building |
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494 | perl can now be made persistent, via Policy.sh. Configure also records |
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495 | the command-line arguments used in F<config.sh>. |
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496 | |
497 | =head2 New Platforms |
498 | |
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499 | BeOS is now supported. See F<README.beos>. |
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500 | |
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501 | DOS is now supported under the DJGPP tools. See F<README.dos> (installed |
502 | as L<perldos> on some systems). |
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503 | |
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504 | MiNT is now supported. See F<README.mint>. |
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505 | |
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506 | MPE/iX is now supported. See F<README.mpeix>. |
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507 | |
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508 | MVS (aka OS390, aka Open Edition) is now supported. See F<README.os390> |
509 | (installed as L<perlos390> on some systems). |
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510 | |
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511 | Stratus VOS is now supported. See F<README.vos>. |
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512 | |
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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 |
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 |
523 | |
524 | =head1 Modules and Pragmata |
525 | |
526 | =head2 New Modules |
527 | |
13a2d996 |
528 | =over 4 |
429b3afa |
529 | |
530 | =item B |
531 | |
9cde0e7f |
532 | Perl compiler and tools. See L<B>. |
429b3afa |
533 | |
534 | =item Data::Dumper |
535 | |
536 | A module to pretty print Perl data. See L<Data::Dumper>. |
537 | |
f3d48bde |
538 | =item Dumpvalue |
539 | |
540 | A module to dump perl values to the screen. See L<Dumpvalue>. |
541 | |
429b3afa |
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 |
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 | |
13a2d996 |
599 | =over 4 |
429b3afa |
600 | |
2eac2f99 |
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 |
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 |
611 | =item CGI |
612 | |
613 | CGI has been updated to version 2.42. |
614 | |
2eac2f99 |
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 |
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 |
630 | A little bit of radial trigonometry (cylindrical and spherical) added, |
631 | for example the great circle distance. |
632 | |
429b3afa |
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 |
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 |
655 | =item CPAN |
656 | |
9cde0e7f |
657 | See <perlmodinstall> and L<CPAN>. |
429b3afa |
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 |
668 | |
669 | =head1 Utility Changes |
670 | |
637e9122 |
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 |
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 |
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 |
683 | =head1 Documentation Changes |
684 | |
429b3afa |
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 |
688 | submit patches for perl. |
689 | |
9cde0e7f |
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 |
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 |
703 | =head1 New Diagnostics |
704 | |
13a2d996 |
705 | =over 4 |
429b3afa |
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 |
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 |
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 |
760 | =item Can't localize pseudo-hash element |
761 | |
c47ff5f1 |
762 | (F) You said something like C<< local $ar->{'key'} >>, where $ar is |
0ebe0038 |
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 |
c47ff5f1 |
765 | element directly -- C<< local $ar->[$ar->[0]{'key'}] >>. |
0ebe0038 |
766 | |
429b3afa |
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 |
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, $p || 'MyPackage'); |
429b3afa |
829 | |
830 | =item Illegal hex digit ignored |
831 | |
832 | (W) You may have tried to use a character other than 0 - 9 or A - F in a |
833 | hexadecimal number. Interpretation of the hexadecimal number stopped |
834 | before the illegal character. |
835 | |
836 | =item No such array field |
837 | |
838 | (F) You tried to access an array as a hash, but the field name used is |
839 | not defined. The hash at index 0 should map all valid field names to |
840 | array indices for that to work. |
841 | |
842 | =item No such field "%s" in variable %s of type %s |
843 | |
844 | (F) You tried to access a field of a typed variable where the type |
845 | does not know about the field name. The field names are looked up in |
846 | the %FIELDS hash in the type package at compile time. The %FIELDS hash |
847 | is usually set up with the 'fields' pragma. |
848 | |
849 | =item Out of memory during ridiculously large request |
850 | |
851 | (F) You can't allocate more than 2^31+"small amount" bytes. This error |
852 | is most likely to be caused by a typo in the Perl program. e.g., C<$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 |
913 | |
914 | =back |
915 | |
916 | |
917 | =head1 Obsolete Diagnostics |
918 | |
13a2d996 |
919 | =over 4 |
6cc33c6d |
920 | |
429b3afa |
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 |
926 | Removed because B<-e> doesn't use temporary files any more. |
927 | |
429b3afa |
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 |
933 | Removed because B<-e> doesn't use temporary files any more. |
934 | |
429b3afa |
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 |
940 | Removed because B<-e> doesn't use temporary files any more. |
941 | |
0f31cffe |
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 |
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 |
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 |
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 |
985 | from The Perl Porters. |
986 | |
987 | Send omissions or corrections to <F<perlbug@perl.com>>. |
988 | |
429b3afa |
989 | =cut |