1PERL5005DELTA(1) Perl Programmers Reference Guide PERL5005DELTA(1)
2
6 perl5005delta - what's new for perl5.005
7
9 This document describes differences between the 5.004 release and this
10 one.
11
13 Perl is now developed on two tracks: a maintenance track that makes
14 small, safe updates to released production versions with emphasis on
15 compatibility; and a development track that pursues more aggressive
16 evolution. Maintenance releases (which should be considered production
17 quality) have subversion numbers that run from 1 to 49, and development
18 releases (which should be considered "alpha" quality) run from 50 to
19 99.
20 Perl 5.005 is the combined product of the new dual-track development
22 scheme.
23
25 WARNING: This version is not binary compatible with Perl 5.004.
26 Starting with Perl 5.004_50 there were many deep and far-reaching
27 changes to the language internals. If you have dynamically loaded
28 extensions that you built under perl 5.003 or 5.004, you can continue
29 to use them with 5.004, but you will need to rebuild and reinstall
30 those extensions to use them 5.005. See INSTALL for detailed
31 instructions on how to upgrade.
32 Default installation structure has changed
34 The new Configure defaults are designed to allow a smooth upgrade from
35 5.004 to 5.005, but you should read INSTALL for a detailed discussion
36 of the changes in order to adapt them to your system.
37 Perl Source Compatibility
39 When none of the experimental features are enabled, there should be
40 very few user-visible Perl source compatibility issues.
41 If threads are enabled, then some caveats apply. @_ and $_ become
43 lexical variables. The effect of this should be largely transparent to
44 the user, but there are some boundary conditions under which user will
45 need to be aware of the issues. For example, local(@_) results in a
46 "Can't localize lexical variable @_ ..." message. This may be enabled
47 in a future version.
48 Some new keywords have been introduced. These are generally expected
50 to have very little impact on compatibility. See "New "INIT" keyword",
51 "New "lock" keyword", and "New "qr//" operator".
52 Certain barewords are now reserved. Use of these will provoke a
54 warning if you have asked for them with the "-w" switch. See ""our" is
55 now a reserved word".
56 C Source Compatibility
58 There have been a large number of changes in the internals to support
59 the new features in this release.
60 • Core sources now require ANSI C compiler
62 An ANSI C compiler is now required to build perl. See INSTALL.
64 • All Perl global variables must now be referenced with an explicit
66 prefix
67 All Perl global variables that are visible for use by extensions
69 now have a "PL_" prefix. New extensions should "not" refer to perl
70 globals by their unqualified names. To preserve sanity, we provide
71 limited backward compatibility for globals that are being widely
72 used like "sv_undef" and "na" (which should now be written as
73 "PL_sv_undef", "PL_na" etc.)
74 If you find that your XS extension does not compile anymore because
76 a perl global is not visible, try adding a "PL_" prefix to the
77 global and rebuild.
78 It is strongly recommended that all functions in the Perl API that
80 don't begin with "perl" be referenced with a "Perl_" prefix. The
81 bare function names without the "Perl_" prefix are supported with
82 macros, but this support may cease in a future release.
83 See perlapi.
85 • Enabling threads has source compatibility issues
87 Perl built with threading enabled requires extensions to use the
89 new "dTHR" macro to initialize the handle to access per-thread
90 data. If you see a compiler error that talks about the variable
91 "thr" not being declared (when building a module that has XS code),
92 you need to add "dTHR;" at the beginning of the block that elicited
93 the error.
94 The API function "perl_get_sv("@",GV_ADD)" should be used instead
96 of directly accessing perl globals as GvSV(errgv). The API call is
97 backward compatible with existing perls and provides source
98 compatibility with threading is enabled.
99 See "C Source Compatibility" for more information.
101 Binary Compatibility
103 This version is NOT binary compatible with older versions. All
104 extensions will need to be recompiled. Further binaries built with
105 threads enabled are incompatible with binaries built without. This
106 should largely be transparent to the user, as all binary incompatible
107 configurations have their own unique architecture name, and extension
108 binaries get installed at unique locations. This allows coexistence of
109 several configurations in the same directory hierarchy. See INSTALL.
110 Security fixes may affect compatibility
112 A few taint leaks and taint omissions have been corrected. This may
113 lead to "failure" of scripts that used to work with older versions.
114 Compiling with -DINCOMPLETE_TAINTS provides a perl with minimal amounts
115 of changes to the tainting behavior. But note that the resulting perl
116 will have known insecurities.
117 Oneliners with the "-e" switch do not create temporary files anymore.
119 Relaxed new mandatory warnings introduced in 5.004
121 Many new warnings that were introduced in 5.004 have been made
122 optional. Some of these warnings are still present, but perl's new
123 features make them less often a problem. See "New Diagnostics".
124 Licensing
126 Perl has a new Social Contract for contributors. See Porting/Contract.
127 The license included in much of the Perl documentation has changed.
129 Most of the Perl documentation was previously under the implicit GNU
130 General Public License or the Artistic License (at the user's choice).
131 Now much of the documentation unambiguously states the terms under
132 which it may be distributed. Those terms are in general much less
133 restrictive than the GNU GPL. See perl and the individual perl
134 manpages listed therein.
135
137 Threads
138 WARNING: Threading is considered an experimental feature. Details of
139 the implementation may change without notice. There are known
140 limitations and some bugs. These are expected to be fixed in future
141 versions.
142 See README.threads.
144 Compiler
146 WARNING: The Compiler and related tools are considered experimental.
147 Features may change without notice, and there are known limitations and
148 bugs. Since the compiler is fully external to perl, the default
149 configuration will build and install it.
150 The Compiler produces three different types of transformations of a
152 perl program. The C backend generates C code that captures perl's
153 state just before execution begins. It eliminates the compile-time
154 overheads of the regular perl interpreter, but the run-time performance
155 remains comparatively the same. The CC backend generates optimized C
156 code equivalent to the code path at run-time. The CC backend has
157 greater potential for big optimizations, but only a few optimizations
158 are implemented currently. The Bytecode backend generates a platform
159 independent bytecode representation of the interpreter's state just
160 before execution. Thus, the Bytecode back end also eliminates much of
161 the compilation overhead of the interpreter.
162 The compiler comes with several valuable utilities.
164 "B::Lint" is an experimental module to detect and warn about suspicious
166 code, especially the cases that the "-w" switch does not detect.
167 "B::Deparse" can be used to demystify perl code, and understand how
169 perl optimizes certain constructs.
170 "B::Xref" generates cross reference reports of all definition and use
172 of variables, subroutines and formats in a program.
173 "B::Showlex" show the lexical variables used by a subroutine or file at
175 a glance.
176 "perlcc" is a simple frontend for compiling perl.
178 See "ext/B/README", B, and the respective compiler modules.
180 Regular Expressions
182 Perl's regular expression engine has been seriously overhauled, and
183 many new constructs are supported. Several bugs have been fixed.
184 Here is an itemized summary:
186 Many new and improved optimizations
188 Changes in the RE engine:
189 Unneeded nodes removed;
191 Substrings merged together;
192 New types of nodes to process (SUBEXPR)* and similar expressions
193 quickly, used if the SUBEXPR has no side effects and matches
194 strings of the same length;
195 Better optimizations by lookup for constant substrings;
196 Better search for constants substrings anchored by $ ;
197 Changes in Perl code using RE engine:
199 More optimizations to s/longer/short/;
201 study() was not working;
202 /blah/ may be optimized to an analogue of index() if $& $` $' not seen;
203 Unneeded copying of matched-against string removed;
204 Only matched part of the string is copying if $` $' were not seen;
205 Many bug fixes
207 Note that only the major bug fixes are listed here. See Changes
208 for others.
209 Backtracking might not restore start of $3.
211 No feedback if max count for * or + on "complex" subexpression
212 was reached, similarly (but at compile time) for {3,34567}
213 Primitive restrictions on max count introduced to decrease a
214 possibility of a segfault;
215 (ZERO-LENGTH)* could segfault;
216 (ZERO-LENGTH)* was prohibited;
217 Long REs were not allowed;
218 /RE/g could skip matches at the same position after a
219 zero-length match;
220 New regular expression constructs
222 The following new syntax elements are supported:
223 (?<=RE)
225 (?<!RE)
226 (?{ CODE })
227 (?i-x)
228 (?i:RE)
229 (?(COND)YES_RE|NO_RE)
230 (?>RE)
231 \z
232 New operator for precompiled regular expressions
234 See "New "qr//" operator".
235 Other improvements
237 Better debugging output (possibly with colors),
238 even from non-debugging Perl;
239 RE engine code now looks like C, not like assembler;
240 Behaviour of RE modifiable by `use re' directive;
241 Improved documentation;
242 Test suite significantly extended;
243 Syntax [:^upper:] etc., reserved inside character classes;
244 Incompatible changes
246 (?i) localized inside enclosing group;
247 $( is not interpolated into RE any more;
248 /RE/g may match at the same position (with non-zero length)
249 after a zero-length match (bug fix).
250 See perlre and perlop.
252 Improved malloc()
254 See banner at the beginning of "malloc.c" for details.
255 Quicksort is internally implemented
257 Perl now contains its own highly optimized qsort() routine. The new
258 qsort() is resistant to inconsistent comparison functions, so Perl's
259 sort() will not provoke coredumps any more when given poorly written
260 sort subroutines. (Some C library qsort()s that were being used before
261 used to have this problem.) In our testing, the new qsort() required
262 the minimal number of pair-wise compares on average, among all known
263 qsort() implementations.
264 See "perlfunc/sort".
266 Reliable signals
268 Perl's signal handling is susceptible to random crashes, because
269 signals arrive asynchronously, and the Perl runtime is not reentrant at
270 arbitrary times.
271 However, one experimental implementation of reliable signals is
273 available when threads are enabled. See "Thread::Signal". Also see
274 INSTALL for how to build a Perl capable of threads.
275 Reliable stack pointers
277 The internals now reallocate the perl stack only at predictable times.
278 In particular, magic calls never trigger reallocations of the stack,
279 because all reentrancy of the runtime is handled using a "stack of
280 stacks". This should improve reliability of cached stack pointers in
281 the internals and in XSUBs.
282 More generous treatment of carriage returns
284 Perl used to complain if it encountered literal carriage returns in
285 scripts. Now they are mostly treated like whitespace within program
286 text. Inside string literals and here documents, literal carriage
287 returns are ignored if they occur paired with linefeeds, or get
288 interpreted as whitespace if they stand alone. This behavior means
289 that literal carriage returns in files should be avoided. You can get
290 the older, more compatible (but less generous) behavior by defining the
291 preprocessor symbol "PERL_STRICT_CR" when building perl. Of course,
292 all this has nothing whatever to do with how escapes like "\r" are
293 handled within strings.
294 Note that this doesn't somehow magically allow you to keep all text
296 files in DOS format. The generous treatment only applies to files that
297 perl itself parses. If your C compiler doesn't allow carriage returns
298 in files, you may still be unable to build modules that need a C
299 compiler.
300 Memory leaks
302 "substr", "pos" and "vec" don't leak memory anymore when used in lvalue
303 context. Many small leaks that impacted applications that embed
304 multiple interpreters have been fixed.
305 Better support for multiple interpreters
307 The build-time option "-DMULTIPLICITY" has had many of the details
308 reworked. Some previously global variables that should have been per-
309 interpreter now are. With care, this allows interpreters to call each
310 other. See the "PerlInterp" extension on CPAN.
311 Behavior of local() on array and hash elements is now well-defined
313 See "Temporary Values via local()" in perlsub.
314 "%!" is transparently tied to the Errno module
316 See perlvar, and Errno.
317 Pseudo-hashes are supported
319 See perlref.
320 "EXPR foreach EXPR" is supported
322 See perlsyn.
323 Keywords can be globally overridden
325 See perlsub.
326 $^E is meaningful on Win32
328 See perlvar.
329 "foreach (1..1000000)" optimized
331 "foreach (1..1000000)" is now optimized into a counting loop. It does
332 not try to allocate a 1000000-size list anymore.
333 "Foo::" can be used as implicitly quoted package name
335 Barewords caused unintuitive behavior when a subroutine with the same
336 name as a package happened to be defined. Thus, "new Foo @args", use
337 the result of the call to Foo() instead of "Foo" being treated as a
338 literal. The recommended way to write barewords in the indirect object
339 slot is "new Foo:: @args". Note that the method new() is called with a
340 first argument of "Foo", not "Foo::" when you do that.
341 "exists $Foo::{Bar::}" tests existence of a package
343 It was impossible to test for the existence of a package without
344 actually creating it before. Now "exists $Foo::{Bar::}" can be used to
345 test if the "Foo::Bar" namespace has been created.
346 Better locale support
348 See perllocale.
349 Experimental support for 64-bit platforms
351 Perl5 has always had 64-bit support on systems with 64-bit longs.
352 Starting with 5.005, the beginnings of experimental support for systems
353 with 32-bit long and 64-bit 'long long' integers has been added. If
354 you add -DUSE_LONG_LONG to your ccflags in config.sh (or manually
355 define it in perl.h) then perl will be built with 'long long' support.
356 There will be many compiler warnings, and the resultant perl may not
357 work on all systems. There are many other issues related to third-
358 party extensions and libraries. This option exists to allow people to
359 work on those issues.
360 prototype() returns useful results on builtins
362 See "prototype" in perlfunc.
363 Extended support for exception handling
365 die() now accepts a reference value, and $@ gets set to that value in
366 exception traps. This makes it possible to propagate exception
367 objects. This is an undocumented experimental feature.
368 Re-blessing in DESTROY() supported for chaining DESTROY() methods
370 See "Destructors" in perlobj.
371 All "printf" format conversions are handled internally
373 See "printf" in perlfunc.
374 New "INIT" keyword
376 "INIT" subs are like "BEGIN" and "END", but they get run just before
377 the perl runtime begins execution. e.g., the Perl Compiler makes use
378 of "INIT" blocks to initialize and resolve pointers to XSUBs.
379 New "lock" keyword
381 The "lock" keyword is the fundamental synchronization primitive in
382 threaded perl. When threads are not enabled, it is currently a noop.
383 To minimize impact on source compatibility this keyword is "weak",
385 i.e., any user-defined subroutine of the same name overrides it, unless
386 a "use Thread" has been seen.
387 New "qr//" operator
389 The "qr//" operator, which is syntactically similar to the other quote-
390 like operators, is used to create precompiled regular expressions.
391 This compiled form can now be explicitly passed around in variables,
392 and interpolated in other regular expressions. See perlop.
393 "our" is now a reserved word
395 Calling a subroutine with the name "our" will now provoke a warning
396 when using the "-w" switch.
397 Tied arrays are now fully supported
399 See Tie::Array.
400 Tied handles support is better
402 Several missing hooks have been added. There is also a new base class
403 for TIEARRAY implementations. See Tie::Array.
404 4th argument to substr
406 substr() can now both return and replace in one operation. The
407 optional 4th argument is the replacement string. See "substr" in
408 perlfunc.
409 Negative LENGTH argument to splice
411 splice() with a negative LENGTH argument now work similar to what the
412 LENGTH did for substr(). Previously a negative LENGTH was treated as
413 0. See "splice" in perlfunc.
414 Magic lvalues are now more magical
416 When you say something like "substr($x, 5) = "hi"", the scalar returned
417 by substr() is special, in that any modifications to it affect $x.
418 (This is called a 'magic lvalue' because an 'lvalue' is something on
419 the left side of an assignment.) Normally, this is exactly what you
420 would expect to happen, but Perl uses the same magic if you use
421 substr(), pos(), or vec() in a context where they might be modified,
422 like taking a reference with "\" or as an argument to a sub that
423 modifies @_. In previous versions, this 'magic' only went one way, but
424 now changes to the scalar the magic refers to ($x in the above example)
425 affect the magic lvalue too. For instance, this code now acts
426 differently:
427 $x = "hello";
429 sub printit {
430 $x = "g'bye";
431 print $_[0], "\n";
432 }
433 printit(substr($x, 0, 5));
434 In previous versions, this would print "hello", but it now prints
436 "g'bye".
437 <> now reads in records
439 If $/ is a reference to an integer, or a scalar that holds an integer,
440 <> will read in records instead of lines. For more info, see "$/" in
441 perlvar.
442
444 Configure has many incremental improvements. Site-wide policy for
445 building perl can now be made persistent, via Policy.sh. Configure
446 also records the command-line arguments used in config.sh.
447 New Platforms
449 BeOS is now supported. See README.beos.
450 DOS is now supported under the DJGPP tools. See README.dos (installed
452 as perldos on some systems).
453 MiNT is now supported. See README.mint.
455 MPE/iX is now supported. See README.mpeix.
457 MVS (aka OS390, aka Open Edition) is now supported. See README.os390
459 (installed as perlos390 on some systems).
460 Stratus VOS is now supported. See README.vos.
462 Changes in existing support
464 Win32 support has been vastly enhanced. Support for Perl Object, a C++
465 encapsulation of Perl. GCC and EGCS are now supported on Win32. See
466 README.win32, aka perlwin32.
467 VMS configuration system has been rewritten. See README.vms (installed
469 as README_vms on some systems).
470 The hints files for most Unix platforms have seen incremental
472 improvements.
473
475 New Modules
476 B Perl compiler and tools. See B.
477 Data::Dumper
479 A module to pretty print Perl data. See Data::Dumper.
480 Dumpvalue
482 A module to dump perl values to the screen. See Dumpvalue.
483 Errno
485 A module to look up errors more conveniently. See Errno.
486 File::Spec
488 A portable API for file operations.
489 ExtUtils::Installed
491 Query and manage installed modules.
492 ExtUtils::Packlist
494 Manipulate .packlist files.
495 Fatal
497 Make functions/builtins succeed or die.
498 IPC::SysV
500 Constants and other support infrastructure for System V IPC
501 operations in perl.
502 Test
504 A framework for writing test suites.
505 Tie::Array
507 Base class for tied arrays.
508 Tie::Handle
510 Base class for tied handles.
511 Thread
513 Perl thread creation, manipulation, and support.
514 attrs
516 Set subroutine attributes.
517 fields
519 Compile-time class fields.
520 re Various pragmata to control behavior of regular expressions.
522 Changes in existing modules
524 Benchmark
525 You can now run tests for x seconds instead of guessing the right
526 number of tests to run.
527 Keeps better time.
529 Carp
531 Carp has a new function cluck(). cluck() warns, like carp(), but
532 also adds a stack backtrace to the error message, like confess().
533 CGI CGI has been updated to version 2.42.
535 Fcntl
537 More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for
538 large (more than 4G) file access (the 64-bit support is not yet
539 working, though, so no need to get overly excited),
540 Free/Net/OpenBSD locking behaviour flags F_FLOCK, F_POSIX, Linux
541 F_SHLCK, and O_ACCMODE: the mask of O_RDONLY, O_WRONLY, and O_RDWR.
542 Math::Complex
544 The accessors methods Re, Im, arg, abs, rho, theta, methods can
545 ($z->Re()) now also act as mutators ($z->Re(3)).
546 Math::Trig
548 A little bit of radial trigonometry (cylindrical and spherical)
549 added, for example the great circle distance.
550 POSIX
552 POSIX now has its own platform-specific hints files.
553 DB_File
555 DB_File supports version 2.x of Berkeley DB. See
556 "ext/DB_File/Changes".
557 MakeMaker
559 MakeMaker now supports writing empty makefiles, provides a way to
560 specify that site umask() policy should be honored. There is also
561 better support for manipulation of .packlist files, and getting
562 information about installed modules.
563 Extensions that have both architecture-dependent and architecture-
565 independent files are now always installed completely in the
566 architecture-dependent locations. Previously, the shareable parts
567 were shared both across architectures and across perl versions and
568 were therefore liable to be overwritten with newer versions that
569 might have subtle incompatibilities.
570 CPAN
572 See perlmodinstall and CPAN.
573 Cwd Cwd::cwd is faster on most platforms.
575
577 "h2ph" and related utilities have been vastly overhauled.
578 "perlcc", a new experimental front end for the compiler is available.
580 The crude GNU "configure" emulator is now called "configure.gnu" to
582 avoid trampling on "Configure" under case-insensitive filesystems.
583 "perldoc" used to be rather slow. The slower features are now
585 optional. In particular, case-insensitive searches need the "-i"
586 switch, and recursive searches need "-r". You can set these switches
587 in the "PERLDOC" environment variable to get the old behavior.
588
590 Config.pm now has a glossary of variables.
591 Porting/patching.pod has detailed instructions on how to create and
593 submit patches for perl.
594 perlport specifies guidelines on how to write portably.
596 perlmodinstall describes how to fetch and install modules from "CPAN"
598 sites.
599 Some more Perl traps are documented now. See perltrap.
601 perlopentut gives a tutorial on using open().
603 perlreftut gives a tutorial on references.
605 perlthrtut gives a tutorial on threads.
607
609 Ambiguous call resolved as CORE::%s(), qualify as such or use &
610 (W) A subroutine you have declared has the same name as a Perl
611 keyword, and you have used the name without qualification for
612 calling one or the other. Perl decided to call the builtin because
613 the subroutine is not imported.
614 To force interpretation as a subroutine call, either put an
616 ampersand before the subroutine name, or qualify the name with its
617 package. Alternatively, you can import the subroutine (or pretend
618 that it's imported with the "use subs" pragma).
619 To silently interpret it as the Perl operator, use the "CORE::"
621 prefix on the operator (e.g. CORE::log($x)) or by declaring the
622 subroutine to be an object method (see "attrs").
623 Bad index while coercing array into hash
625 (F) The index looked up in the hash found as the 0'th element of a
626 pseudo-hash is not legal. Index values must be at 1 or greater.
627 See perlref.
628 Bareword "%s" refers to nonexistent package
630 (W) You used a qualified bareword of the form "Foo::", but the
631 compiler saw no other uses of that namespace before that point.
632 Perhaps you need to predeclare a package?
633 Can't call method "%s" on an undefined value
635 (F) You used the syntax of a method call, but the slot filled by
636 the object reference or package name contains an undefined value.
637 Something like this will reproduce the error:
638 $BADREF = 42;
640 process $BADREF 1,2,3;
641 $BADREF->process(1,2,3);
642 Can't check filesystem of script "%s" for nosuid
644 (P) For some reason you can't check the filesystem of the script
645 for nosuid.
646 Can't coerce array into hash
648 (F) You used an array where a hash was expected, but the array has
649 no information on how to map from keys to array indices. You can
650 do that only with arrays that have a hash reference at index 0.
651 Can't goto subroutine from an eval-string
653 (F) The "goto subroutine" call can't be used to jump out of an eval
654 "string". (You can use it to jump out of an eval {BLOCK}, but you
655 probably don't want to.)
656 Can't localize pseudo-hash element
658 (F) You said something like "local $ar->{'key'}", where $ar is a
659 reference to a pseudo-hash. That hasn't been implemented yet, but
660 you can get a similar effect by localizing the corresponding array
661 element directly: "local $ar->[$ar->[0]{'key'}]".
662 Can't use %%! because Errno.pm is not available
664 (F) The first time the %! hash is used, perl automatically loads
665 the Errno.pm module. The Errno module is expected to tie the %!
666 hash to provide symbolic names for $! errno values.
667 Cannot find an opnumber for "%s"
669 (F) A string of a form "CORE::word" was given to prototype(), but
670 there is no builtin with the name "word".
671 Character class syntax [. .] is reserved for future extensions
673 (W) Within regular expression character classes ([]) the syntax
674 beginning with "[." and ending with ".]" is reserved for future
675 extensions. If you need to represent those character sequences
676 inside a regular expression character class, just quote the square
677 brackets with the backslash: "\[." and ".\]".
678 Character class syntax [: :] is reserved for future extensions
680 (W) Within regular expression character classes ([]) the syntax
681 beginning with "[:" and ending with ":]" is reserved for future
682 extensions. If you need to represent those character sequences
683 inside a regular expression character class, just quote the square
684 brackets with the backslash: "\[:" and ":\]".
685 Character class syntax [= =] is reserved for future extensions
687 (W) Within regular expression character classes ([]) the syntax
688 beginning with "[=" and ending with "=]" is reserved for future
689 extensions. If you need to represent those character sequences
690 inside a regular expression character class, just quote the square
691 brackets with the backslash: "\[=" and "=\]".
692 %s: Eval-group in insecure regular expression
694 (F) Perl detected tainted data when trying to compile a regular
695 expression that contains the "(?{ ... })" zero-width assertion,
696 which is unsafe. See "(?{ code })" in perlre, and perlsec.
697 %s: Eval-group not allowed, use re 'eval'
699 (F) A regular expression contained the "(?{ ... })" zero-width
700 assertion, but that construct is only allowed when the "use re
701 'eval'" pragma is in effect. See "(?{ code })" in perlre.
702 %s: Eval-group not allowed at run time
704 (F) Perl tried to compile a regular expression containing the "(?{
705 ... })" zero-width assertion at run time, as it would when the
706 pattern contains interpolated values. Since that is a security
707 risk, it is not allowed. If you insist, you may still do this by
708 explicitly building the pattern from an interpolated string at run
709 time and using that in an eval(). See "(?{ code })" in perlre.
710 Explicit blessing to '' (assuming package main)
712 (W) You are blessing a reference to a zero length string. This has
713 the effect of blessing the reference into the package main. This
714 is usually not what you want. Consider providing a default target
715 package, e.g. bless($ref, $p || 'MyPackage');
716 Illegal hex digit ignored
718 (W) You may have tried to use a character other than 0 - 9 or A - F
719 in a hexadecimal number. Interpretation of the hexadecimal number
720 stopped before the illegal character.
721 No such array field
723 (F) You tried to access an array as a hash, but the field name used
724 is not defined. The hash at index 0 should map all valid field
725 names to array indices for that to work.
726 No such field "%s" in variable %s of type %s
728 (F) You tried to access a field of a typed variable where the type
729 does not know about the field name. The field names are looked up
730 in the %FIELDS hash in the type package at compile time. The
731 %FIELDS hash is usually set up with the 'fields' pragma.
732 Out of memory during ridiculously large request
734 (F) You can't allocate more than 2^31+"small amount" bytes. This
735 error is most likely to be caused by a typo in the Perl program.
736 e.g., $arr[time] instead of $arr[$time].
737 Range iterator outside integer range
739 (F) One (or both) of the numeric arguments to the range operator
740 ".." are outside the range which can be represented by integers
741 internally. One possible workaround is to force Perl to use
742 magical string increment by prepending "0" to your numbers.
743 Recursive inheritance detected while looking for method '%s' %s
745 (F) More than 100 levels of inheritance were encountered while
746 invoking a method. Probably indicates an unintended loop in your
747 inheritance hierarchy.
748 Reference found where even-sized list expected
750 (W) You gave a single reference where Perl was expecting a list
751 with an even number of elements (for assignment to a hash). This
752 usually means that you used the anon hash constructor when you
753 meant to use parens. In any case, a hash requires key/value pairs.
754 %hash = { one => 1, two => 2, }; # WRONG
756 %hash = [ qw/ an anon array / ]; # WRONG
757 %hash = ( one => 1, two => 2, ); # right
758 %hash = qw( one 1 two 2 ); # also fine
759 Undefined value assigned to typeglob
761 (W) An undefined value was assigned to a typeglob, a la "*foo =
762 undef". This does nothing. It's possible that you really mean
763 "undef *foo".
764 Use of reserved word "%s" is deprecated
766 (D) The indicated bareword is a reserved word. Future versions of
767 perl may use it as a keyword, so you're better off either
768 explicitly quoting the word in a manner appropriate for its context
769 of use, or using a different name altogether. The warning can be
770 suppressed for subroutine names by either adding a "&" prefix, or
771 using a package qualifier, e.g. &our(), or Foo::our().
772 perl: warning: Setting locale failed.
774 (S) The whole warning message will look something like:
775 perl: warning: Setting locale failed.
777 perl: warning: Please check that your locale settings:
778 LC_ALL = "En_US",
779 LANG = (unset)
780 are supported and installed on your system.
781 perl: warning: Falling back to the standard locale ("C").
782 Exactly what were the failed locale settings varies. In the above
784 the settings were that the LC_ALL was "En_US" and the LANG had no
785 value. This error means that Perl detected that you and/or your
786 system administrator have set up the so-called variable system but
787 Perl could not use those settings. This was not dead serious,
788 fortunately: there is a "default locale" called "C" that Perl can
789 and will use, the script will be run. Before you really fix the
790 problem, however, you will get the same error message each time you
791 run Perl. How to really fix the problem can be found in "LOCALE
792 PROBLEMS" in perllocale.
793
795 Can't mktemp()
796 (F) The mktemp() routine failed for some reason while trying to
797 process a -e switch. Maybe your /tmp partition is full, or
798 clobbered.
799 Removed because -e doesn't use temporary files any more.
801 Can't write to temp file for -e: %s
803 (F) The write routine failed for some reason while trying to
804 process a -e switch. Maybe your /tmp partition is full, or
805 clobbered.
806 Removed because -e doesn't use temporary files any more.
808 Cannot open temporary file
810 (F) The create routine failed for some reason while trying to
811 process a -e switch. Maybe your /tmp partition is full, or
812 clobbered.
813 Removed because -e doesn't use temporary files any more.
815 regexp too big
817 (F) The current implementation of regular expressions uses shorts
818 as address offsets within a string. Unfortunately this means that
819 if the regular expression compiles to longer than 32767, it'll blow
820 up. Usually when you want a regular expression this big, there is
821 a better way to do it with multiple statements. See perlre.
822
824 You can use "Configure -Uinstallusrbinperl" which causes installperl to
825 skip installing perl also as /usr/bin/perl. This is useful if you
826 prefer not to modify /usr/bin for some reason or another but harmful
827 because many scripts assume to find Perl in /usr/bin/perl.
828
830 If you find what you think is a bug, you might check the headers of
831 recently posted articles in the comp.lang.perl.misc newsgroup. There
832 may also be information at http://www.perl.com/perl/ , the Perl Home
833 Page.
834 If you believe you have an unreported bug, please run the perlbug
836 program included with your release. Make sure you trim your bug down
837 to a tiny but sufficient test case. Your bug report, along with the
838 output of "perl -V", will be sent off to <perlbug@perl.com> to be
839 analysed by the Perl porting team.
840
842 The Changes file for exhaustive details on what changed.
843 The INSTALL file for how to build Perl.
845 The README file for general stuff.
847 The Artistic and Copying files for copyright information.
849
851 Written by Gurusamy Sarathy <gsar@activestate.com>, with many
852 contributions from The Perl Porters.
853 Send omissions or corrections to <perlbug@perl.com>.
855perl v5.38.2 2023-11-30 PERL5005DELTA(1)