| 1 | =head1 NAME |
| 2 | |
| 3 | perldelta - what's new for perl v5.6 (as of v5.005_64) |
| 4 | |
| 5 | =head1 DESCRIPTION |
| 6 | |
| 7 | This is an unsupported alpha release, meant for intrepid Perl developers |
| 8 | only. The included sources may not even build correctly on some platforms. |
| 9 | Subscribing to perl5-porters is the best way to monitor and contribute |
| 10 | to the progress of development releases (see www.perl.org for info). |
| 11 | |
| 12 | This document describes differences between the 5.005 release and this one. |
| 13 | |
| 14 | =head1 Incompatible Changes |
| 15 | |
| 16 | =head2 Perl Source Incompatibilities |
| 17 | |
| 18 | Beware that any new warnings that have been added or old ones |
| 19 | that have been enhanced are B<not> considered incompatible changes. |
| 20 | |
| 21 | Since all new warnings must be explicitly requested via the C<-w> |
| 22 | switch or the C<warnings> pragma, it is ultimately the programmer's |
| 23 | responsibility to ensure that warnings are enabled judiciously. |
| 24 | |
| 25 | =over 4 |
| 26 | |
| 27 | =item CHECK is a new keyword |
| 28 | |
| 29 | In addition to C<BEGIN>, C<INIT>, C<END>, C<DESTROY> and C<AUTOLOAD>, |
| 30 | subroutines named C<CHECK> are now special. These are queued up during |
| 31 | compilation and behave similar to END blocks, except they are called at |
| 32 | the end of compilation rather than at the end of execution. They cannot |
| 33 | be called directly. |
| 34 | |
| 35 | =item Treatment of list slices of undef has changed |
| 36 | |
| 37 | When taking a slice of a literal list (as opposed to a slice of |
| 38 | an array or hash), Perl used to return an empty list if the |
| 39 | result happened to be composed of all undef values. |
| 40 | |
| 41 | The new behavior is to produce an empty list if (and only if) |
| 42 | the original list was empty. Consider the following example: |
| 43 | |
| 44 | @a = (1,undef,undef,2)[2,1,2]; |
| 45 | |
| 46 | The old behavior would have resulted in @a having no elements. |
| 47 | The new behavior ensures it has three undefined elements. |
| 48 | |
| 49 | Note in particular that the behavior of slices of the following |
| 50 | cases remains unchanged: |
| 51 | |
| 52 | @a = ()[1,2]; |
| 53 | @a = (getpwent)[7,0]; |
| 54 | @a = (anything_returning_empty_list())[2,1,2]; |
| 55 | @a = @b[2,1,2]; |
| 56 | @a = @c{'a','b','c'}; |
| 57 | |
| 58 | See L<perldata>. |
| 59 | |
| 60 | =item Possibly changed pseudo-random number generator |
| 61 | |
| 62 | In 5.005_0x and earlier, perl's rand() function used the C library |
| 63 | rand(3) function. As of 5.005_52, Configure tests for drand48(), |
| 64 | random(), and rand() (in that order) and picks the first one it finds. |
| 65 | Perl programs that depend on reproducing a specific set of pseudo-random |
| 66 | numbers will now likely produce different output. You can use |
| 67 | C<sh Configure -Drandfunc=rand> to obtain the old behavior. |
| 68 | |
| 69 | =item Hashing function for hash keys has changed |
| 70 | |
| 71 | Perl hashes are not order preserving. The apparently random order |
| 72 | encountered when iterating on the contents of a hash is determined |
| 73 | by the hashing algorithm used. To improve the distribution of lower |
| 74 | bits in the hashed value, the algorithm has changed slightly as of |
| 75 | 5.005_52. When iterating over hashes, this may yield a random order |
| 76 | that is B<different> from that of previous versions. |
| 77 | |
| 78 | =item C<undef> fails on read only values |
| 79 | |
| 80 | Using the C<undef> operator on a readonly value (such as $1) has |
| 81 | the same effect as assigning C<undef> to the readonly value--it |
| 82 | throws an exception. |
| 83 | |
| 84 | =item Close-on-exec bit may be set on pipe() handles |
| 85 | |
| 86 | On systems that support a close-on-exec flag on filehandles, the |
| 87 | flag will be set for any handles created by pipe(), if that is |
| 88 | warranted by the value of $^F that may be in effect. Earlier |
| 89 | versions neglected to set the flag for handles created with |
| 90 | pipe(). See L<perlfunc/pipe> and L<perlvar/$^F>. |
| 91 | |
| 92 | =item Writing C<"$$1"> to mean C<"${$}1"> is unsupported |
| 93 | |
| 94 | Perl 5.004 deprecated the interpretation of C<$$1> and |
| 95 | similar within interpolated strings to mean C<$$ . "1">, |
| 96 | but still allowed it. |
| 97 | |
| 98 | In Perl 5.6 and later, C<"$$1"> always means C<"${$1}">. |
| 99 | |
| 100 | =item delete(), values() and C<\(%h)> operate on aliases to values, not copies |
| 101 | |
| 102 | delete(), each(), values() and hashes in a list context return the actual |
| 103 | values in the hash, instead of copies (as they used to in earlier |
| 104 | versions). Typical idioms for using these constructs copy the |
| 105 | returned values, but this can make a significant difference when |
| 106 | creating references to the returned values. |
| 107 | |
| 108 | Keys in the hash are still returned as copies when iterating on |
| 109 | a hash. |
| 110 | |
| 111 | =item vec(EXPR,OFFSET,BITS) enforces powers-of-two BITS |
| 112 | |
| 113 | vec() generates a run-time error if the BITS argument is not |
| 114 | a valid power-of-two integer. |
| 115 | |
| 116 | =item Text of some diagnostic output has changed |
| 117 | |
| 118 | Most references to internal Perl operations in diagnostics |
| 119 | have been changed to be more descriptive. This may be an |
| 120 | issue for programs that may incorrectly rely on the exact |
| 121 | text of diagnostics for proper functioning. |
| 122 | |
| 123 | =item C<%@> has been removed |
| 124 | |
| 125 | The undocumented special variable C<%@> that used to accumulate |
| 126 | "background" errors (such as those that happen in DESTROY()) |
| 127 | has been removed, because it could potentially result in memory |
| 128 | leaks. |
| 129 | |
| 130 | =item Parenthesized not() behaves like a list operator |
| 131 | |
| 132 | The C<not> operator now falls under the "if it looks like a function, |
| 133 | it behaves like a function" rule. |
| 134 | |
| 135 | As a result, the parenthesized form can be used with C<grep> and C<map>. |
| 136 | The following construct used to be a syntax error before, but it works |
| 137 | as expected now: |
| 138 | |
| 139 | grep not($_), @things; |
| 140 | |
| 141 | On the other hand, using C<not> with a literal list slice may not |
| 142 | work. The following previously allowed construct: |
| 143 | |
| 144 | print not (1,2,3)[0]; |
| 145 | |
| 146 | needs to be written with additional parentheses now: |
| 147 | |
| 148 | print not((1,2,3)[0]); |
| 149 | |
| 150 | The behavior remains unaffected when C<not> is not followed by parentheses. |
| 151 | |
| 152 | =item Semantics of bareword prototype C<(*)> have changed |
| 153 | |
| 154 | Arguments prototyped as C<*> will now be visible within the subroutine |
| 155 | as either a simple scalar or as a reference to a typeglob. Perl 5.005 |
| 156 | always coerced simple scalar arguments to a typeglob, which wasn't useful |
| 157 | in situations where the subroutine must distinguish between a simple |
| 158 | scalar and a typeglob. See L<perlsub/Prototypes>. |
| 159 | |
| 160 | =back |
| 161 | |
| 162 | =head2 C Source Incompatibilities |
| 163 | |
| 164 | =over 4 |
| 165 | |
| 166 | =item C<PERL_POLLUTE> |
| 167 | |
| 168 | Release 5.005 grandfathered old global symbol names by providing preprocessor |
| 169 | macros for extension source compatibility. As of release 5.6, these |
| 170 | preprocessor definitions are not available by default. You need to explicitly |
| 171 | compile perl with C<-DPERL_POLLUTE> to get these definitions. For |
| 172 | extensions still using the old symbols, this option can be |
| 173 | specified via MakeMaker: |
| 174 | |
| 175 | perl Makefile.PL POLLUTE=1 |
| 176 | |
| 177 | =item C<PERL_IMPLICIT_CONTEXT> |
| 178 | |
| 179 | PERL_IMPLICIT_CONTEXT is automatically enabled whenever Perl is built |
| 180 | with one of -Dusethreads, -Dusemultiplicity, or both. It is not |
| 181 | intended to be enabled by users at this time. |
| 182 | |
| 183 | This new build option provides a set of macros for all API functions |
| 184 | such that an implicit interpreter/thread context argument is passed to |
| 185 | every API function. As a result of this, something like C<sv_setsv(foo,bar)> |
| 186 | amounts to a macro invocation that actually translates to something like |
| 187 | C<Perl_sv_setsv(my_perl,foo,bar)>. While this is generally expected |
| 188 | to not have any significant source compatibility issues, the difference |
| 189 | between a macro and a real function call will need to be considered. |
| 190 | |
| 191 | This means that there B<is> a source compatibility issue as a result of |
| 192 | this if your extensions attempt to use pointers to any of the Perl API |
| 193 | functions. |
| 194 | |
| 195 | Note that the above issue is not relevant to the default build of |
| 196 | Perl, whose interfaces continue to match those of prior versions |
| 197 | (but subject to the other options described here). |
| 198 | |
| 199 | See L<perlguts/"The Perl API"> for detailed information on the |
| 200 | ramifications of building Perl using this option. |
| 201 | |
| 202 | =item C<PERL_POLLUTE_MALLOC> |
| 203 | |
| 204 | Enabling Perl's malloc in release 5.005 and earlier caused |
| 205 | the namespace of system versions of the malloc family of functions to |
| 206 | be usurped by the Perl versions, since by default they used the |
| 207 | same names. |
| 208 | |
| 209 | Besides causing problems on platforms that do not allow these functions to |
| 210 | be cleanly replaced, this also meant that the system versions could not |
| 211 | be called in programs that used Perl's malloc. Previous versions of Perl |
| 212 | have allowed this behaviour to be suppressed with the HIDEMYMALLOC and |
| 213 | EMBEDMYMALLOC preprocessor definitions. |
| 214 | |
| 215 | As of release 5.6, Perl's malloc family of functions have default names |
| 216 | distinct from the system versions. You need to explicitly compile perl with |
| 217 | C<-DPERL_POLLUTE_MALLOC> to get the older behaviour. HIDEMYMALLOC |
| 218 | and EMBEDMYMALLOC have no effect, since the behaviour they enabled is now |
| 219 | the default. |
| 220 | |
| 221 | Note that these functions do B<not> constitute Perl's memory allocation API. |
| 222 | See L<perlguts/"Memory Allocation"> for further information about that. |
| 223 | |
| 224 | =back |
| 225 | |
| 226 | =head2 Compatible C Source API Changes |
| 227 | |
| 228 | =over |
| 229 | |
| 230 | =item C<PATCHLEVEL> is now C<PERL_VERSION> |
| 231 | |
| 232 | The cpp macros C<PERL_REVISION>, C<PERL_VERSION>, and C<PERL_SUBVERSION> |
| 233 | are now available by default from perl.h, and reflect the base revision, |
| 234 | patchlevel, and subversion respectively. C<PERL_REVISION> had no |
| 235 | prior equivalent, while C<PERL_VERSION> and C<PERL_SUBVERSION> were |
| 236 | previously available as C<PATCHLEVEL> and C<SUBVERSION>. |
| 237 | |
| 238 | The new names cause less pollution of the B<cpp> namespace and reflect what |
| 239 | the numbers have come to stand for in common practice. For compatibility, |
| 240 | the old names are still supported when F<patchlevel.h> is explicitly |
| 241 | included (as required before), so there is no source incompatibility |
| 242 | from the change. |
| 243 | |
| 244 | =item Support for C++ exceptions |
| 245 | |
| 246 | change#3386, also needs perlguts documentation |
| 247 | [TODO - Chip Salzenberg <chip@perlsupport.com>] |
| 248 | |
| 249 | =back |
| 250 | |
| 251 | =head2 Binary Incompatibilities |
| 252 | |
| 253 | In general, the default build of this release is expected to be binary |
| 254 | compatible for extensions built with the 5.005 release or its maintenance |
| 255 | versions. However, specific platforms may have broken binary compatibility |
| 256 | due to changes in the defaults used in hints files. Therefore, please be |
| 257 | sure to always check the platform-specific README files for any notes to |
| 258 | the contrary. |
| 259 | |
| 260 | The usethreads or usemultiplicity builds are B<not> binary compatible |
| 261 | with the corresponding builds in 5.005. |
| 262 | |
| 263 | On platforms that require an explicit list of exports (AIX, OS/2 and Windows, |
| 264 | among others), purely internal symbols such as parser functions and the |
| 265 | run time opcodes are not exported by default. Perl 5.005 used to export |
| 266 | all functions irrespective of whether they were considered part of the |
| 267 | public API or not. |
| 268 | |
| 269 | For the full list of public API functions, see L<perlapi>. |
| 270 | |
| 271 | =head1 Installation and Configuration Improvements |
| 272 | |
| 273 | =head2 -Dusethreads means something different |
| 274 | |
| 275 | WARNING: Support for threads continues to be an experimental feature. |
| 276 | Interfaces and implementation are subject to sudden and drastic changes. |
| 277 | |
| 278 | The -Dusethreads flag now enables the experimental interpreter-based thread |
| 279 | support by default. To get the flavor of experimental threads that was in |
| 280 | 5.005 instead, you need to ask for -Duse5005threads. |
| 281 | |
| 282 | As of v5.5.640, interpreter-threads support is still lacking a way to |
| 283 | create new threads from Perl (i.e., C<use Thread;> will not work with |
| 284 | interpreter threads). C<use Thread;> continues to be available when you |
| 285 | ask for -Duse5005threads, bugs and all. |
| 286 | |
| 287 | =head2 Perl's version numbering has changed |
| 288 | |
| 289 | Beginning with Perl version 5.6, the version number convention has been |
| 290 | changed to a "dotted tuple" scheme that is more commonly found in open |
| 291 | source projects. |
| 292 | |
| 293 | Maintenance versions of v5.6.0 will be released as v5.6.1, v5.6.2 etc. |
| 294 | The next development series following v5.6 will be numbered v5.7.x, |
| 295 | beginning with v5.7.0, and the next major production release following |
| 296 | v5.6 will be v5.8. |
| 297 | |
| 298 | The v1.2.3 syntax is also now legal in Perl. See L<Support for version tuples> |
| 299 | for more on that. |
| 300 | |
| 301 | To cope with the new versioning system's use of at least three significant |
| 302 | digits for each version component, the method used for incrementing the |
| 303 | subversion number has also changed slightly. We assume that versions older |
| 304 | than v5.6 have been incrementing the subversion component in multiples of |
| 305 | 10. Versions after v5.6 will increment them by 1. Thus, using the new |
| 306 | notation, 5.005_03 is the same as v5.5.30, and the first maintenance |
| 307 | version following v5.6 will be v5.6.1, which amounts to a floating point |
| 308 | value of 5.006_001). |
| 309 | |
| 310 | =head2 New Configure flags |
| 311 | |
| 312 | The following new flags may be enabled on the Configure command line |
| 313 | by running Configure with C<-Dflag>. |
| 314 | |
| 315 | usemultiplicity |
| 316 | use5005threads |
| 317 | |
| 318 | uselongdouble |
| 319 | usemorebits |
| 320 | uselargefiles |
| 321 | |
| 322 | =head2 -Dusethreads and -Duse64bits now more daring |
| 323 | |
| 324 | The Configure options enabling the use of threads and the use of |
| 325 | 64-bitness are now more daring in the sense that they no more have an |
| 326 | explicit list of operating systems of known threads/64-bit |
| 327 | capabilities. In other words: if your operating system has the |
| 328 | necessary APIs and datatypes, you should be able just to go ahead and |
| 329 | use them, for threads by Configure -Dusethreads, and for 64 bits |
| 330 | either explicitly by Configure -Duse64bits or implicitly if your |
| 331 | system has 64 bit wide datatypes. See also L<"64-bit support">. |
| 332 | |
| 333 | =head2 Long Doubles |
| 334 | |
| 335 | Some platforms have "long doubles", floating point numbers of even |
| 336 | larger range than ordinary "doubles". To enable using long doubles for |
| 337 | Perl's scalars, use -Duselongdouble. |
| 338 | |
| 339 | =head2 -Dusemorebits |
| 340 | |
| 341 | You can enable both -Duse64bits and -Dlongdouble by -Dusemorebits. |
| 342 | See also L<"64-bit support">. |
| 343 | |
| 344 | =head2 -Duselargefiles |
| 345 | |
| 346 | Some platforms support large files, files larger than two gigabytes. |
| 347 | See L<"Large file support"> for more information. |
| 348 | |
| 349 | =head2 installusrbinperl |
| 350 | |
| 351 | You can use "Configure -Uinstallusrbinperl" which causes installperl |
| 352 | to skip installing perl also as /usr/bin/perl. This is useful if you |
| 353 | prefer not to modify /usr/bin for some reason or another but harmful |
| 354 | because many scripts assume to find Perl in /usr/bin/perl. |
| 355 | |
| 356 | =head2 SOCKS support |
| 357 | |
| 358 | You can use "Configure -Dusesocks" which causes Perl to probe |
| 359 | for the SOCKS (v5, not v4) proxy protocol library, |
| 360 | http://www.socks.nec.com/ |
| 361 | |
| 362 | =head2 C<-A> flag |
| 363 | |
| 364 | You can "post-edit" the Configure variables using the Configure C<-A> |
| 365 | flag. The editing happens immediately after the platform specific |
| 366 | hints files have been processed but before the actual configuration |
| 367 | process starts. Run C<Configure -h> to find out the full C<-A> syntax. |
| 368 | |
| 369 | =head2 Enhanced Installation Directories |
| 370 | |
| 371 | The installation structure has been enriched to improve the support for |
| 372 | maintaining multiple versions of perl, to provide locations for |
| 373 | vendor-supplied modules and scripts, and to ease maintenance of |
| 374 | locally-added modules and scripts. See the section on Installation |
| 375 | Directories in the INSTALL file for complete details. For most users |
| 376 | building and installing from source, the defaults should be fine. |
| 377 | |
| 378 | =head1 Core Changes |
| 379 | |
| 380 | =head2 Unicode and UTF-8 support |
| 381 | |
| 382 | Perl can optionally use UTF-8 as its internal representation for character |
| 383 | strings. The C<utf8> and C<byte> pragmas are used to control this support |
| 384 | in the current lexical scope. See L<perlunicode>, L<utf8> and L<byte> for |
| 385 | more information. |
| 386 | |
| 387 | =head2 Interpreter cloning, threads, and concurrency |
| 388 | |
| 389 | WARNING: This is an experimental feature in a pre-alpha state. Use |
| 390 | at your own risk. |
| 391 | |
| 392 | Perl 5.005_63 introduces the beginnings of support for running multiple |
| 393 | interpreters concurrently in different threads. In conjunction with |
| 394 | the perl_clone() API call, which can be used to selectively duplicate |
| 395 | the state of any given interpreter, it is possible to compile a |
| 396 | piece of code once in an interpreter, clone that interpreter |
| 397 | one or more times, and run all the resulting interpreters in distinct |
| 398 | threads. |
| 399 | |
| 400 | On Windows, this feature is used to emulate fork() at the interpreter |
| 401 | level. See L<perlfork>. |
| 402 | |
| 403 | This feature is still in evolution. It is eventually meant to be used |
| 404 | to selectively clone a subroutine and data reachable from that |
| 405 | subroutine in a separate interpreter and run the cloned subroutine |
| 406 | in a separate thread. Since there is no shared data between the |
| 407 | interpreters, little or no locking will be needed (unless parts of |
| 408 | the symbol table are explicitly shared). This is obviously intended |
| 409 | to be an easy-to-use replacement for the existing threads support. |
| 410 | |
| 411 | Support for cloning interpreters and interpreter concurrency can be |
| 412 | enabled using the -Dusethreads Configure option (see win32/Makefile for |
| 413 | how to enable it on Windows.) The resulting perl executable will be |
| 414 | functionally identical to one that was built with -Dmultiplicity, but |
| 415 | the perl_clone() API call will only be available in the former. |
| 416 | |
| 417 | -Dusethreads enables, the cpp macros USE_ITHREADS by default, which enables |
| 418 | Perl source code changes that provide a clear separation between the op tree |
| 419 | and the data it operates with. The former is considered immutable, and can |
| 420 | therefore be shared between an interpreter and all of its clones, while the |
| 421 | latter is considered local to each interpreter, and is therefore copied for |
| 422 | each clone. |
| 423 | |
| 424 | Note that building Perl with the -Dusemultiplicity Configure option |
| 425 | is adequate if you wish to run multiple B<independent> interpreters |
| 426 | concurrently in different threads. -Dusethreads only provides the |
| 427 | additional functionality of the perl_clone() API call and other |
| 428 | support for running B<cloned> interpreters concurrently. |
| 429 | |
| 430 | [XXX TODO - the Compiler backends may be broken when USE_ITHREADS is |
| 431 | enabled.] |
| 432 | |
| 433 | =head2 Lexically scoped warning categories |
| 434 | |
| 435 | You can now control the granularity of warnings emitted by perl at a finer |
| 436 | level using the C<use warnings> pragma. See L<warnings> and L<perllexwarn> |
| 437 | for details. |
| 438 | |
| 439 | =head2 Lvalue subroutines |
| 440 | |
| 441 | WARNING: This is an experimental feature. |
| 442 | |
| 443 | change#4081 |
| 444 | [TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>, |
| 445 | Tuomas Lukka <lukka@iki.fi>)] |
| 446 | |
| 447 | =head2 "our" declarations |
| 448 | |
| 449 | An "our" declaration introduces a value that can be best understood |
| 450 | as a lexically scoped symbolic alias to a global variable in the |
| 451 | package that was current where the variable was declared. This is |
| 452 | mostly useful as an alternative to the C<vars> pragma, but also provides |
| 453 | the opportunity to introduce typing and other attributes for such |
| 454 | variables. See L<perlfunc/our>. |
| 455 | |
| 456 | =head2 Support for version tuples |
| 457 | |
| 458 | Literals of the form v1.2.3.4 are now parsed as the utf8 string |
| 459 | C<"\x{1}\x{2}\x{3}\x{4}">. This allows comparing version numbers using |
| 460 | regular string comparison operators C<eq>, C<ne>, C<lt>, C<gt> etc. |
| 461 | |
| 462 | These "dotted tuples" are dual-valued. They are both strings of utf8 |
| 463 | characters, and floating point numbers. Thus v1.2.3.4 has the string |
| 464 | value C<"\x{1}\x{2}\x{3}\x{4}"> and the numeric value 1.002_003_004. |
| 465 | As another example, v5.5.640 has the string value C<"\x{5}\x{5}\x{280}"> |
| 466 | (remember 280 hexadecimal is 640 decimal) and the numeric value |
| 467 | 5.005_64. |
| 468 | |
| 469 | In conjunction with the new C<$^V> magic variable (which contains |
| 470 | the perl version in this format), such literals can be used to |
| 471 | check if you're running a particular version of Perl. |
| 472 | |
| 473 | if ($^V and $^V gt v5.5.640) { |
| 474 | # new style version numbers are supported |
| 475 | } |
| 476 | |
| 477 | C<require> and C<use> also support such literals: |
| 478 | |
| 479 | require v5.6.0; # croak if $^V lt v5.6.0 |
| 480 | use v5.6.0; # same, but croaks at compile-time |
| 481 | |
| 482 | C<sprintf> and C<printf> support the Perl-specific format type C<%v> |
| 483 | to print arbitrary strings as dotted tuples. |
| 484 | |
| 485 | printf "v%v", $^V; # prints current version, such as "v5.5.650" |
| 486 | |
| 487 | =head2 Weak references |
| 488 | |
| 489 | WARNING: This is an experimental feature. |
| 490 | |
| 491 | In previous versions of Perl, you couldn't cache objects so as |
| 492 | to allow them to be deleted if the last reference from outside |
| 493 | the cache is deleted. The reference in the cache would hold a |
| 494 | reference count on the object and the objects would never be |
| 495 | destroyed. |
| 496 | |
| 497 | Another familiar problem is with circular references. When an |
| 498 | object references itself, its reference count would never go |
| 499 | down to zero, and it would not get destroyed until the program |
| 500 | is about to exit. |
| 501 | |
| 502 | Weak references solve this by allowing you to "weaken" any |
| 503 | reference, that is, make it not count towards the reference count. |
| 504 | When the last non-weak reference to an object is deleted, the object |
| 505 | is destroyed and all the weak references to the object are |
| 506 | automatically undef-ed. |
| 507 | |
| 508 | To use this feature, you need the WeakRef package from CPAN, which |
| 509 | contains additional documentation. |
| 510 | |
| 511 | change#3385, also need perlguts documentation |
| 512 | [TODO - Tuomas Lukka <lukka@iki.fi>] |
| 513 | |
| 514 | =head2 File globbing implemented internally |
| 515 | |
| 516 | WARNING: This is currently an experimental feature. Interfaces and |
| 517 | implementation are likely to change. |
| 518 | |
| 519 | Perl now uses the File::Glob implementation of the glob() operator |
| 520 | automatically. This avoids using an external csh process and the |
| 521 | problems associated with it. |
| 522 | |
| 523 | =head2 Binary numbers supported |
| 524 | |
| 525 | Binary numbers are now supported as literals, in s?printf formats, and |
| 526 | C<oct()>: |
| 527 | |
| 528 | $answer = 0b101010; |
| 529 | printf "The answer is: %b\n", oct("0b101010"); |
| 530 | |
| 531 | =head2 Some arrows may be omitted in calls through references |
| 532 | |
| 533 | Perl now allows the arrow to be omitted in many constructs |
| 534 | involving subroutine calls through references. For example, |
| 535 | C<$foo[10]-E<gt>('foo')> may now be written C<$foo[10]('foo')>. |
| 536 | This is rather similar to how the arrow may be omitted from |
| 537 | C<$foo[10]-E<gt>{'foo'}>. Note however, that the arrow is still |
| 538 | required for C<foo(10)-E<gt>('bar')>. |
| 539 | |
| 540 | =head2 exists() is supported on subroutine names |
| 541 | |
| 542 | The exists() builtin now works on subroutine names. A subroutine |
| 543 | is considered to exist if it has been declared (even if implicitly). |
| 544 | See L<perlfunc/exists> for examples. |
| 545 | |
| 546 | =head2 exists() and delete() are supported on array elements |
| 547 | |
| 548 | The exists() and delete() builtins now work on simple arrays as well. |
| 549 | The behavior is similar to that on hash elements. |
| 550 | |
| 551 | exists() can be used to check whether an array element has been |
| 552 | initialized. This avoids autovivifying array elements that don't exist. |
| 553 | If the array is tied, the EXISTS() method in the corresponding tied |
| 554 | package will be invoked. |
| 555 | |
| 556 | delete() may be used to remove an element from the array and return |
| 557 | it. The array element at that position returns to its unintialized |
| 558 | state, so that testing for the same element with exists() will return |
| 559 | false. If the element happens to be the one at the end, the size of |
| 560 | the array also shrinks up to the highest element that tests true for |
| 561 | exists(), or 0 if none such is found. If the array is tied, the DELETE() |
| 562 | method in the corresponding tied package will be invoked. |
| 563 | |
| 564 | See L<perlfunc/exists> and L<perlfunc/delete> for examples. |
| 565 | |
| 566 | =head2 syswrite() ease-of-use |
| 567 | |
| 568 | The length argument of C<syswrite()> has become optional. |
| 569 | |
| 570 | =head2 File and directory handles can be autovivified |
| 571 | |
| 572 | Similar to how constructs such as C<$x-E<gt>[0]> autovivify a reference, |
| 573 | handle constructors (open(), opendir(), pipe(), socketpair(), sysopen(), |
| 574 | socket(), and accept()) now autovivify a file or directory handle |
| 575 | if the handle passed to them is an uninitialized scalar variable. This |
| 576 | allows the constructs such as C<open(my $fh, ...)> and C<open(local $fh,...)> |
| 577 | to be used to create filehandles that will conveniently be closed |
| 578 | automatically when the scope ends, provided there are no other references |
| 579 | to them. This largely eliminates the need for typeglobs when opening |
| 580 | filehandles that must be passed around, as in the following example: |
| 581 | |
| 582 | sub myopen { |
| 583 | open my $fh, "@_" |
| 584 | or die "Can't open '@_': $!"; |
| 585 | return $fh; |
| 586 | } |
| 587 | |
| 588 | { |
| 589 | my $f = myopen("</etc/motd"); |
| 590 | print <$f>; |
| 591 | # $f implicitly closed here |
| 592 | } |
| 593 | |
| 594 | [TODO - this idiom needs more pod penetration] |
| 595 | |
| 596 | =head2 64-bit support |
| 597 | |
| 598 | All platforms that have 64-bit integers either (a) natively as longs |
| 599 | or ints (b) via special compiler flags (c) using long long are able to |
| 600 | use "quads" (64-integers) as follows: |
| 601 | |
| 602 | =over 4 |
| 603 | |
| 604 | =item * |
| 605 | |
| 606 | constants (decimal, hexadecimal, octal, binary) in the code |
| 607 | |
| 608 | =item * |
| 609 | |
| 610 | arguments to oct() and hex() |
| 611 | |
| 612 | =item * |
| 613 | |
| 614 | arguments to print(), printf() and sprintf() (flag prefixes ll, L, q) |
| 615 | |
| 616 | =item * |
| 617 | |
| 618 | printed as such |
| 619 | |
| 620 | =item * |
| 621 | |
| 622 | pack() and unpack() "q" and "Q" formats |
| 623 | |
| 624 | =item * |
| 625 | |
| 626 | in basic arithmetics: + - * / % |
| 627 | |
| 628 | =item * |
| 629 | |
| 630 | vec() (but see the below note about bit arithmetics) |
| 631 | |
| 632 | =back |
| 633 | |
| 634 | Note that unless you have the case (a) you will have to configure |
| 635 | and compile Perl using the -Duse64bits Configure flag. |
| 636 | |
| 637 | Unfortunately bit arithmetics (&, |, ^, ~, <<, >>) for numbers are not |
| 638 | 64-bit clean, they are explictly forced to be 32-bit because of |
| 639 | tangled backward compatibility issues. This limitation is subject to |
| 640 | change. Bit arithmetics for bit vector scalars (created by vec()) are |
| 641 | not limited in their width. |
| 642 | |
| 643 | Last but not least: note that due to Perl's habit of always using |
| 644 | floating point numbers the quads are still not true integers. |
| 645 | When quads overflow their limits (0...18_446_744_073_709_551_615 unsigned, |
| 646 | -9_223_372_036_854_775_808...9_223_372_036_854_775_807 signed), they |
| 647 | are silently promoted to floating point numbers, after which they will |
| 648 | start losing precision (their lower digits). |
| 649 | |
| 650 | =head2 Large file support |
| 651 | |
| 652 | If you have filesystems that support "large files" (files larger than |
| 653 | 2 gigabytes), you may now also be able to create and access them from |
| 654 | Perl. You have to use Configure -Duselargefiles. Turning on the |
| 655 | large file support turns on also the 64-bit support on many platforms. |
| 656 | Beware that unless your filesystem also supports "sparse files" seeking |
| 657 | to umpteen petabytes may be unadvisable. |
| 658 | |
| 659 | Note that in addition to requiring a proper file system to do large |
| 660 | files you may also need to adjust your per-process (or your |
| 661 | per-system, or per-process-group, or per-user-group) maximum filesize |
| 662 | limits before running Perl scripts that try to handle large files, |
| 663 | especially if you intend to write such files. |
| 664 | |
| 665 | Finally, in addition to your process/process group maximum filesize |
| 666 | limits, you may have quota limits on your filesystems that stop you |
| 667 | (your user id or your user group id) from using large files. |
| 668 | |
| 669 | Adjusting your process/user/group/file system/operating system limits |
| 670 | is outside the scope of Perl core language. For process limits, you |
| 671 | may try increasing the limits using your shell's limits/limit/ulimit |
| 672 | command before running Perl. The BSD::Resource extension (not |
| 673 | included with the standard Perl distribution) may also be of use, it |
| 674 | offers the getrlimit/setrlimit interface that can be used to adjust |
| 675 | process resource usage limits, including the maximum filesize limit. |
| 676 | |
| 677 | =head2 Long doubles |
| 678 | |
| 679 | In some systems you may be able to use long doubles to enhance the |
| 680 | range and precision of your double precision floating point numbers |
| 681 | (that is, Perl's numbers). Use Configure -Duselongdouble to enable |
| 682 | this support (if it is available). |
| 683 | |
| 684 | =head2 "more bits" |
| 685 | |
| 686 | You can "Configure -Dusemorebits" to turn on both the 64-bit support |
| 687 | and the long double support. |
| 688 | |
| 689 | =head2 Enhanced support for sort() subroutines |
| 690 | |
| 691 | Perl subroutines with a prototype of C<($$)> and XSUBs in general can |
| 692 | now be used as sort subroutines. In either case, the two elements to |
| 693 | be compared are passed as normal parameters in @_. See L<perlfunc/sort>. |
| 694 | |
| 695 | For unprototyped sort subroutines, the historical behavior of passing |
| 696 | the elements to be compared as the global variables $a and $b remains |
| 697 | unchanged. |
| 698 | |
| 699 | =head2 Better syntax checks on parenthesized unary operators |
| 700 | |
| 701 | Expressions such as: |
| 702 | |
| 703 | print defined(&foo,&bar,&baz); |
| 704 | print uc("foo","bar","baz"); |
| 705 | undef($foo,&bar); |
| 706 | |
| 707 | used to be accidentally allowed in earlier versions, and produced |
| 708 | unpredictable behaviour. Some produced ancillary warnings |
| 709 | when used in this way; others silently did the wrong thing. |
| 710 | |
| 711 | The parenthesized forms of most unary operators that expect a single |
| 712 | argument now ensure that they are not called with more than one |
| 713 | argument, making the cases shown above syntax errors. The usual |
| 714 | behaviour of: |
| 715 | |
| 716 | print defined &foo, &bar, &baz; |
| 717 | print uc "foo", "bar", "baz"; |
| 718 | undef $foo, &bar; |
| 719 | |
| 720 | remains unchanged. See L<perlop>. |
| 721 | |
| 722 | =head2 POSIX character class syntax [: :] supported |
| 723 | |
| 724 | For example to match alphabetic characters use /[[:alpha:]]/. |
| 725 | See L<perlre> for details. |
| 726 | |
| 727 | =head2 Improved C<qw//> operator |
| 728 | |
| 729 | The C<qw//> operator is now evaluated at compile time into a true list |
| 730 | instead of being replaced with a run time call to C<split()>. This |
| 731 | removes the confusing misbehaviour of C<qw//> in scalar context, which |
| 732 | had inherited that behaviour from split(). |
| 733 | |
| 734 | Thus: |
| 735 | |
| 736 | $foo = ($bar) = qw(a b c); print "$foo|$bar\n"; |
| 737 | |
| 738 | now correctly prints "3|a", instead of "2|a". |
| 739 | |
| 740 | =head2 pack() format 'Z' supported |
| 741 | |
| 742 | The new format type 'Z' is useful for packing and unpacking null-terminated |
| 743 | strings. See L<perlfunc/"pack">. |
| 744 | |
| 745 | =head2 pack() format modifier '!' supported |
| 746 | |
| 747 | The new format type modifier '!' is useful for packing and unpacking |
| 748 | native shorts, ints, and longs. See L<perlfunc/"pack">. |
| 749 | |
| 750 | =head2 pack() and unpack() support counted strings |
| 751 | |
| 752 | The template character '/' can be used to specify a counted string |
| 753 | type to be packed or unpacked. See L<perlfunc/"pack">. |
| 754 | |
| 755 | =head2 Comments in pack() templates |
| 756 | |
| 757 | The '#' character in a template introduces a comment up to |
| 758 | end of the line. This facilitates documentation of pack() |
| 759 | templates. |
| 760 | |
| 761 | =head2 $^X variables may now have names longer than one character |
| 762 | |
| 763 | Formerly, $^X was synonymous with ${"\cX"}, but $^XY was a syntax |
| 764 | error. Now variable names that begin with a control character may be |
| 765 | arbitrarily long. However, for compatibility reasons, these variables |
| 766 | I<must> be written with explicit braces, as C<${^XY}> for example. |
| 767 | C<${^XYZ}> is synonymous with ${"\cXYZ"}. Variable names with more |
| 768 | than one control character, such as C<${^XY^Z}>, are illegal. |
| 769 | |
| 770 | The old syntax has not changed. As before, `^X' may be either a |
| 771 | literal control-X character or the two-character sequence `caret' plus |
| 772 | `X'. When braces are omitted, the variable name stops after the |
| 773 | control character. Thus C<"$^XYZ"> continues to be synonymous with |
| 774 | C<$^X . "YZ"> as before. |
| 775 | |
| 776 | As before, lexical variables may not have names beginning with control |
| 777 | characters. As before, variables whose names begin with a control |
| 778 | character are always forced to be in package `main'. All such variables |
| 779 | are reserved for future extensions, except those that begin with |
| 780 | C<^_>, which may be used by user programs and are guaranteed not to |
| 781 | acquire special meaning in any future version of Perl. |
| 782 | |
| 783 | =head2 C<use attrs> implicit in subroutine attributes |
| 784 | |
| 785 | Formerly, if you wanted to mark a subroutine as being a method call or |
| 786 | as requiring an automatic lock() when it is entered, you had to declare |
| 787 | that with a C<use attrs> pragma in the body of the subroutine. |
| 788 | That can now be accomplished with declaration syntax, like this: |
| 789 | |
| 790 | sub mymethod : locked method ; |
| 791 | ... |
| 792 | sub mymethod : locked method { |
| 793 | ... |
| 794 | } |
| 795 | |
| 796 | sub othermethod :locked :method ; |
| 797 | ... |
| 798 | sub othermethod :locked :method { |
| 799 | ... |
| 800 | } |
| 801 | |
| 802 | |
| 803 | (Note how only the first C<:> is mandatory, and whitespace surrounding |
| 804 | the C<:> is optional.) |
| 805 | |
| 806 | F<AutoSplit.pm> and F<SelfLoader.pm> have been updated to keep the attributes |
| 807 | with the stubs they provide. See L<attributes>. |
| 808 | |
| 809 | =head2 Regular expression improvements |
| 810 | |
| 811 | change#2827,2373,2372,2365,1813,1800,4112,4158,4215,4301 |
| 812 | [TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>] |
| 813 | |
| 814 | =head2 Overloading improvements |
| 815 | |
| 816 | change#2150 |
| 817 | [TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>] |
| 818 | |
| 819 | =head2 open() with more than two arguments |
| 820 | |
| 821 | [TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>] |
| 822 | |
| 823 | =head2 Support for interpolating named characters |
| 824 | |
| 825 | change#4052 |
| 826 | [TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>] |
| 827 | |
| 828 | =head2 Experimental support for user-hooks in @INC |
| 829 | |
| 830 | [TODO - Ken Fox <kfox@ford.com>] |
| 831 | |
| 832 | =head2 C<require> and C<do> may be overridden |
| 833 | |
| 834 | C<require> and C<do 'file'> operations may be overridden locally |
| 835 | by importing subroutines of the same name into the current package |
| 836 | (or globally by importing them into the CORE::GLOBAL:: namespace). |
| 837 | Overriding C<require> will also affect C<use>, provided the override |
| 838 | is visible at compile-time. |
| 839 | See L<perlsub/"Overriding Built-in Functions">. |
| 840 | |
| 841 | =head2 New variable $^C reflects C<-c> switch |
| 842 | |
| 843 | C<$^C> has a boolean value that reflects whether perl is being run |
| 844 | in compile-only mode (i.e. via the C<-c> switch). Since |
| 845 | BEGIN blocks are executed under such conditions, this variable |
| 846 | enables perl code to determine whether actions that make sense |
| 847 | only during normal running are warranted. See L<perlvar>. |
| 848 | |
| 849 | =head2 New variable $^V contains Perl version in v5.6.0 format |
| 850 | |
| 851 | C<$^V> contains the Perl version number as a version tuple that |
| 852 | can be used in string or numeric comparisons. See |
| 853 | C<Support for version tuples> for an example. |
| 854 | |
| 855 | =head2 Optional Y2K warnings |
| 856 | |
| 857 | If Perl is built with the cpp macro C<PERL_Y2KWARN> defined, |
| 858 | it emits optional warnings when concatenating the number 19 |
| 859 | with another number. |
| 860 | |
| 861 | This behavior must be specifically enabled when running Configure. |
| 862 | See L<INSTALL> and L<README.Y2K>. |
| 863 | |
| 864 | =head1 Significant bug fixes |
| 865 | |
| 866 | =head2 E<lt>HANDLEE<gt> on empty files |
| 867 | |
| 868 | With C<$/> set to C<undef>, "slurping" an empty file returns a string of |
| 869 | zero length (instead of C<undef>, as it used to) the first time the |
| 870 | HANDLE is read after C<$/> is set to C<undef>. Further reads yield |
| 871 | C<undef>. |
| 872 | |
| 873 | This means that the following will append "foo" to an empty file (it used |
| 874 | to do nothing): |
| 875 | |
| 876 | perl -0777 -pi -e 's/^/foo/' empty_file |
| 877 | |
| 878 | The behaviour of: |
| 879 | |
| 880 | perl -pi -e 's/^/foo/' empty_file |
| 881 | |
| 882 | is unchanged (it continues to leave the file empty). |
| 883 | |
| 884 | =head2 C<eval '...'> improvements |
| 885 | |
| 886 | Line numbers (as reflected by caller() and most diagnostics) within |
| 887 | C<eval '...'> were often incorrect when here documents were involved. |
| 888 | This has been corrected. |
| 889 | |
| 890 | Lexical lookups for variables appearing in C<eval '...'> within |
| 891 | functions that were themselves called within an C<eval '...'> were |
| 892 | searching the wrong place for lexicals. The lexical search now |
| 893 | correctly ends at the subroutine's block boundary. |
| 894 | |
| 895 | Parsing of here documents used to be flawed when they appeared as |
| 896 | the replacement expression in C<eval 's/.../.../e'>. This has |
| 897 | been fixed. |
| 898 | |
| 899 | =head2 All compilation errors are true errors |
| 900 | |
| 901 | Some "errors" encountered at compile time were by neccessity |
| 902 | generated as warnings followed by eventual termination of the |
| 903 | program. This enabled more such errors to be reported in a |
| 904 | single run, rather than causing a hard stop at the first error |
| 905 | that was encountered. |
| 906 | |
| 907 | The mechanism for reporting such errors has been reimplemented |
| 908 | to queue compile-time errors and report them at the end of the |
| 909 | compilation as true errors rather than as warnings. This fixes |
| 910 | cases where error messages leaked through in the form of warnings |
| 911 | when code was compiled at run time using C<eval STRING>, and |
| 912 | also allows such errors to be reliably trapped using __DIE__ hooks. |
| 913 | |
| 914 | =head2 Automatic flushing of output buffers |
| 915 | |
| 916 | fork(), exec(), system(), qx//, and pipe open()s now flush buffers |
| 917 | of all files opened for output when the operation |
| 918 | was attempted. This mostly eliminates confusing |
| 919 | buffering mishaps suffered by users unaware of how Perl internally |
| 920 | handles I/O. |
| 921 | |
| 922 | =head2 Better diagnostics on meaningless filehandle operations |
| 923 | |
| 924 | Constructs such as C<open(E<lt>FHE<gt>)> and C<close(E<lt>FHE<gt>)> |
| 925 | are compile time errors. Attempting to read from filehandles that |
| 926 | were opened only for writing will now produce warnings (just as |
| 927 | writing to read-only filehandles does). |
| 928 | |
| 929 | =head2 Where possible, buffered data discarded from duped input filehandle |
| 930 | |
| 931 | C<open(NEW, "E<lt>&OLD")> now attempts to discard any data that |
| 932 | was previously read and buffered in C<OLD> before duping the handle. |
| 933 | On platforms where doing this is allowed, the next read operation |
| 934 | on C<NEW> will return the same data as the corresponding operation |
| 935 | on C<OLD>. Formerly, it would have returned the data from the start |
| 936 | of the following disk block instead. |
| 937 | |
| 938 | =head2 eof() has the same old magic as <> |
| 939 | |
| 940 | C<eof()> would return true if no attempt to read from C<E<lt>E<gt>> had |
| 941 | yet been made. C<eof()> has been changed to have a little magic of its |
| 942 | own, it now opens the C<E<lt>E<gt>> files. |
| 943 | |
| 944 | =head2 system(), backticks and pipe open now reflect exec() failure |
| 945 | |
| 946 | On Unix and similar platforms, system(), qx() and open(FOO, "cmd |") |
| 947 | etc., are implemented via fork() and exec(). When the underlying |
| 948 | exec() fails, earlier versions did not report the error properly, |
| 949 | since the exec() happened to be in a different process. |
| 950 | |
| 951 | The child process now communicates with the parent about the |
| 952 | error in launching the external command, which allows these |
| 953 | constructs to return with their usual error value and set $!. |
| 954 | |
| 955 | =head2 Implicitly closed filehandles are safer |
| 956 | |
| 957 | Sometimes implicitly closed filehandles (as when they are localized, |
| 958 | and Perl automatically closes them on exiting the scope) could |
| 959 | inadvertently set $? or $!. This has been corrected. |
| 960 | |
| 961 | =head2 C<(\$)> prototype and C<$foo{a}> |
| 962 | |
| 963 | An scalar reference prototype now correctly allows a hash or |
| 964 | array element in that slot. |
| 965 | |
| 966 | =head2 Pseudo-hashes work better |
| 967 | |
| 968 | Dereferencing some types of reference values in a pseudo-hash, |
| 969 | such as C<$ph-E<gt>{foo}[1]>, was accidentally disallowed. This has |
| 970 | been corrected. |
| 971 | |
| 972 | When applied to a pseudo-hash element, exists() now reports whether |
| 973 | the specified value exists, not merely if the key is valid. |
| 974 | |
| 975 | delete() now works on pseudo-hashes. When given a pseudo-hash element |
| 976 | or slice it deletes the values corresponding to the keys (but not the keys |
| 977 | themselves). See L<perlref/"Pseudo-hashes: Using an array as a hash">. |
| 978 | |
| 979 | =head2 C<goto &sub> and AUTOLOAD |
| 980 | |
| 981 | The C<goto &sub> construct works correctly when C<&sub> happens |
| 982 | to be autoloaded. |
| 983 | |
| 984 | =head2 C<-bareword> allowed under C<use integer> |
| 985 | |
| 986 | The autoquoting of barewords preceded by C<-> did not work |
| 987 | in prior versions when the C<integer> pragma was enabled. |
| 988 | This has been fixed. |
| 989 | |
| 990 | =head2 Boolean assignment operators are legal lvalues |
| 991 | |
| 992 | Constructs such as C<($a ||= 2) += 1> are now allowed. |
| 993 | |
| 994 | =head2 C<sort $coderef @foo> allowed |
| 995 | |
| 996 | sort() did not accept a subroutine reference as the comparison |
| 997 | function in earlier versions. This is now permitted. |
| 998 | |
| 999 | =head2 Failures in DESTROY() |
| 1000 | |
| 1001 | When code in a destructor threw an exception, it went unnoticed |
| 1002 | in earlier versions of Perl, unless someone happened to be |
| 1003 | looking in $@ just after the point the destructor happened to |
| 1004 | run. Such failures are now visible as warnings when warnings are |
| 1005 | enabled. |
| 1006 | |
| 1007 | =head2 Locale bugs fixed |
| 1008 | |
| 1009 | printf() and sprintf() previously reset the numeric locale |
| 1010 | back to the default "C" locale. This has been fixed. |
| 1011 | |
| 1012 | Numbers formatted according to the local numeric locale |
| 1013 | (such as using a decimal comma instead of a decimal dot) caused |
| 1014 | "isn't numeric" warnings, even while the operations accessing |
| 1015 | those numbers produced correct results. The warnings are gone. |
| 1016 | |
| 1017 | =head2 Memory leaks |
| 1018 | |
| 1019 | The C<eval 'return sub {...}'> construct could sometimes leak |
| 1020 | memory. This has been fixed. |
| 1021 | |
| 1022 | Operations that aren't filehandle constructors used to leak memory |
| 1023 | when used on invalid filehandles. This has been fixed. |
| 1024 | |
| 1025 | Constructs that modified C<@_> could fail to deallocate values |
| 1026 | in C<@_> and thus leak memory. This has been corrected. |
| 1027 | |
| 1028 | =head2 Spurious subroutine stubs after failed subroutine calls |
| 1029 | |
| 1030 | Perl could sometimes create empty subroutine stubs when a |
| 1031 | subroutine was not found in the package. Such cases stopped |
| 1032 | later method lookups from progressing into base packages. |
| 1033 | This has been corrected. |
| 1034 | |
| 1035 | =head2 Consistent numeric conversions |
| 1036 | |
| 1037 | change#3378,3318 |
| 1038 | [TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>] |
| 1039 | |
| 1040 | =head2 Taint failures under C<-U> |
| 1041 | |
| 1042 | When running in unsafe mode, taint violations could sometimes |
| 1043 | cause silent failures. This has been fixed. |
| 1044 | |
| 1045 | =head2 END blocks and the C<-c> switch |
| 1046 | |
| 1047 | Prior versions used to run BEGIN B<and> END blocks when Perl was |
| 1048 | run in compile-only mode. Since this is typically not the expected |
| 1049 | behavior, END blocks are not executed anymore when the C<-c> switch |
| 1050 | is used. |
| 1051 | |
| 1052 | See L<CHECK blocks> for how to run things when the compile phase ends. |
| 1053 | |
| 1054 | =head2 Potential to leak DATA filehandles |
| 1055 | |
| 1056 | Using the C<__DATA__> token creates an implicit filehandle to |
| 1057 | the file that contains the token. It is the program's |
| 1058 | responsibility to close it when it is done reading from it. |
| 1059 | |
| 1060 | This caveat is now better explained in the documentation. |
| 1061 | See L<perldata>. |
| 1062 | |
| 1063 | =head2 Diagnostics follow STDERR |
| 1064 | |
| 1065 | Diagnostic output now goes to whichever file the C<STDERR> handle |
| 1066 | is pointing at, instead of always going to the underlying C runtime |
| 1067 | library's C<stderr>. |
| 1068 | |
| 1069 | =head2 Other fixes for better diagnostics |
| 1070 | |
| 1071 | Line numbers are no longer suppressed (under most likely circumstances) |
| 1072 | during the global destruction phase. |
| 1073 | |
| 1074 | Diagnostics emitted from code running in threads other than the main |
| 1075 | thread are now accompanied by the thread ID. |
| 1076 | |
| 1077 | Embedded null characters in diagnostics now actually show up. They |
| 1078 | used to truncate the message in prior versions. |
| 1079 | |
| 1080 | $foo::a and $foo::b are now exempt from "possible typo" warnings only |
| 1081 | if sort() is encountered in package foo. |
| 1082 | |
| 1083 | Unrecognized alphabetic escapes encountered when parsing quote |
| 1084 | constructs now generate a warning, since they may take on new |
| 1085 | semantics in later versions of Perl. |
| 1086 | |
| 1087 | =head1 Performance enhancements |
| 1088 | |
| 1089 | =head2 Simple sort() using { $a <=> $b } and the like are optimized |
| 1090 | |
| 1091 | Many common sort() operations using a simple inlined block are now |
| 1092 | optimized for faster performance. |
| 1093 | |
| 1094 | =head2 Optimized assignments to lexical variables |
| 1095 | |
| 1096 | Certain operations in the RHS of assignment statements have been |
| 1097 | optimized to directly set the lexical variable on the LHS, |
| 1098 | eliminating redundant copying overheads. |
| 1099 | |
| 1100 | =head2 Method lookups optimized |
| 1101 | |
| 1102 | [TODO - Chip Salzenberg <chip@perlsupport.com>] |
| 1103 | |
| 1104 | =head2 Faster mechanism to invoke XSUBs |
| 1105 | |
| 1106 | change#4044,4125 |
| 1107 | [TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>] |
| 1108 | |
| 1109 | =head2 Perl_malloc() improvements |
| 1110 | |
| 1111 | change#4237 |
| 1112 | [TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>] |
| 1113 | |
| 1114 | =head2 Faster subroutine calls |
| 1115 | |
| 1116 | Minor changes in how subroutine calls are handled internally |
| 1117 | provide marginal improvements in performance. |
| 1118 | |
| 1119 | =head1 Platform specific changes |
| 1120 | |
| 1121 | =head2 Additional supported platforms |
| 1122 | |
| 1123 | =over 4 |
| 1124 | |
| 1125 | =item * |
| 1126 | |
| 1127 | VM/ESA is now supported. |
| 1128 | |
| 1129 | =item * |
| 1130 | |
| 1131 | Siemens BS2000 is now supported under the POSIX Shell. |
| 1132 | |
| 1133 | =item * |
| 1134 | |
| 1135 | The Mach CThreads (NEXTSTEP, OPENSTEP) are now supported by the Thread |
| 1136 | extension. |
| 1137 | |
| 1138 | =item * |
| 1139 | |
| 1140 | GNU/Hurd is now supported. |
| 1141 | |
| 1142 | =item * |
| 1143 | |
| 1144 | Rhapsody is now supported. |
| 1145 | |
| 1146 | =item * |
| 1147 | |
| 1148 | EPOC is is now supported (on Psion 5). |
| 1149 | |
| 1150 | =back |
| 1151 | |
| 1152 | =head2 DOS |
| 1153 | |
| 1154 | =over 4 |
| 1155 | |
| 1156 | =item * |
| 1157 | |
| 1158 | Perl now works with djgpp 2.02 (and 2.03 alpha). |
| 1159 | |
| 1160 | =item * |
| 1161 | |
| 1162 | Environment variable names are not converted to uppercase any more. |
| 1163 | |
| 1164 | =item * |
| 1165 | |
| 1166 | Wrong exit code from backticks now fixed. |
| 1167 | |
| 1168 | =item * |
| 1169 | |
| 1170 | This port is still using its own builtin globbing. |
| 1171 | |
| 1172 | =back |
| 1173 | |
| 1174 | =head2 OS/2 |
| 1175 | |
| 1176 | [TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>] |
| 1177 | |
| 1178 | =head2 VMS |
| 1179 | |
| 1180 | [TODO - Charles Bailey <bailey@newman.upenn.edu>] |
| 1181 | |
| 1182 | =head2 Win32 |
| 1183 | |
| 1184 | Site library searches failed to look for ".../site/5.XXX/lib" |
| 1185 | if ".../site/5.XXXYY/lib" wasn't found. This has been corrected. |
| 1186 | |
| 1187 | When given a pathname that consists only of a drivename, such |
| 1188 | as C<A:>, opendir() and stat() now use the current working |
| 1189 | directory for the drive rather than the drive root. |
| 1190 | |
| 1191 | The builtin XSUB functions in the Win32:: namespace are |
| 1192 | documented. See L<Win32>. |
| 1193 | |
| 1194 | $^X now contains the full path name of the running executable. |
| 1195 | |
| 1196 | A Win32::GetLongPathName() function is provided to complement |
| 1197 | Win32::GetFullPathName() and Win32::GetShortPathName(). See L<Win32>. |
| 1198 | |
| 1199 | POSIX::uname() is supported. |
| 1200 | |
| 1201 | system(1,...) now returns true process IDs rather than process |
| 1202 | handles. kill() accepts any real process id, rather than strictly |
| 1203 | return values from system(1,...). |
| 1204 | |
| 1205 | The C<Shell> module is supported. |
| 1206 | |
| 1207 | Rudimentary support for building under command.com in Windows 95 |
| 1208 | has been added. |
| 1209 | |
| 1210 | Scripts are read in binary mode by default to allow ByteLoader (and |
| 1211 | the filter mechanism in general) to work properly. For compatibility, |
| 1212 | the DATA filehandle will be set to text mode if a carriage return is |
| 1213 | detected at the end of the line containing the __END__ or __DATA__ |
| 1214 | token; if not, the DATA filehandle will be left open in binary mode. |
| 1215 | Earlier versions always opened the DATA filehandle in text mode. |
| 1216 | |
| 1217 | The glob() operator is implemented via the L<File::Glob> extension, |
| 1218 | which supports glob syntax of the C shell. This increases the flexibility |
| 1219 | of the glob() operator, but there may be compatibility issues for |
| 1220 | programs that relied on the older globbing syntax. If you want to |
| 1221 | preserve compatibility with the older syntax, you might want to put |
| 1222 | a C<use File::DosGlob;> in your program. For details and compatibility |
| 1223 | information, see L<File::Glob>. |
| 1224 | |
| 1225 | [TODO - GSAR] |
| 1226 | |
| 1227 | =head1 New tests |
| 1228 | |
| 1229 | =over 4 |
| 1230 | |
| 1231 | =item lib/attrs |
| 1232 | |
| 1233 | Compatibility tests for C<sub : attrs> vs the older C<use attrs>. |
| 1234 | |
| 1235 | =item lib/io_const |
| 1236 | |
| 1237 | IO constants (SEEK_*, _IO*). |
| 1238 | |
| 1239 | =item lib/io_dir |
| 1240 | |
| 1241 | Directory-related IO methods (new, read, close, rewind, tied delete). |
| 1242 | |
| 1243 | =item lib/io_multihomed |
| 1244 | |
| 1245 | INET sockets with multi-homed hosts. |
| 1246 | |
| 1247 | =item lib/io_poll |
| 1248 | |
| 1249 | IO poll(). |
| 1250 | |
| 1251 | =item lib/io_unix |
| 1252 | |
| 1253 | UNIX sockets. |
| 1254 | |
| 1255 | =item op/attrs |
| 1256 | |
| 1257 | Regression tests for C<my ($x,@y,%z) : attrs> and <sub : attrs>. |
| 1258 | |
| 1259 | =item op/filetest |
| 1260 | |
| 1261 | File test operators. |
| 1262 | |
| 1263 | =item op/lex_assign |
| 1264 | |
| 1265 | Verify operations that access pad objects (lexicals and temporaries). |
| 1266 | |
| 1267 | =item op/exists_sub |
| 1268 | |
| 1269 | Verify C<exists &sub> operations. |
| 1270 | |
| 1271 | =back |
| 1272 | |
| 1273 | =head1 Modules and Pragmata |
| 1274 | |
| 1275 | =head2 Modules |
| 1276 | |
| 1277 | =over 4 |
| 1278 | |
| 1279 | =item attributes |
| 1280 | |
| 1281 | While used internally by Perl as a pragma, this module also |
| 1282 | provides a way to fetch subroutine and variable attributes. |
| 1283 | See L<attributes>. |
| 1284 | |
| 1285 | =item B |
| 1286 | |
| 1287 | The Perl Compiler suite has been extensively reworked for this |
| 1288 | release. |
| 1289 | |
| 1290 | [TODO - Vishal Bhatia <vishal@gol.com>, |
| 1291 | Nick Ing-Simmons <nick@ni-s.u-net.com>] |
| 1292 | |
| 1293 | =item ByteLoader |
| 1294 | |
| 1295 | The ByteLoader is a dedicated extension to generate and run |
| 1296 | Perl bytecode. See L<ByteLoader>. |
| 1297 | |
| 1298 | =item constant |
| 1299 | |
| 1300 | References can now be used. |
| 1301 | |
| 1302 | The new version also allows a leading underscore in constant names, but |
| 1303 | disallows a double leading underscore (as in "__LINE__"). Some other names |
| 1304 | are disallowed or warned against, including BEGIN, END, etc. Some names |
| 1305 | which were forced into main:: used to fail silently in some cases; now they're |
| 1306 | fatal (outside of main::) and an optional warning (inside of main::). |
| 1307 | The ability to detect whether a constant had been set with a given name has |
| 1308 | been added. |
| 1309 | |
| 1310 | See L<constant>. |
| 1311 | |
| 1312 | =item charnames |
| 1313 | |
| 1314 | change#4052 |
| 1315 | [TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>] |
| 1316 | |
| 1317 | =item Data::Dumper |
| 1318 | |
| 1319 | A C<Maxdepth> setting can be specified to avoid venturing |
| 1320 | too deeply into deep data structures. See L<Data::Dumper>. |
| 1321 | |
| 1322 | Dumping C<qr//> objects works correctly. |
| 1323 | |
| 1324 | =item DB |
| 1325 | |
| 1326 | C<DB> is an experimental module that exposes a clean abstraction |
| 1327 | to Perl's debugging API. |
| 1328 | |
| 1329 | =item DB_File |
| 1330 | |
| 1331 | DB_File can now be built with Berkeley DB versions 1, 2 or 3. |
| 1332 | See C<ext/DB_File/Changes>. |
| 1333 | |
| 1334 | =item Devel::DProf |
| 1335 | |
| 1336 | Devel::DProf, a Perl source code profiler has been added. See |
| 1337 | L<Devel::DProf> and L<dprofpp>. |
| 1338 | |
| 1339 | =item Dumpvalue |
| 1340 | |
| 1341 | The Dumpvalue module provides screen dumps of Perl data. |
| 1342 | |
| 1343 | =item Benchmark |
| 1344 | |
| 1345 | Overall, Benchmark results exhibit lower average error and better timing |
| 1346 | accuracy. |
| 1347 | |
| 1348 | You can now run tests for I<n> seconds instead of guessing the right |
| 1349 | number of tests to run: e.g. timethese(-5, ...) will run each |
| 1350 | code for at least 5 CPU seconds. Zero as the "number of repetitions" |
| 1351 | means "for at least 3 CPU seconds". The output format has also |
| 1352 | changed. For example: |
| 1353 | |
| 1354 | use Benchmark;$x=3;timethese(-5,{a=>sub{$x*$x},b=>sub{$x**2}}) |
| 1355 | |
| 1356 | will now output something like this: |
| 1357 | |
| 1358 | Benchmark: running a, b, each for at least 5 CPU seconds... |
| 1359 | a: 5 wallclock secs ( 5.77 usr + 0.00 sys = 5.77 CPU) @ 200551.91/s (n=1156516) |
| 1360 | b: 4 wallclock secs ( 5.00 usr + 0.02 sys = 5.02 CPU) @ 159605.18/s (n=800686) |
| 1361 | |
| 1362 | New features: "each for at least N CPU seconds...", "wallclock secs", |
| 1363 | and the "@ operations/CPU second (n=operations)". |
| 1364 | |
| 1365 | timethese() now returns a reference to a hash of Benchmark objects containing |
| 1366 | the test results, keyed on the names of the tests. |
| 1367 | |
| 1368 | timethis() now returns the iterations field in the Benchmark result object |
| 1369 | instead of 0. |
| 1370 | |
| 1371 | timethese(), timethis(), and the new cmpthese() (see below) can also take |
| 1372 | a format specifier of 'none' to suppress output. |
| 1373 | |
| 1374 | A new function countit() is just like timeit() except that it takes a |
| 1375 | TIME instead of a COUNT. |
| 1376 | |
| 1377 | A new function cmpthese() prints a chart comparing the results of each test |
| 1378 | returned from a timethese() call. For each possible pair of tests, the |
| 1379 | percentage speed difference (iters/sec or seconds/iter) is shown. |
| 1380 | |
| 1381 | For other details, see L<Benchmark>. |
| 1382 | |
| 1383 | =item Devel::Peek |
| 1384 | |
| 1385 | The Devel::Peek module provides access to the internal representation |
| 1386 | of Perl variables and data. It is a data debugging tool for the XS programmer. |
| 1387 | |
| 1388 | =item ExtUtils::MakeMaker |
| 1389 | |
| 1390 | change#4135, also needs docs in module pod |
| 1391 | [TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>] |
| 1392 | |
| 1393 | =item Fcntl |
| 1394 | |
| 1395 | More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for |
| 1396 | large file (more than 4GB) access Note that the O_LARGEFILE is |
| 1397 | automatically/transparently added to sysopen() flags if large file |
| 1398 | support has been configured), Free/Net/OpenBSD locking behaviour flags |
| 1399 | F_FLOCK, F_POSIX, Linux F_SHLCK, and O_ACCMODE: the combined mask of |
| 1400 | O_RDONLY, O_WRONLY, and O_RDWR. The seek()/sysseek() constants |
| 1401 | SEEK_SET, SEEK_CUR, and SEEK_END are available via the C<:seek> tag. |
| 1402 | The chmod()/stat() S_IF* constants and S_IS* functions are available |
| 1403 | via the C<:mode> tag. |
| 1404 | |
| 1405 | |
| 1406 | =item File::Compare |
| 1407 | |
| 1408 | A compare_text() function has been added, which allows custom |
| 1409 | comparison functions. See L<File::Compare>. |
| 1410 | |
| 1411 | =item File::Find |
| 1412 | |
| 1413 | File::Find now works correctly when the wanted() function is either |
| 1414 | autoloaded or is a symbolic reference. |
| 1415 | |
| 1416 | A bug that caused File::Find to lose track of the working directory |
| 1417 | when pruning top-level directories has been fixed. |
| 1418 | |
| 1419 | File::Find now also supports several other options to control its |
| 1420 | behavior. It can follow symbolic links if the C<follow> option is |
| 1421 | specified. Enabling the C<no_chdir> option will make File::Find skip |
| 1422 | changing the current directory when walking directories. The C<untaint> |
| 1423 | flag can be useful when running with taint checks enabled. |
| 1424 | |
| 1425 | See L<File::Find>. |
| 1426 | |
| 1427 | =item File::Glob |
| 1428 | |
| 1429 | This extension implements BSD-style file globbing. By default, |
| 1430 | it will also be used for the internal implementation of the glob() |
| 1431 | operator. See L<File::Glob>. |
| 1432 | |
| 1433 | =item File::Spec |
| 1434 | |
| 1435 | New methods have been added to the File::Spec module: devnull() returns |
| 1436 | the name of the null device (/dev/null on Unix) and tmpdir() the name of |
| 1437 | the temp directory (normally /tmp on Unix). There are now also methods |
| 1438 | to convert between absolute and relative filenames: abs2rel() and |
| 1439 | rel2abs(). For compatibility with operating systems that specify volume |
| 1440 | names in file paths, the splitpath(), splitdir(), and catdir() methods |
| 1441 | have been added. |
| 1442 | |
| 1443 | =item File::Spec::Functions |
| 1444 | |
| 1445 | The new File::Spec::Functions modules provides a function interface |
| 1446 | to the File::Spec module. Allows shorthand |
| 1447 | |
| 1448 | $fullname = catfile($dir1, $dir2, $file); |
| 1449 | |
| 1450 | instead of |
| 1451 | |
| 1452 | $fullname = File::Spec->catfile($dir1, $dir2, $file); |
| 1453 | |
| 1454 | =item Getopt::Long |
| 1455 | |
| 1456 | Getopt::Long licensing has changed to allow the Perl Artistic License |
| 1457 | as well as the GPL. It used to be GPL only, which got in the way of |
| 1458 | non-GPL applications that wanted to use Getopt::Long. |
| 1459 | |
| 1460 | Getopt::Long encourages the use of Pod::Usage to produce help |
| 1461 | messages. For example: |
| 1462 | |
| 1463 | use Getopt::Long; |
| 1464 | use Pod::Usage; |
| 1465 | my $man = 0; |
| 1466 | my $help = 0; |
| 1467 | GetOptions('help|?' => \$help, man => \$man) or pod2usage(2); |
| 1468 | pod2usage(1) if $help; |
| 1469 | pod2usage(-exitstatus => 0, -verbose => 2) if $man; |
| 1470 | |
| 1471 | __END__ |
| 1472 | |
| 1473 | =head1 NAME |
| 1474 | |
| 1475 | sample - Using GetOpt::Long and Pod::Usage |
| 1476 | |
| 1477 | =head1 SYNOPSIS |
| 1478 | |
| 1479 | sample [options] [file ...] |
| 1480 | |
| 1481 | Options: |
| 1482 | -help brief help message |
| 1483 | -man full documentation |
| 1484 | |
| 1485 | =head1 OPTIONS |
| 1486 | |
| 1487 | =over 8 |
| 1488 | |
| 1489 | =item B<-help> |
| 1490 | |
| 1491 | Print a brief help message and exits. |
| 1492 | |
| 1493 | =item B<-man> |
| 1494 | |
| 1495 | Prints the manual page and exits. |
| 1496 | |
| 1497 | =back |
| 1498 | |
| 1499 | =head1 DESCRIPTION |
| 1500 | |
| 1501 | B<This program> will read the given input file(s) and do someting |
| 1502 | useful with the contents thereof. |
| 1503 | |
| 1504 | =cut |
| 1505 | |
| 1506 | See L<Pod::Usage> for details. |
| 1507 | |
| 1508 | A bug that prevented the non-option call-back E<lt>E<gt> from being |
| 1509 | specified as the first argument has been fixed. |
| 1510 | |
| 1511 | To specify the characters E<lt> and E<gt> as option starters, use |
| 1512 | E<gt>E<lt>. Note, however, that changing option starters is strongly |
| 1513 | deprecated. |
| 1514 | |
| 1515 | =item IO |
| 1516 | |
| 1517 | write() and syswrite() will now accept a single-argument |
| 1518 | form of the call, for consistency with Perl's syswrite(). |
| 1519 | |
| 1520 | You can now create a TCP-based IO::Socket::INET without forcing |
| 1521 | a connect attempt. This allows you to configure its options |
| 1522 | (like making it non-blocking) and then call connect() manually. |
| 1523 | |
| 1524 | A bug that prevented the IO::Socket::protocol() accessor |
| 1525 | from ever returning the correct value has been corrected. |
| 1526 | |
| 1527 | =item JPL |
| 1528 | |
| 1529 | Java Perl Lingo is now distributed with Perl. See jpl/README |
| 1530 | for more information. |
| 1531 | |
| 1532 | =item lib |
| 1533 | |
| 1534 | C<use lib> now weeds out any trailing duplicate entries. |
| 1535 | C<no lib> removes all named entries. |
| 1536 | |
| 1537 | =item Math::BigInt |
| 1538 | |
| 1539 | The bitwise operations C<E<lt>E<lt>>, C<E<gt>E<gt>>, C<&>, C<|>, |
| 1540 | and C<~> are now supported on bigints. |
| 1541 | |
| 1542 | =item Math::Complex |
| 1543 | |
| 1544 | The accessor methods Re, Im, arg, abs, rho, and theta can now also |
| 1545 | act as mutators (accessor $z->Re(), mutator $z->Re(3)). |
| 1546 | |
| 1547 | =item Math::Trig |
| 1548 | |
| 1549 | A little bit of radial trigonometry (cylindrical and spherical), |
| 1550 | radial coordinate conversions, and the great circle distance were added. |
| 1551 | |
| 1552 | =item Pod::Parser, Pod::InputObjects |
| 1553 | |
| 1554 | Pod::Parser is a base class for parsing and selecting sections of |
| 1555 | pod documentation from an input stream. This module takes care of |
| 1556 | identifying pod paragraphs and commands in the input and hands off the |
| 1557 | parsed paragraphs and commands to user-defined methods which are free |
| 1558 | to interpret or translate them as they see fit. |
| 1559 | |
| 1560 | Pod::InputObjects defines some input objects needed by Pod::Parser, and |
| 1561 | for advanced users of Pod::Parser that need more about a command besides |
| 1562 | its name and text. |
| 1563 | |
| 1564 | As of release 5.6 of Perl, Pod::Parser is now the officially sanctioned |
| 1565 | "base parser code" recommended for use by all pod2xxx translators. |
| 1566 | Pod::Text (pod2text) and Pod::Man (pod2man) have already been converted |
| 1567 | to use Pod::Parser and efforts to convert Pod::HTML (pod2html) are already |
| 1568 | underway. For any questions or comments about pod parsing and translating |
| 1569 | issues and utilities, please use the pod-people@perl.org mailing list. |
| 1570 | |
| 1571 | For further information, please see L<Pod::Parser> and L<Pod::InputObjects>. |
| 1572 | |
| 1573 | =item Pod::Checker, podchecker |
| 1574 | |
| 1575 | This utility checks pod files for correct syntax, according to |
| 1576 | L<perlpod>. Obvious errors are flagged as such, while warnings are |
| 1577 | printed for mistakes that can be handled gracefully. The checklist is |
| 1578 | not complete yet. See L<Pod::Checker>. |
| 1579 | |
| 1580 | =item Pod::ParseUtils, Pod::Find |
| 1581 | |
| 1582 | These modules provide a set of gizmos that are useful mainly for pod |
| 1583 | translators. L<Pod::Find|Pod::Find> traverses directory structures and |
| 1584 | returns found pod files, along with their canonical names (like |
| 1585 | C<File::Spec::Unix>). L<Pod::ParseUtils|Pod::ParseUtils> contains |
| 1586 | B<Pod::List> (useful for storing pod list information), B<Pod::Hyperlink> |
| 1587 | (for parsing the contents of C<LE<gt>E<lt>> sequences) and B<Pod::Cache> |
| 1588 | (for caching information about pod files, e.g. link nodes). |
| 1589 | |
| 1590 | =item Pod::Select, podselect |
| 1591 | |
| 1592 | Pod::Select is a subclass of Pod::Parser which provides a function |
| 1593 | named "podselect()" to filter out user-specified sections of raw pod |
| 1594 | documentation from an input stream. podselect is a script that provides |
| 1595 | access to Pod::Select from other scripts to be used as a filter. |
| 1596 | See L<Pod::Select>. |
| 1597 | |
| 1598 | =item Pod::Usage, pod2usage |
| 1599 | |
| 1600 | Pod::Usage provides the function "pod2usage()" to print usage messages for |
| 1601 | a Perl script based on its embedded pod documentation. The pod2usage() |
| 1602 | function is generally useful to all script authors since it lets them |
| 1603 | write and maintain a single source (the pods) for documentation, thus |
| 1604 | removing the need to create and maintain redundant usage message text |
| 1605 | consisting of information already in the pods. |
| 1606 | |
| 1607 | There is also a pod2usage script which can be used from other kinds of |
| 1608 | scripts to print usage messages from pods (even for non-Perl scripts |
| 1609 | with pods embedded in comments). |
| 1610 | |
| 1611 | For details and examples, please see L<Pod::Usage>. |
| 1612 | |
| 1613 | =item Pod::Text and Pod::Man |
| 1614 | |
| 1615 | [TODO - Russ Allbery <rra@stanford.edu>] |
| 1616 | |
| 1617 | =item SDBM_File |
| 1618 | |
| 1619 | An EXISTS method has been added to this module (and sdbm_exists() has |
| 1620 | been added to the underlying sdbm library), so one can now call exists |
| 1621 | on an SDBM_File tied hash and get the correct result, rather than a |
| 1622 | runtime error. |
| 1623 | |
| 1624 | A bug that may have caused data loss when more than one disk block |
| 1625 | happens to be read from the database in a single FETCH() has been |
| 1626 | fixed. |
| 1627 | |
| 1628 | =item Sys::Syslog |
| 1629 | |
| 1630 | Sys::Syslog now uses XSUBs to access facilities from syslog.h so it |
| 1631 | no longer requires syslog.ph to exist. |
| 1632 | |
| 1633 | =item Sys::Hostname |
| 1634 | |
| 1635 | Sys::Hostname now uses XSUBs to call the C library's gethostname() or |
| 1636 | uname() if they exist. |
| 1637 | |
| 1638 | =item Time::Local |
| 1639 | |
| 1640 | The timelocal() and timegm() functions used to silently return bogus |
| 1641 | results when the date fell outside the machine's integer range. They |
| 1642 | now consistently croak() if the date falls in an unsupported range. |
| 1643 | |
| 1644 | =item Win32 |
| 1645 | |
| 1646 | The error return value in list context has been changed for all functions |
| 1647 | that return a list of values. Previously these functions returned a list |
| 1648 | with a single element C<undef> if an error occurred. Now these functions |
| 1649 | return the empty list in these situations. This applies to the following |
| 1650 | functions: |
| 1651 | |
| 1652 | Win32::FsType |
| 1653 | Win32::GetOSVersion |
| 1654 | |
| 1655 | The remaining functions are unchanged and continue to return C<undef> on |
| 1656 | error even in list context. |
| 1657 | |
| 1658 | The Win32::SetLastError(ERROR) function has been added as a complement |
| 1659 | to the Win32::GetLastError() function. |
| 1660 | |
| 1661 | The new Win32::GetFullPathName(FILENAME) returns the full absolute |
| 1662 | pathname for FILENAME in scalar context. In list context it returns |
| 1663 | a two-element list containing the fully qualified directory name and |
| 1664 | the filename. See L<Win32>. |
| 1665 | |
| 1666 | =item DBM Filters |
| 1667 | |
| 1668 | A new feature called "DBM Filters" has been added to all the |
| 1669 | DBM modules--DB_File, GDBM_File, NDBM_File, ODBM_File, and SDBM_File. |
| 1670 | DBM Filters add four new methods to each DBM module: |
| 1671 | |
| 1672 | filter_store_key |
| 1673 | filter_store_value |
| 1674 | filter_fetch_key |
| 1675 | filter_fetch_value |
| 1676 | |
| 1677 | These can be used to filter key-value pairs before the pairs are |
| 1678 | written to the database or just after they are read from the database. |
| 1679 | See L<perldbmfilter> for further information. |
| 1680 | |
| 1681 | =back |
| 1682 | |
| 1683 | =head2 Pragmata |
| 1684 | |
| 1685 | C<use attrs> is now obsolete, and is only provided for |
| 1686 | backward-compatibility. It's been replaced by the C<sub : attributes> |
| 1687 | syntax. See L<perlsub/"Subroutine Attributes"> and L<attributes>. |
| 1688 | |
| 1689 | C<use utf8> to enable UTF-8 and Unicode support. |
| 1690 | |
| 1691 | Lexical warnings pragma, C<use warnings;>, to control optional warnings. |
| 1692 | See L<perllexwarn>. |
| 1693 | |
| 1694 | C<use filetest> to control the behaviour of filetests (C<-r> C<-w> |
| 1695 | ...). Currently only one subpragma implemented, "use filetest |
| 1696 | 'access';", that uses access(2) or equivalent to check permissions |
| 1697 | instead of using stat(2) as usual. This matters in filesystems |
| 1698 | where there are ACLs (access control lists): the stat(2) might lie, |
| 1699 | but access(2) knows better. |
| 1700 | |
| 1701 | =head1 Utility Changes |
| 1702 | |
| 1703 | =head2 h2ph |
| 1704 | |
| 1705 | [TODO - Kurt Starsinic <kstar@chapin.edu>] |
| 1706 | |
| 1707 | =head2 perlcc |
| 1708 | |
| 1709 | C<perlcc> now supports the C and Bytecode backends. By default, |
| 1710 | it generates output from the simple C backend rather than the |
| 1711 | optimized C backend. |
| 1712 | |
| 1713 | Support for non-Unix platforms has been improved. |
| 1714 | |
| 1715 | =head2 h2xs |
| 1716 | |
| 1717 | change#4232 |
| 1718 | [TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>] |
| 1719 | |
| 1720 | =head1 Documentation Changes |
| 1721 | |
| 1722 | =over 4 |
| 1723 | |
| 1724 | =item perlapi.pod |
| 1725 | |
| 1726 | The official list of public Perl API functions. |
| 1727 | |
| 1728 | =item perlcompile.pod |
| 1729 | |
| 1730 | An introduction to using the Perl Compiler suite. |
| 1731 | |
| 1732 | =item perlfilter.pod |
| 1733 | |
| 1734 | An introduction to writing Perl source filters. |
| 1735 | |
| 1736 | =item perlhack.pod |
| 1737 | |
| 1738 | Some guidelines for hacking the Perl source code. |
| 1739 | |
| 1740 | =item perlintern.pod |
| 1741 | |
| 1742 | A list of internal functions in the Perl source code. |
| 1743 | (List is currently empty.) |
| 1744 | |
| 1745 | =item perlopentut.pod |
| 1746 | |
| 1747 | A tutorial on using open() effectively. |
| 1748 | |
| 1749 | =item perlreftut.pod |
| 1750 | |
| 1751 | A tutorial that introduces the essentials of references. |
| 1752 | |
| 1753 | =item perltootc.pod |
| 1754 | |
| 1755 | A tutorial on managing class data for object modules. |
| 1756 | |
| 1757 | =item perlunicode.pod |
| 1758 | |
| 1759 | An introduction to Unicode support features in Perl. |
| 1760 | |
| 1761 | =back |
| 1762 | |
| 1763 | =head1 New or Changed Diagnostics |
| 1764 | |
| 1765 | =over 4 |
| 1766 | |
| 1767 | =item "%s" variable %s masks earlier declaration in same %s |
| 1768 | |
| 1769 | (W) A "my" or "our" variable has been redeclared in the current scope or statement, |
| 1770 | effectively eliminating all access to the previous instance. This is almost |
| 1771 | always a typographical error. Note that the earlier variable will still exist |
| 1772 | until the end of the scope or until all closure referents to it are |
| 1773 | destroyed. |
| 1774 | |
| 1775 | =item "my sub" not yet implemented |
| 1776 | |
| 1777 | (F) Lexically scoped subroutines are not yet implemented. Don't try that |
| 1778 | yet. |
| 1779 | |
| 1780 | =item "our" variable %s redeclared |
| 1781 | |
| 1782 | (W) You seem to have already declared the same global once before in the |
| 1783 | current lexical scope. |
| 1784 | |
| 1785 | =item '!' allowed only after types %s |
| 1786 | |
| 1787 | (F) The '!' is allowed in pack() and unpack() only after certain types. |
| 1788 | See L<perlfunc/pack>. |
| 1789 | |
| 1790 | =item / cannot take a count |
| 1791 | |
| 1792 | (F) You had an unpack template indicating a counted-length string, |
| 1793 | but you have also specified an explicit size for the string. |
| 1794 | See L<perlfunc/pack>. |
| 1795 | |
| 1796 | =item / must be followed by a, A or Z |
| 1797 | |
| 1798 | (F) You had an unpack template indicating a counted-length string, |
| 1799 | which must be followed by one of the letters a, A or Z |
| 1800 | to indicate what sort of string is to be unpacked. |
| 1801 | See L<perlfunc/pack>. |
| 1802 | |
| 1803 | =item / must be followed by a*, A* or Z* |
| 1804 | |
| 1805 | (F) You had a pack template indicating a counted-length string, |
| 1806 | Currently the only things that can have their length counted are a*, A* or Z*. |
| 1807 | See L<perlfunc/pack>. |
| 1808 | |
| 1809 | =item / must follow a numeric type |
| 1810 | |
| 1811 | (F) You had an unpack template that contained a '#', |
| 1812 | but this did not follow some numeric unpack specification. |
| 1813 | See L<perlfunc/pack>. |
| 1814 | |
| 1815 | =item /%s/: Unrecognized escape \\%c passed through |
| 1816 | |
| 1817 | (W) You used a backslash-character combination which is not recognized |
| 1818 | by Perl. This combination appears in an interpolated variable or a |
| 1819 | C<'>-delimited regular expression. The character was understood literally. |
| 1820 | |
| 1821 | =item /%s/: Unrecognized escape \\%c in character class passed through |
| 1822 | |
| 1823 | (W) You used a backslash-character combination which is not recognized |
| 1824 | by Perl inside character classes. The character was understood literally. |
| 1825 | |
| 1826 | =item /%s/ should probably be written as "%s" |
| 1827 | |
| 1828 | (W) You have used a pattern where Perl expected to find a string, |
| 1829 | as in the first argument to C<join>. Perl will treat the true |
| 1830 | or false result of matching the pattern against $_ as the string, |
| 1831 | which is probably not what you had in mind. |
| 1832 | |
| 1833 | =item %s() called too early to check prototype |
| 1834 | |
| 1835 | (W) You've called a function that has a prototype before the parser saw a |
| 1836 | definition or declaration for it, and Perl could not check that the call |
| 1837 | conforms to the prototype. You need to either add an early prototype |
| 1838 | declaration for the subroutine in question, or move the subroutine |
| 1839 | definition ahead of the call to get proper prototype checking. Alternatively, |
| 1840 | if you are certain that you're calling the function correctly, you may put |
| 1841 | an ampersand before the name to avoid the warning. See L<perlsub>. |
| 1842 | |
| 1843 | =item %s argument is not a HASH or ARRAY element |
| 1844 | |
| 1845 | (F) The argument to exists() must be a hash or array element, such as: |
| 1846 | |
| 1847 | $foo{$bar} |
| 1848 | $ref->[12]->["susie"] |
| 1849 | |
| 1850 | =item %s argument is not a HASH or ARRAY element or slice |
| 1851 | |
| 1852 | (F) The argument to delete() must be either a hash or array element, such as: |
| 1853 | |
| 1854 | $foo{$bar} |
| 1855 | $ref->[12]->["susie"] |
| 1856 | |
| 1857 | or a hash or array slice, such as: |
| 1858 | |
| 1859 | @foo[$bar, $baz, $xyzzy] |
| 1860 | @{$ref->[12]}{"susie", "queue"} |
| 1861 | |
| 1862 | =item %s argument is not a subroutine name |
| 1863 | |
| 1864 | (F) The argument to exists() for C<exists &sub> must be a subroutine |
| 1865 | name, and not a subroutine call. C<exists &sub()> will generate this error. |
| 1866 | |
| 1867 | =item %s package attribute may clash with future reserved word: %s |
| 1868 | |
| 1869 | (W) A lowercase attribute name was used that had a package-specific handler. |
| 1870 | That name might have a meaning to Perl itself some day, even though it |
| 1871 | doesn't yet. Perhaps you should use a mixed-case attribute name, instead. |
| 1872 | See L<attributes>. |
| 1873 | |
| 1874 | =item (in cleanup) %s |
| 1875 | |
| 1876 | (W) This prefix usually indicates that a DESTROY() method raised |
| 1877 | the indicated exception. Since destructors are usually called by |
| 1878 | the system at arbitrary points during execution, and often a vast |
| 1879 | number of times, the warning is issued only once for any number |
| 1880 | of failures that would otherwise result in the same message being |
| 1881 | repeated. |
| 1882 | |
| 1883 | Failure of user callbacks dispatched using the C<G_KEEPERR> flag |
| 1884 | could also result in this warning. See L<perlcall/G_KEEPERR>. |
| 1885 | |
| 1886 | =item <> should be quotes |
| 1887 | |
| 1888 | (F) You wrote C<require E<lt>fileE<gt>> when you should have written |
| 1889 | C<require 'file'>. |
| 1890 | |
| 1891 | =item Attempt to join self |
| 1892 | |
| 1893 | (F) You tried to join a thread from within itself, which is an |
| 1894 | impossible task. You may be joining the wrong thread, or you may |
| 1895 | need to move the join() to some other thread. |
| 1896 | |
| 1897 | =item Bad evalled substitution pattern |
| 1898 | |
| 1899 | (F) You've used the /e switch to evaluate the replacement for a |
| 1900 | substitution, but perl found a syntax error in the code to evaluate, |
| 1901 | most likely an unexpected right brace '}'. |
| 1902 | |
| 1903 | =item Bad realloc() ignored |
| 1904 | |
| 1905 | (S) An internal routine called realloc() on something that had never been |
| 1906 | malloc()ed in the first place. Mandatory, but can be disabled by |
| 1907 | setting environment variable C<PERL_BADFREE> to 1. |
| 1908 | |
| 1909 | =item Binary number > 0b11111111111111111111111111111111 non-portable |
| 1910 | |
| 1911 | (W) The binary number you specified is larger than 2**32-1 |
| 1912 | (4294967295) and therefore non-portable between systems. See |
| 1913 | L<perlport> for more on portability concerns. |
| 1914 | |
| 1915 | =item Bit vector size > 32 non-portable |
| 1916 | |
| 1917 | (W) Using bit vector sizes larger than 32 is non-portable. |
| 1918 | |
| 1919 | =item Buffer overflow in prime_env_iter: %s |
| 1920 | |
| 1921 | (W) A warning peculiar to VMS. While Perl was preparing to iterate over |
| 1922 | %ENV, it encountered a logical name or symbol definition which was too long, |
| 1923 | so it was truncated to the string shown. |
| 1924 | |
| 1925 | =item Can't check filesystem of script "%s" |
| 1926 | |
| 1927 | (P) For some reason you can't check the filesystem of the script for nosuid. |
| 1928 | |
| 1929 | =item Can't declare class for non-scalar %s in "%s" |
| 1930 | |
| 1931 | (S) Currently, only scalar variables can declared with a specific class |
| 1932 | qualifier in a "my" or "our" declaration. The semantics may be extended |
| 1933 | for other types of variables in future. |
| 1934 | |
| 1935 | =item Can't declare %s in "%s" |
| 1936 | |
| 1937 | (F) Only scalar, array, and hash variables may be declared as "my" or |
| 1938 | "our" variables. They must have ordinary identifiers as names. |
| 1939 | |
| 1940 | =item Can't ignore signal CHLD, forcing to default |
| 1941 | |
| 1942 | (W) Perl has detected that it is being run with the SIGCHLD signal |
| 1943 | (sometimes known as SIGCLD) disabled. Since disabling this signal |
| 1944 | will interfere with proper determination of exit status of child |
| 1945 | processes, Perl has reset the signal to its default value. |
| 1946 | This situation typically indicates that the parent program under |
| 1947 | which Perl may be running (e.g. cron) is being very careless. |
| 1948 | |
| 1949 | =item Can't modify non-lvalue subroutine call |
| 1950 | |
| 1951 | (F) Subroutines meant to be used in lvalue context should be declared as |
| 1952 | such, see L<perlsub/"Lvalue subroutines">. |
| 1953 | |
| 1954 | =item Can't read CRTL environ |
| 1955 | |
| 1956 | (S) A warning peculiar to VMS. Perl tried to read an element of %ENV |
| 1957 | from the CRTL's internal environment array and discovered the array was |
| 1958 | missing. You need to figure out where your CRTL misplaced its environ |
| 1959 | or define F<PERL_ENV_TABLES> (see L<perlvms>) so that environ is not searched. |
| 1960 | |
| 1961 | =item Can't remove %s: %s, skipping file |
| 1962 | |
| 1963 | (S) You requested an inplace edit without creating a backup file. Perl |
| 1964 | was unable to remove the original file to replace it with the modified |
| 1965 | file. The file was left unmodified. |
| 1966 | |
| 1967 | =item Can't return %s from lvalue subroutine |
| 1968 | |
| 1969 | (F) Perl detected an attempt to return illegal lvalues (such |
| 1970 | as temporary or readonly values) from a subroutine used as an lvalue. |
| 1971 | This is not allowed. |
| 1972 | |
| 1973 | =item Can't weaken a nonreference |
| 1974 | |
| 1975 | (F) You attempted to weaken something that was not a reference. Only |
| 1976 | references can be weakened. |
| 1977 | |
| 1978 | =item Character class [:%s:] unknown |
| 1979 | |
| 1980 | (F) The class in the character class [: :] syntax is unknown. |
| 1981 | See L<perlre>. |
| 1982 | |
| 1983 | =item Character class syntax [%s] belongs inside character classes |
| 1984 | |
| 1985 | (W) The character class constructs [: :], [= =], and [. .] go |
| 1986 | I<inside> character classes, the [] are part of the construct, |
| 1987 | for example: /[012[:alpha:]345]/. Note that [= =] and [. .] |
| 1988 | are not currently implemented; they are simply placeholders for |
| 1989 | future extensions. |
| 1990 | |
| 1991 | =item Constant is not %s reference |
| 1992 | |
| 1993 | (F) A constant value (perhaps declared using the C<use constant> pragma) |
| 1994 | is being dereferenced, but it amounts to the wrong type of reference. The |
| 1995 | message indicates the type of reference that was expected. This usually |
| 1996 | indicates a syntax error in dereferencing the constant value. |
| 1997 | See L<perlsub/"Constant Functions"> and L<constant>. |
| 1998 | |
| 1999 | =item constant(%s): %%^H is not localized |
| 2000 | |
| 2001 | (F) When setting compile-time-lexicalized hash %^H one should set the |
| 2002 | corresponding bit of $^H as well. |
| 2003 | |
| 2004 | =item constant(%s): %s |
| 2005 | |
| 2006 | (F) Compile-time-substitutions (such as overloaded constants and |
| 2007 | character names) were not correctly set up. |
| 2008 | |
| 2009 | =item defined(@array) is deprecated |
| 2010 | |
| 2011 | (D) defined() is not usually useful on arrays because it checks for an |
| 2012 | undefined I<scalar> value. If you want to see if the array is empty, |
| 2013 | just use C<if (@array) { # not empty }> for example. |
| 2014 | |
| 2015 | =item defined(%hash) is deprecated |
| 2016 | |
| 2017 | (D) defined() is not usually useful on hashes because it checks for an |
| 2018 | undefined I<scalar> value. If you want to see if the hash is empty, |
| 2019 | just use C<if (%hash) { # not empty }> for example. |
| 2020 | |
| 2021 | =item Did not produce a valid header |
| 2022 | |
| 2023 | See Server error. |
| 2024 | |
| 2025 | =item Did you mean "local" instead of "our"? |
| 2026 | |
| 2027 | (W) Remember that "our" does not localize the declared global variable. |
| 2028 | You have declared it again in the same lexical scope, which seems superfluous. |
| 2029 | |
| 2030 | =item Document contains no data |
| 2031 | |
| 2032 | See Server error. |
| 2033 | |
| 2034 | =item entering effective %s failed |
| 2035 | |
| 2036 | (F) While under the C<use filetest> pragma, switching the real and |
| 2037 | effective uids or gids failed. |
| 2038 | |
| 2039 | =item false [] range "%s" in regexp |
| 2040 | |
| 2041 | (W) A character class range must start and end at a literal character, not |
| 2042 | another character class like C<\d> or C<[:alpha:]>. The "-" in your false |
| 2043 | range is interpreted as a literal "-". Consider quoting the "-", "\-". |
| 2044 | See L<perlre>. |
| 2045 | |
| 2046 | =item Filehandle %s opened only for output |
| 2047 | |
| 2048 | (W) You tried to read from a filehandle opened only for writing. If you |
| 2049 | intended it to be a read/write filehandle, you needed to open it with |
| 2050 | "+E<lt>" or "+E<gt>" or "+E<gt>E<gt>" instead of with "E<lt>" or nothing. If |
| 2051 | you intended only to read from the file, use "E<lt>". See |
| 2052 | L<perlfunc/open>. |
| 2053 | |
| 2054 | =item flock() on closed filehandle %s |
| 2055 | |
| 2056 | (W) The filehandle you're attempting to flock() got itself closed some |
| 2057 | time before now. Check your logic flow. flock() operates on filehandles. |
| 2058 | Are you attempting to call flock() on a dirhandle by the same name? |
| 2059 | |
| 2060 | =item Global symbol "%s" requires explicit package name |
| 2061 | |
| 2062 | (F) You've said "use strict vars", which indicates that all variables |
| 2063 | must either be lexically scoped (using "my"), declared beforehand using |
| 2064 | "our", or explicitly qualified to say which package the global variable |
| 2065 | is in (using "::"). |
| 2066 | |
| 2067 | =item Hexadecimal number > 0xffffffff non-portable |
| 2068 | |
| 2069 | (W) The hexadecimal number you specified is larger than 2**32-1 |
| 2070 | (4294967295) and therefore non-portable between systems. See |
| 2071 | L<perlport> for more on portability concerns. |
| 2072 | |
| 2073 | =item Ill-formed CRTL environ value "%s" |
| 2074 | |
| 2075 | (W) A warning peculiar to VMS. Perl tried to read the CRTL's internal |
| 2076 | environ array, and encountered an element without the C<=> delimiter |
| 2077 | used to spearate keys from values. The element is ignored. |
| 2078 | |
| 2079 | =item Ill-formed message in prime_env_iter: |%s| |
| 2080 | |
| 2081 | (W) A warning peculiar to VMS. Perl tried to read a logical name |
| 2082 | or CLI symbol definition when preparing to iterate over %ENV, and |
| 2083 | didn't see the expected delimiter between key and value, so the |
| 2084 | line was ignored. |
| 2085 | |
| 2086 | =item Illegal binary digit %s |
| 2087 | |
| 2088 | (F) You used a digit other than 0 or 1 in a binary number. |
| 2089 | |
| 2090 | =item Illegal binary digit %s ignored |
| 2091 | |
| 2092 | (W) You may have tried to use a digit other than 0 or 1 in a binary number. |
| 2093 | Interpretation of the binary number stopped before the offending digit. |
| 2094 | |
| 2095 | =item Illegal number of bits in vec |
| 2096 | |
| 2097 | (F) The number of bits in vec() (the third argument) must be a power of |
| 2098 | two from 1 to 32 (or 64, if your platform supports that). |
| 2099 | |
| 2100 | =item Integer overflow in %s number |
| 2101 | |
| 2102 | (W) The hexadecimal, octal or binary number you have specified either |
| 2103 | as a literal or as an argument to hex() or oct() is too big for your |
| 2104 | architecture, and has been converted to a floating point number. On a |
| 2105 | 32-bit architecture the largest hexadecimal, octal or binary number |
| 2106 | representable without overflow is 0xFFFFFFFF, 037777777777, or |
| 2107 | 0b11111111111111111111111111111111 respectively. Note that Perl |
| 2108 | transparently promotes all numbers to a floating point representation |
| 2109 | internally--subject to loss of precision errors in subsequent |
| 2110 | operations. |
| 2111 | |
| 2112 | =item Invalid %s attribute: %s |
| 2113 | |
| 2114 | The indicated attribute for a subroutine or variable was not recognized |
| 2115 | by Perl or by a user-supplied handler. See L<attributes>. |
| 2116 | |
| 2117 | =item Invalid %s attributes: %s |
| 2118 | |
| 2119 | The indicated attributes for a subroutine or variable were not recognized |
| 2120 | by Perl or by a user-supplied handler. See L<attributes>. |
| 2121 | |
| 2122 | =item invalid [] range "%s" in regexp |
| 2123 | |
| 2124 | The offending range is now explicitly displayed. |
| 2125 | |
| 2126 | =item Invalid separator character %s in attribute list |
| 2127 | |
| 2128 | (F) Something other than a colon or whitespace was seen between the |
| 2129 | elements of an attribute list. If the previous attribute |
| 2130 | had a parenthesised parameter list, perhaps that list was terminated |
| 2131 | too soon. See L<attributes>. |
| 2132 | |
| 2133 | =item Invalid separator character %s in subroutine attribute list |
| 2134 | |
| 2135 | (F) Something other than a colon or whitespace was seen between the |
| 2136 | elements of a subroutine attribute list. If the previous attribute |
| 2137 | had a parenthesised parameter list, perhaps that list was terminated |
| 2138 | too soon. |
| 2139 | |
| 2140 | =item leaving effective %s failed |
| 2141 | |
| 2142 | (F) While under the C<use filetest> pragma, switching the real and |
| 2143 | effective uids or gids failed. |
| 2144 | |
| 2145 | =item Lvalue subs returning %s not implemented yet |
| 2146 | |
| 2147 | (F) Due to limitations in the current implementation, array and hash |
| 2148 | values cannot be returned in subroutines used in lvalue context. |
| 2149 | See L<perlsub/"Lvalue subroutines">. |
| 2150 | |
| 2151 | =item Method %s not permitted |
| 2152 | |
| 2153 | See Server error. |
| 2154 | |
| 2155 | =item Missing %sbrace%s on \N{} |
| 2156 | |
| 2157 | (F) Wrong syntax of character name literal C<\N{charname}> within |
| 2158 | double-quotish context. |
| 2159 | |
| 2160 | =item Missing command in piped open |
| 2161 | |
| 2162 | (W) You used the C<open(FH, "| command")> or C<open(FH, "command |")> |
| 2163 | construction, but the command was missing or blank. |
| 2164 | |
| 2165 | =item Missing name in "my sub" |
| 2166 | |
| 2167 | (F) The reserved syntax for lexically scoped subroutines requires that they |
| 2168 | have a name with which they can be found. |
| 2169 | |
| 2170 | =item No %s specified for -%c |
| 2171 | |
| 2172 | (F) The indicated command line switch needs a mandatory argument, but |
| 2173 | you haven't specified one. |
| 2174 | |
| 2175 | =item No package name allowed for variable %s in "our" |
| 2176 | |
| 2177 | (F) Fully qualified variable names are not allowed in "our" declarations, |
| 2178 | because that doesn't make much sense under existing semantics. Such |
| 2179 | syntax is reserved for future extensions. |
| 2180 | |
| 2181 | =item No space allowed after -%c |
| 2182 | |
| 2183 | (F) The argument to the indicated command line switch must follow immediately |
| 2184 | after the switch, without intervening spaces. |
| 2185 | |
| 2186 | =item no UTC offset information; assuming local time is UTC |
| 2187 | |
| 2188 | (S) A warning peculiar to VMS. Perl was unable to find the local |
| 2189 | timezone offset, so it's assuming that local system time is equivalent |
| 2190 | to UTC. If it's not, define the logical name F<SYS$TIMEZONE_DIFFERENTIAL> |
| 2191 | to translate to the number of seconds which need to be added to UTC to |
| 2192 | get local time. |
| 2193 | |
| 2194 | =item Octal number > 037777777777 non-portable |
| 2195 | |
| 2196 | (W) The octal number you specified is larger than 2**32-1 (4294967295) |
| 2197 | and therefore non-portable between systems. See L<perlport> for more |
| 2198 | on portability concerns. |
| 2199 | |
| 2200 | See also L<perlport> for writing portable code. |
| 2201 | |
| 2202 | =item panic: del_backref |
| 2203 | |
| 2204 | (P) Failed an internal consistency check while trying to reset a weak |
| 2205 | reference. |
| 2206 | |
| 2207 | =item panic: kid popen errno read |
| 2208 | |
| 2209 | (F) forked child returned an incomprehensible message about its errno. |
| 2210 | |
| 2211 | =item panic: magic_killbackrefs |
| 2212 | |
| 2213 | (P) Failed an internal consistency check while trying to reset all weak |
| 2214 | references to an object. |
| 2215 | |
| 2216 | =item Parentheses missing around "%s" list |
| 2217 | |
| 2218 | (W) You said something like |
| 2219 | |
| 2220 | my $foo, $bar = @_; |
| 2221 | |
| 2222 | when you meant |
| 2223 | |
| 2224 | my ($foo, $bar) = @_; |
| 2225 | |
| 2226 | Remember that "my", "our" and "local" bind closer than comma. |
| 2227 | |
| 2228 | =item Possible Y2K bug: %s |
| 2229 | |
| 2230 | (W) You are concatenating the number 19 with another number, which |
| 2231 | could be a potential Year 2000 problem. |
| 2232 | |
| 2233 | =item Premature end of script headers |
| 2234 | |
| 2235 | See Server error. |
| 2236 | |
| 2237 | =item Repeat count in pack overflows |
| 2238 | |
| 2239 | (F) You can't specify a repeat count so large that it overflows |
| 2240 | your signed integers. See L<perlfunc/pack>. |
| 2241 | |
| 2242 | =item Repeat count in unpack overflows |
| 2243 | |
| 2244 | (F) You can't specify a repeat count so large that it overflows |
| 2245 | your signed integers. See L<perlfunc/unpack>. |
| 2246 | |
| 2247 | =item realloc() of freed memory ignored |
| 2248 | |
| 2249 | (S) An internal routine called realloc() on something that had already |
| 2250 | been freed. |
| 2251 | |
| 2252 | =item Reference is already weak |
| 2253 | |
| 2254 | (W) You have attempted to weaken a reference that is already weak. |
| 2255 | Doing so has no effect. |
| 2256 | |
| 2257 | =item setpgrp can't take arguments |
| 2258 | |
| 2259 | (F) Your system has the setpgrp() from BSD 4.2, which takes no arguments, |
| 2260 | unlike POSIX setpgid(), which takes a process ID and process group ID. |
| 2261 | |
| 2262 | =item Strange *+?{} on zero-length expression |
| 2263 | |
| 2264 | (W) You applied a regular expression quantifier in a place where it |
| 2265 | makes no sense, such as on a zero-width assertion. |
| 2266 | Try putting the quantifier inside the assertion instead. For example, |
| 2267 | the way to match "abc" provided that it is followed by three |
| 2268 | repetitions of "xyz" is C</abc(?=(?:xyz){3})/>, not C</abc(?=xyz){3}/>. |
| 2269 | |
| 2270 | =item switching effective %s is not implemented |
| 2271 | |
| 2272 | (F) While under the C<use filetest> pragma, we cannot switch the |
| 2273 | real and effective uids or gids. |
| 2274 | |
| 2275 | =item This Perl can't reset CRTL environ elements (%s) |
| 2276 | |
| 2277 | =item This Perl can't set CRTL environ elements (%s=%s) |
| 2278 | |
| 2279 | (W) Warnings peculiar to VMS. You tried to change or delete an element |
| 2280 | of the CRTL's internal environ array, but your copy of Perl wasn't |
| 2281 | built with a CRTL that contained the setenv() function. You'll need to |
| 2282 | rebuild Perl with a CRTL that does, or redefine F<PERL_ENV_TABLES> (see |
| 2283 | L<perlvms>) so that the environ array isn't the target of the change to |
| 2284 | %ENV which produced the warning. |
| 2285 | |
| 2286 | =item Unknown open() mode '%s' |
| 2287 | |
| 2288 | (F) The second argument of 3-argument open() is not among the list |
| 2289 | of valid modes: C<E<lt>>, C<E<gt>>, C<E<gt>E<gt>>, C<+E<lt>>, |
| 2290 | C<+E<gt>>, C<+E<gt>E<gt>>, C<-|>, C<|E<45>>. |
| 2291 | |
| 2292 | =item Unknown process %x sent message to prime_env_iter: %s |
| 2293 | |
| 2294 | (P) An error peculiar to VMS. Perl was reading values for %ENV before |
| 2295 | iterating over it, and someone else stuck a message in the stream of |
| 2296 | data Perl expected. Someone's very confused, or perhaps trying to |
| 2297 | subvert Perl's population of %ENV for nefarious purposes. |
| 2298 | |
| 2299 | =item Unrecognized escape \\%c passed through |
| 2300 | |
| 2301 | (W) You used a backslash-character combination which is not recognized |
| 2302 | by Perl. The character was understood literally. |
| 2303 | |
| 2304 | =item Unterminated attribute parameter in attribute list |
| 2305 | |
| 2306 | (F) The lexer saw an opening (left) parenthesis character while parsing an |
| 2307 | attribute list, but the matching closing (right) parenthesis |
| 2308 | character was not found. You may need to add (or remove) a backslash |
| 2309 | character to get your parentheses to balance. See L<attributes>. |
| 2310 | |
| 2311 | =item Unterminated attribute list |
| 2312 | |
| 2313 | (F) The lexer found something other than a simple identifier at the start |
| 2314 | of an attribute, and it wasn't a semicolon or the start of a |
| 2315 | block. Perhaps you terminated the parameter list of the previous attribute |
| 2316 | too soon. See L<attributes>. |
| 2317 | |
| 2318 | =item Unterminated attribute parameter in subroutine attribute list |
| 2319 | |
| 2320 | (F) The lexer saw an opening (left) parenthesis character while parsing a |
| 2321 | subroutine attribute list, but the matching closing (right) parenthesis |
| 2322 | character was not found. You may need to add (or remove) a backslash |
| 2323 | character to get your parentheses to balance. |
| 2324 | |
| 2325 | =item Unterminated subroutine attribute list |
| 2326 | |
| 2327 | (F) The lexer found something other than a simple identifier at the start |
| 2328 | of a subroutine attribute, and it wasn't a semicolon or the start of a |
| 2329 | block. Perhaps you terminated the parameter list of the previous attribute |
| 2330 | too soon. |
| 2331 | |
| 2332 | =item Value of CLI symbol "%s" too long |
| 2333 | |
| 2334 | (W) A warning peculiar to VMS. Perl tried to read the value of an %ENV |
| 2335 | element from a CLI symbol table, and found a resultant string longer |
| 2336 | than 1024 characters. The return value has been truncated to 1024 |
| 2337 | characters. |
| 2338 | |
| 2339 | =item Version number must be a constant number |
| 2340 | |
| 2341 | (P) The attempt to translate a C<use Module n.n LIST> statement into |
| 2342 | its equivalent C<BEGIN> block found an internal inconsistency with |
| 2343 | the version number. |
| 2344 | |
| 2345 | =back |
| 2346 | |
| 2347 | =head1 Obsolete Diagnostics |
| 2348 | |
| 2349 | =over 4 |
| 2350 | |
| 2351 | =item Character class syntax [: :] is reserved for future extensions |
| 2352 | |
| 2353 | (W) Within regular expression character classes ([]) the syntax beginning |
| 2354 | with "[:" and ending with ":]" is reserved for future extensions. |
| 2355 | If you need to represent those character sequences inside a regular |
| 2356 | expression character class, just quote the square brackets with the |
| 2357 | backslash: "\[:" and ":\]". |
| 2358 | |
| 2359 | =item Ill-formed logical name |%s| in prime_env_iter |
| 2360 | |
| 2361 | (W) A warning peculiar to VMS. A logical name was encountered when preparing |
| 2362 | to iterate over %ENV which violates the syntactic rules governing logical |
| 2363 | names. Because it cannot be translated normally, it is skipped, and will not |
| 2364 | appear in %ENV. This may be a benign occurrence, as some software packages |
| 2365 | might directly modify logical name tables and introduce nonstandard names, |
| 2366 | or it may indicate that a logical name table has been corrupted. |
| 2367 | |
| 2368 | =item regexp too big |
| 2369 | |
| 2370 | (F) The current implementation of regular expressions uses shorts as |
| 2371 | address offsets within a string. Unfortunately this means that if |
| 2372 | the regular expression compiles to longer than 32767, it'll blow up. |
| 2373 | Usually when you want a regular expression this big, there is a better |
| 2374 | way to do it with multiple statements. See L<perlre>. |
| 2375 | |
| 2376 | =item Use of "$$<digit>" to mean "${$}<digit>" is deprecated |
| 2377 | |
| 2378 | (D) Perl versions before 5.004 misinterpreted any type marker followed |
| 2379 | by "$" and a digit. For example, "$$0" was incorrectly taken to mean |
| 2380 | "${$}0" instead of "${$0}". This bug is (mostly) fixed in Perl 5.004. |
| 2381 | |
| 2382 | However, the developers of Perl 5.004 could not fix this bug completely, |
| 2383 | because at least two widely-used modules depend on the old meaning of |
| 2384 | "$$0" in a string. So Perl 5.004 still interprets "$$<digit>" in the |
| 2385 | old (broken) way inside strings; but it generates this message as a |
| 2386 | warning. And in Perl 5.005, this special treatment will cease. |
| 2387 | |
| 2388 | =back |
| 2389 | |
| 2390 | =head1 BUGS |
| 2391 | |
| 2392 | If you find what you think is a bug, you might check the |
| 2393 | articles recently posted to the comp.lang.perl.misc newsgroup. |
| 2394 | There may also be information at http://www.perl.com/perl/, the Perl |
| 2395 | Home Page. |
| 2396 | |
| 2397 | If you believe you have an unreported bug, please run the B<perlbug> |
| 2398 | program included with your release. Make sure to trim your bug down |
| 2399 | to a tiny but sufficient test case. Your bug report, along with the |
| 2400 | output of C<perl -V>, will be sent off to perlbug@perl.com to be |
| 2401 | analysed by the Perl porting team. |
| 2402 | |
| 2403 | =head1 SEE ALSO |
| 2404 | |
| 2405 | The F<Changes> file for exhaustive details on what changed. |
| 2406 | |
| 2407 | The F<INSTALL> file for how to build Perl. |
| 2408 | |
| 2409 | The F<README> file for general stuff. |
| 2410 | |
| 2411 | The F<Artistic> and F<Copying> files for copyright information. |
| 2412 | |
| 2413 | =head1 HISTORY |
| 2414 | |
| 2415 | Written by Gurusamy Sarathy <F<gsar@activestate.com>>, with many |
| 2416 | contributions from The Perl Porters. |
| 2417 | |
| 2418 | Send omissions or corrections to <F<perlbug@perl.com>>. |
| 2419 | |
| 2420 | =cut |