3 perldelta - what's new for perl5.005
7 This document describes differences between the 5.004 release and this one.
9 =head1 About the new versioning system
11 Perl is now developed on two tracks: a maintenance track that makes
12 small, safe updates to released production versions with emphasis on
13 compatibility; and a development track that pursues more aggressive
14 evolution. Maintenance releases (which should be considered production
15 quality) have subversion numbers that run from C<1> to C<49>, and
16 development releases (which should be considered "alpha" quality) run
19 Perl 5.005 is the combined product of the new dual-track development
22 =head1 Incompatible Changes
24 =head2 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 changes
27 to the language internals. If you have dynamically loaded extensions
28 that you built under perl 5.003 or 5.004, you can continue to use them
29 with 5.004, but you will need to rebuild and reinstall those extensions
30 to use them 5.005. See L<INSTALL> for detailed instructions on how to
33 =head2 Default installation structure has changed
35 The new Configure defaults are designed to allow a smooth upgrade from
36 5.004 to 5.005, but you should read L<INSTALL> for a detailed
37 discussion of the changes in order to adapt them to your system.
39 =head2 Perl Source Compatibility
41 When none of the experimental features are enabled, there should be
42 very few user-visible Perl source compatibility issues.
44 If threads are enabled, then some caveats apply. C<@_> and C<$_> become
45 lexical variables. The effect of this should be largely transparent to
46 the user, but there are some boundary conditions under which user will
47 need to be aware of the issues. For example, C<local(@_)> results in
48 a "Can't localize lexical variable @_ ..." message. This may be enabled
51 Some new keywords have been introduced. These are generally expected to
52 have very little impact on compatibility. See L<New C<INIT> keyword>,
53 L<New C<lock> keyword>, and L<New C<qr//> operator>.
55 Certain barewords are now reserved. Use of these will provoke a warning
56 if you have asked for them with the C<-w> switch.
57 See L<C<our> is now a reserved word>.
59 =head2 C Source Compatibility
61 There have been a large number of changes in the internals to support
62 the new features in this release.
66 =item Core sources now require ANSI C compiler
68 An ANSI C compiler is now B<required> to build perl. See F<INSTALL>.
70 =item All Perl global variables must now be referenced with an explicit prefix
72 All Perl global variables that are visible for use by extensions now
73 have a C<PL_> prefix. New extensions should C<not> refer to perl globals
74 by their unqualified names. To preserve sanity, we provide limited
75 backward compatibility for globals that are being widely used like
76 C<sv_undef> and C<na> (which should now be written as C<PL_sv_undef>,
79 If you find that your XS extension does not compile anymore because a
80 perl global is not visible, try adding a C<PL_> prefix to the global
83 It is strongly recommended that all functions in the Perl API that don't
84 begin with C<perl> be referenced with a C<Perl_> prefix. The bare function
85 names without the C<Perl_> prefix are supported with macros, but this
86 support may cease in a future release.
88 See L<perlguts/"API LISTING">.
90 =item Enabling threads has source compatibility issues
92 Perl built with threading enabled requires extensions to use the new
93 C<dTHR> macro to initialize the handle to access per-thread data.
94 If you see a compiler error that talks about the variable C<thr> not
95 being declared (when building a module that has XS code), you need
96 to add C<dTHR;> at the beginning of the block that elicited the error.
98 The API function C<perl_get_sv("@",FALSE)> should be used instead of
99 directly accessing perl globals as C<GvSV(errgv)>. The API call is
100 backward compatible with existing perls and provides source compatibility
101 with threading is enabled.
103 See L<"C Source Compatibility"> for more information.
107 =head2 Binary Compatibility
109 This version is NOT binary compatible with older versions. All extensions
110 will need to be recompiled. Further binaries built with threads enabled
111 are incompatible with binaries built without. This should largely be
112 transparent to the user, as all binary incompatible configurations have
113 their own unique architecture name, and extension binaries get installed at
114 unique locations. This allows coexistence of several configurations in
115 the same directory hierarchy. See F<INSTALL>.
117 =head2 Security fixes may affect compatibility
119 A few taint leaks and taint omissions have been corrected. This may lead
120 to "failure" of scripts that used to work with older versions. Compiling
121 with -DINCOMPLETE_TAINTS provides a perl with minimal amounts of changes
122 to the tainting behavior. But note that the resulting perl will have
125 Oneliners with the C<-e> switch do not create temporary files anymore.
127 =head2 Relaxed new mandatory warnings introduced in 5.004
129 Many new warnings that were introduced in 5.004 have been made
130 optional. Some of these warnings are still present, but perl's new
131 features make them less often a problem. See L<New Diagnostics>.
135 Perl has a new Social Contract for contributors. See F<Porting/Contract>.
137 The license included in much of the Perl documentation has changed.
138 Most of the Perl documentation was previously under the implicit GNU
139 General Public License or the Artistic License (at the user's choice).
140 Now much of the documentation unambigously states the terms under which
141 it may be distributed. Those terms are in general much less restrictive
142 than the GNU GPL. See L<perl> and the individual perl man pages listed
150 WARNING: Threading is considered an B<experimental> feature. Details of the
151 implementation may change without notice. There are known limitations
152 and some bugs. These are expected to be fixed in future versions.
154 See L<README.threads>.
158 WARNING: The Compiler and related tools are considered B<experimental>.
159 Features may change without notice, and there are known limitations
160 and bugs. Since the compiler is fully external to perl, the default
161 configuration will build and install it.
163 The Compiler produces three different types of transformations of a
164 perl program. The C backend generates C code that captures perl's state
165 just before execution begins. It eliminates the compile-time overheads
166 of the regular perl interpreter, but the run-time performance remains
167 comparatively the same. The CC backend generates optimized C code
168 equivalent to the code path at run-time. The CC backend has greater
169 potential for big optimizations, but only a few optimizations are
170 implemented currently. The Bytecode backend generates a platform
171 independent bytecode representation of the interpreter's state
172 just before execution. Thus, the Bytecode back end also eliminates
173 much of the compilation overhead of the interpreter.
175 The compiler comes with several valuable utilities.
177 C<B::Lint> is an experimental module to detect and warn about suspicious
178 code, especially the cases that the C<-w> switch does not detect.
180 C<B::Deparse> can be used to demystify perl code, and understand
181 how perl optimizes certain constructs.
183 C<B::Xref> generates cross reference reports of all definition and use
184 of variables, subroutines and formats in a program.
186 C<B::Showlex> show the lexical variables used by a subroutine or file
189 C<perlcc> is a simple frontend for compiling perl.
191 See C<ext/B/README>, L<B>, and the respective compiler modules.
193 =head2 Regular Expressions
195 Perl's regular expression engine has been seriously overhauled, and
196 many new constructs are supported. Several bugs have been fixed.
198 Here is an itemized summary:
202 =item Many new and improved optimizations
204 Changes in the RE engine:
206 Unneeded nodes removed;
207 Substrings merged together;
208 New types of nodes to process (SUBEXPR)* and similar expressions
209 quickly, used if the SUBEXPR has no side effects and matches
210 strings of the same length;
211 Better optimizations by lookup for constant substrings;
212 Better search for constants substrings anchored by $ ;
214 Changes in Perl code using RE engine:
216 More optimizations to s/longer/short/;
217 study() was not working;
218 /blah/ may be optimized to an analogue of index() if $& $` $' not seen;
219 Unneeded copying of matched-against string removed;
220 Only matched part of the string is copying if $` $' were not seen;
224 Note that only the major bug fixes are listed here. See F<Changes> for others.
226 Backtracking might not restore start of $3.
227 No feedback if max count for * or + on "complex" subexpression
228 was reached, similarly (but at compile time) for {3,34567}
229 Primitive restrictions on max count introduced to decrease a
230 possibility of a segfault;
231 (ZERO-LENGTH)* could segfault;
232 (ZERO-LENGTH)* was prohibited;
233 Long REs were not allowed;
234 /RE/g could skip matches at the same position after a
237 =item New regular expression constructs
239 The following new syntax elements are supported:
246 (?(COND)YES_RE|NO_RE)
250 =item New operator for precompiled regular expressions
252 See L<New C<qr//> operator>.
254 =item Other improvements
256 Better debugging output (possibly with colors),
257 even from non-debugging Perl;
258 RE engine code now looks like C, not like assembler;
259 Behaviour of RE modifiable by `use re' directive;
260 Improved documentation;
261 Test suite significantly extended;
262 Syntax [:^upper:] etc., reserved inside character classes;
264 =item Incompatible changes
266 (?i) localized inside enclosing group;
267 $( is not interpolated into RE any more;
268 /RE/g may match at the same position (with non-zero length)
269 after a zero-length match (bug fix).
273 See L<perlre> and L<perlop>.
275 =head2 Improved malloc()
277 See banner at the beginning of C<malloc.c> for details.
279 =head2 Quicksort is internally implemented
281 Perl now contains its own highly optimized qsort() routine. The new qsort()
282 is resistant to inconsistent comparison functions, so Perl's C<sort()> will
283 not provoke coredumps any more when given poorly written sort subroutines.
284 (Some C library C<qsort()>s that were being used before used to have this
285 problem.) In our testing, the new C<qsort()> required the minimal number
286 of pair-wise compares on average, among all known C<qsort()> implementations.
288 See C<perlfunc/sort>.
290 =head2 Reliable signals
292 Perl's signal handling is susceptible to random crashes, because signals
293 arrive asynchronously, and the Perl runtime is not reentrant at arbitrary
296 However, one experimental implementation of reliable signals is available
297 when threads are enabled. See C<Thread::Signal>. Also see F<INSTALL> for
298 how to build a Perl capable of threads.
300 =head2 Reliable stack pointers
302 The internals now reallocate the perl stack only at predictable times.
303 In particular, magic calls never trigger reallocations of the stack,
304 because all reentrancy of the runtime is handled using a "stack of stacks".
305 This should improve reliability of cached stack pointers in the internals
308 =head2 More generous treatment of carriage returns
310 Perl used to complain if it encountered literal carriage returns in
311 scripts. Now they are mostly treated like whitespace within program text.
312 Inside string literals and here documents, literal carriage returns are
313 ignored if they occur paired with newlines, or get interpreted as newlines
314 if they stand alone. This behavior means that literal carriage returns
315 in files should be avoided. You can get the older, more compatible (but
316 less generous) behavior by defining the preprocessor symbol
317 C<PERL_STRICT_CR> when building perl. Of course, all this has nothing
318 whatever to do with how escapes like C<\r> are handled within strings.
320 Note that this doesn't somehow magically allow you to keep all text files
321 in DOS format. The generous treatment only applies to files that perl
322 itself parses. If your C compiler doesn't allow carriage returns in
323 files, you may still be unable to build modules that need a C compiler.
327 C<substr>, C<pos> and C<vec> don't leak memory anymore when used in lvalue
328 context. Many small leaks that impacted applications that embed multiple
329 interpreters have been fixed.
331 =head2 Better support for multiple interpreters
333 The build-time option C<-DMULTIPLICITY> has had many of the details
334 reworked. Some previously global variables that should have been
335 per-interpreter now are. With care, this allows interpreters to call
336 each other. See the C<PerlInterp> extension on CPAN.
338 =head2 Behavior of local() on array and hash elements is now well-defined
340 See L<perlsub/"Temporary Values via local()">.
342 =head2 C<%!> is transparently tied to the L<Errno> module
344 See L<perlvar>, and L<Errno>.
346 =head2 Pseudo-hashes are supported
350 =head2 C<EXPR foreach EXPR> is supported
354 =head2 Keywords can be globally overridden
358 =head2 C<$^E> is meaningful on Win32
362 =head2 C<foreach (1..1000000)> optimized
364 C<foreach (1..1000000)> is now optimized into a counting loop. It does
365 not try to allocate a 1000000-size list anymore.
367 =head2 C<Foo::> can be used as implicitly quoted package name
369 Barewords caused unintuitive behavior when a subroutine with the same
370 name as a package happened to be defined. Thus, C<new Foo @args>,
371 use the result of the call to C<Foo()> instead of C<Foo> being treated
372 as a literal. The recommended way to write barewords in the indirect
373 object slot is C<new Foo:: @args>. Note that the method C<new()> is
374 called with a first argument of C<Foo>, not C<Foo::> when you do that.
376 =head2 C<exists $Foo::{Bar::}> tests existence of a package
378 It was impossible to test for the existence of a package without
379 actually creating it before. Now C<exists $Foo::{Bar::}> can be
380 used to test if the C<Foo::Bar> namespace has been created.
382 =head2 Better locale support
386 =head2 Experimental support for 64-bit platforms
388 Perl5 has always had 64-bit support on systems with 64-bit longs.
389 Starting with 5.005, the beginnings of experimental support for systems
390 with 32-bit long and 64-bit 'long long' integers has been added.
391 If you add -DUSE_LONG_LONG to your ccflags in config.sh (or manually
392 define it in perl.h) then perl will be built with 'long long' support.
393 There will be many compiler warnings, and the resultant perl may not
394 work on all systems. There are many other issues related to
395 third-party extensions and libraries. This option exists to allow
396 people to work on those issues.
398 =head2 prototype() returns useful results on builtins
400 See L<perlfunc/prototype>.
402 =head2 Extended support for exception handling
404 C<die()> now accepts a reference value, and C<$@> gets set to that
405 value in exception traps. This makes it possible to propagate
406 exception objects. This is an undocumented B<experimental> feature.
408 =head2 Re-blessing in DESTROY() supported for chaining DESTROY() methods
410 See L<perlobj/Destructors>.
412 =head2 All C<printf> format conversions are handled internally
414 See L<perlfunc/printf>.
416 =head2 New C<INIT> keyword
418 C<INIT> subs are like C<BEGIN> and C<END>, but they get run just before
419 the perl runtime begins execution. e.g., the Perl Compiler makes use of
420 C<INIT> blocks to initialize and resolve pointers to XSUBs.
422 =head2 New C<lock> keyword
424 The C<lock> keyword is the fundamental synchronization primitive
425 in threaded perl. When threads are not enabled, it is currently a noop.
427 To minimize impact on source compatibility this keyword is "weak", i.e., any
428 user-defined subroutine of the same name overrides it, unless a C<use Thread>
431 =head2 New C<qr//> operator
433 The C<qr//> operator, which is syntactically similar to the other quote-like
434 operators, is used to create precompiled regular expressions. This compiled
435 form can now be explicitly passed around in variables, and interpolated in
436 other regular expressions. See L<perlop>.
438 =head2 C<our> is now a reserved word
440 Calling a subroutine with the name C<our> will now provoke a warning when
441 using the C<-w> switch.
443 =head2 Tied arrays are now fully supported
447 =head2 Tied handles support is better
449 Several missing hooks have been added. There is also a new base class for
450 TIEARRAY implementations. See L<Tie::Array>.
452 =head2 4th argument to substr
454 substr() can now both return and replace in one operation. The optional
455 4th argument is the replacement string. See L<perlfunc/substr>.
457 =head2 Negative LENGTH argument to splice
459 splice() with a negative LENGTH argument now work similar to what the
460 LENGTH did for substr(). Previously a negative LENGTH was treated as
461 0. See L<perlfunc/splice>.
463 =head2 Magic lvalues are now more magical
465 When you say something like C<substr($x, 5) = "hi">, the scalar returned
466 by substr() is special, in that any modifications to it affect $x.
467 (This is called a 'magic lvalue' because an 'lvalue' is something on
468 the left side of an assignment.) Normally, this is exactly what you
469 would expect to happen, but Perl uses the same magic if you use substr(),
470 pos(), or vec() in a context where they might be modified, like taking
471 a reference with C<\> or as an argument to a sub that modifies C<@_>.
472 In previous versions, this 'magic' only went one way, but now changes
473 to the scalar the magic refers to ($x in the above example) affect the
474 magic lvalue too. For instance, this code now acts differently:
481 printit(substr($x, 0, 5));
483 In previous versions, this would print "hello", but it now prints "g'bye".
485 =head2 E<lt>E<gt> now reads in records
487 If C<$/> is a referenence to an integer, or a scalar that holds an integer,
488 E<lt>E<gt> will read in records instead of lines. For more info, see
491 =head1 Supported Platforms
493 Configure has many incremental improvements. Site-wide policy for building
494 perl can now be made persistent, via Policy.sh. Configure also records
495 the command-line arguments used in F<config.sh>.
499 BeOS is now supported. See L<README.beos>.
501 DOS is now supported under the DJGPP tools. See L<README.dos>.
503 MPE/iX is now supported. See L<README.mpeix>.
505 MVS (aka OS390, aka Open Edition) is now supported. See L<README.os390>.
507 Stratus VOS is now supported. See L<README.vos>.
509 =head2 Changes in existing support
511 Win32 support has been vastly enhanced. Support for Perl Object, a C++
512 encapsulation of Perl. GCC and EGCS are now supported on Win32.
513 See F<README.win32>, aka L<perlwin32>.
515 VMS configuration system has been rewritten. See L<README.vms>.
517 The hints files for most Unix platforms have seen incremental improvements.
519 =head1 Modules and Pragmata
527 Perl compiler and tools. See L<B>.
531 A module to pretty print Perl data. See L<Data::Dumper>.
535 A module to look up errors more conveniently. See L<Errno>.
539 A portable API for file operations.
541 =item ExtUtils::Installed
543 Query and manage installed modules.
545 =item ExtUtils::Packlist
547 Manipulate .packlist files.
551 Make functions/builtins succeed or die.
555 Constants and other support infrastructure for System V IPC operations
560 A framework for writing testsuites.
564 Base class for tied arrays.
568 Base class for tied handles.
572 Perl thread creation, manipulation, and support.
576 Set subroutine attributes.
580 Compile-time class fields.
584 Various pragmata to control behavior of regular expressions.
588 =head2 Changes in existing modules
594 You can now run tests for I<x> seconds instead of guessing the right
595 number of tests to run.
599 CGI has been updated to version 2.42.
603 More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for
604 large (more than 4G) file access (the 64-bit support is not yet
605 working, though, so no need to get overly excited), Free/Net/OpenBSD
606 locking behaviour flags F_FLOCK, F_POSIX, Linux F_SHLCK, and
607 O_ACCMODE: the mask of O_RDONLY, O_WRONLY, and O_RDWR.
611 The accessors methods Re, Im, arg, abs, rho, theta, methods can
612 ($z->Re()) now also act as mutators ($z->Re(3)).
616 A little bit of radial trigonometry (cylindrical and spherical) added,
617 for example the great circle distance.
621 POSIX now has its own platform-specific hints files.
625 DB_File supports version 2.x of Berkeley DB. See C<ext/DB_File/Changes>.
629 MakeMaker now supports writing empty makefiles, provides a way to
630 specify that site umask() policy should be honored. There is also
631 better support for manipulation of .packlist files, and getting
632 information about installed modules.
634 Extensions that have both architecture-dependent and
635 architecture-independent files are now always installed completely in
636 the architecture-dependent locations. Previously, the shareable parts
637 were shared both across architectures and across perl versions and were
638 therefore liable to be overwritten with newer versions that might have
639 subtle incompatibilities.
643 See <perlmodinstall> and L<CPAN>.
647 Cwd::cwd is faster on most platforms.
655 =head1 Utility Changes
657 C<h2ph> and related utilities have been vastly overhauled.
659 C<perlcc>, a new experimental front end for the compiler is available.
661 The crude GNU C<configure> emulator is now called C<configure.gnu> to
662 avoid trampling on C<Configure> under case-insensitive filesystems.
664 C<perldoc> used to be rather slow. The slower features are now optional.
665 In particular, case-insensitive searches need the C<-i> switch, and
666 recursive searches need C<-r>. You can set these switches in the
667 C<PERLDOC> environment variable to get the old behavior.
669 =head1 Documentation Changes
671 Config.pm now has a glossary of variables.
673 F<Porting/patching.pod> has detailed instructions on how to create and
674 submit patches for perl.
676 L<perlport> specifies guidelines on how to write portably.
678 L<perlmodinstall> describes how to fetch and install modules from C<CPAN>
681 Some more Perl traps are documented now. See L<perltrap>.
683 =head1 New Diagnostics
687 =item Ambiguous call resolved as CORE::%s(), qualify as such or use &
689 (W) A subroutine you have declared has the same name as a Perl keyword,
690 and you have used the name without qualification for calling one or the
691 other. Perl decided to call the builtin because the subroutine is
694 To force interpretation as a subroutine call, either put an ampersand
695 before the subroutine name, or qualify the name with its package.
696 Alternatively, you can import the subroutine (or pretend that it's
697 imported with the C<use subs> pragma).
699 To silently interpret it as the Perl operator, use the C<CORE::> prefix
700 on the operator (e.g. C<CORE::log($x)>) or by declaring the subroutine
701 to be an object method (see L<attrs>).
703 =item Bad index while coercing array into hash
705 (F) The index looked up in the hash found as the 0'th element of a
706 pseudo-hash is not legal. Index values must be at 1 or greater.
709 =item Bareword "%s" refers to nonexistent package
711 (W) You used a qualified bareword of the form C<Foo::>, but
712 the compiler saw no other uses of that namespace before that point.
713 Perhaps you need to predeclare a package?
715 =item Can't call method "%s" on an undefined value
717 (F) You used the syntax of a method call, but the slot filled by the
718 object reference or package name contains an undefined value.
719 Something like this will reproduce the error:
722 process $BADREF 1,2,3;
723 $BADREF->process(1,2,3);
725 =item Can't coerce array into hash
727 (F) You used an array where a hash was expected, but the array has no
728 information on how to map from keys to array indices. You can do that
729 only with arrays that have a hash reference at index 0.
731 =item Can't goto subroutine from an eval-string
733 (F) The "goto subroutine" call can't be used to jump out of an eval "string".
734 (You can use it to jump out of an eval {BLOCK}, but you probably don't want to.)
736 =item Can't localize pseudo-hash element
738 (F) You said something like C<local $ar-E<gt>{'key'}>, where $ar is
739 a reference to a pseudo-hash. That hasn't been implemented yet, but
740 you can get a similar effect by localizing the corresponding array
741 element directly -- C<local $ar-E<gt>[$ar-E<gt>[0]{'key'}]>.
743 =item Can't use %%! because Errno.pm is not available
745 (F) The first time the %! hash is used, perl automatically loads the
746 Errno.pm module. The Errno module is expected to tie the %! hash to
747 provide symbolic names for C<$!> errno values.
749 =item Cannot find an opnumber for "%s"
751 (F) A string of a form C<CORE::word> was given to prototype(), but
752 there is no builtin with the name C<word>.
754 =item Character class syntax [. .] is reserved for future extensions
756 (W) Within regular expression character classes ([]) the syntax beginning
757 with "[." and ending with ".]" is reserved for future extensions.
758 If you need to represent those character sequences inside a regular
759 expression character class, just quote the square brackets with the
760 backslash: "\[." and ".\]".
762 =item Character class syntax [: :] is reserved for future extensions
764 (W) Within regular expression character classes ([]) the syntax beginning
765 with "[:" and ending with ":]" is reserved for future extensions.
766 If you need to represent those character sequences inside a regular
767 expression character class, just quote the square brackets with the
768 backslash: "\[:" and ":\]".
770 =item Character class syntax [= =] is reserved for future extensions
772 (W) Within regular expression character classes ([]) the syntax
773 beginning with "[=" and ending with "=]" is reserved for future extensions.
774 If you need to represent those character sequences inside a regular
775 expression character class, just quote the square brackets with the
776 backslash: "\[=" and "=\]".
778 =item %s: Eval-group in insecure regular expression
780 (F) Perl detected tainted data when trying to compile a regular expression
781 that contains the C<(?{ ... })> zero-width assertion, which is unsafe.
782 See L<perlre/(?{ code })>, and L<perlsec>.
784 =item %s: Eval-group not allowed, use re 'eval'
786 (F) A regular expression contained the C<(?{ ... })> zero-width assertion,
787 but that construct is only allowed when the C<use re 'eval'> pragma is
788 in effect. See L<perlre/(?{ code })>.
790 =item %s: Eval-group not allowed at run time
792 (F) Perl tried to compile a regular expression containing the C<(?{ ... })>
793 zero-width assertion at run time, as it would when the pattern contains
794 interpolated values. Since that is a security risk, it is not allowed.
795 If you insist, you may still do this by explicitly building the pattern
796 from an interpolated string at run time and using that in an eval().
797 See L<perlre/(?{ code })>.
799 =item Explicit blessing to '' (assuming package main)
801 (W) You are blessing a reference to a zero length string. This has
802 the effect of blessing the reference into the package main. This is
803 usually not what you want. Consider providing a default target
804 package, e.g. bless($ref, $p || 'MyPackage');
806 =item Illegal hex digit ignored
808 (W) You may have tried to use a character other than 0 - 9 or A - F in a
809 hexadecimal number. Interpretation of the hexadecimal number stopped
810 before the illegal character.
812 =item No such array field
814 (F) You tried to access an array as a hash, but the field name used is
815 not defined. The hash at index 0 should map all valid field names to
816 array indices for that to work.
818 =item No such field "%s" in variable %s of type %s
820 (F) You tried to access a field of a typed variable where the type
821 does not know about the field name. The field names are looked up in
822 the %FIELDS hash in the type package at compile time. The %FIELDS hash
823 is usually set up with the 'fields' pragma.
825 =item Out of memory during ridiculously large request
827 (F) You can't allocate more than 2^31+"small amount" bytes. This error
828 is most likely to be caused by a typo in the Perl program. e.g., C<$arr[time]>
829 instead of C<$arr[$time]>.
831 =item Range iterator outside integer range
833 (F) One (or both) of the numeric arguments to the range operator ".."
834 are outside the range which can be represented by integers internally.
835 One possible workaround is to force Perl to use magical string
836 increment by prepending "0" to your numbers.
838 =item Recursive inheritance detected while looking for method '%s' in package '%s'
840 (F) More than 100 levels of inheritance were encountered while invoking a
841 method. Probably indicates an unintended loop in your inheritance hierarchy.
843 =item Reference found where even-sized list expected
845 (W) You gave a single reference where Perl was expecting a list with
846 an even number of elements (for assignment to a hash). This
847 usually means that you used the anon hash constructor when you meant
848 to use parens. In any case, a hash requires key/value B<pairs>.
850 %hash = { one => 1, two => 2, }; # WRONG
851 %hash = [ qw/ an anon array / ]; # WRONG
852 %hash = ( one => 1, two => 2, ); # right
853 %hash = qw( one 1 two 2 ); # also fine
855 =item Undefined value assigned to typeglob
857 (W) An undefined value was assigned to a typeglob, a la C<*foo = undef>.
858 This does nothing. It's possible that you really mean C<undef *foo>.
860 =item Use of reserved word "%s" is deprecated
862 (D) The indicated bareword is a reserved word. Future versions of perl
863 may use it as a keyword, so you're better off either explicitly quoting
864 the word in a manner appropriate for its context of use, or using a
865 different name altogether. The warning can be suppressed for subroutine
866 names by either adding a C<&> prefix, or using a package qualifier,
867 e.g. C<&our()>, or C<Foo::our()>.
869 =item perl: warning: Setting locale failed.
871 (S) The whole warning message will look something like:
873 perl: warning: Setting locale failed.
874 perl: warning: Please check that your locale settings:
877 are supported and installed on your system.
878 perl: warning: Falling back to the standard locale ("C").
880 Exactly what were the failed locale settings varies. In the above the
881 settings were that the LC_ALL was "En_US" and the LANG had no value.
882 This error means that Perl detected that you and/or your system
883 administrator have set up the so-called variable system but Perl could
884 not use those settings. This was not dead serious, fortunately: there
885 is a "default locale" called "C" that Perl can and will use, the
886 script will be run. Before you really fix the problem, however, you
887 will get the same error message each time you run Perl. How to really
888 fix the problem can be found in L<perllocale/"LOCALE PROBLEMS">.
893 =head1 Obsolete Diagnostics
899 (F) The mktemp() routine failed for some reason while trying to process
900 a B<-e> switch. Maybe your /tmp partition is full, or clobbered.
902 Removed because B<-e> doesn't use temporary files any more.
904 =item Can't write to temp file for B<-e>: %s
906 (F) The write routine failed for some reason while trying to process
907 a B<-e> switch. Maybe your /tmp partition is full, or clobbered.
909 Removed because B<-e> doesn't use temporary files any more.
911 =item Cannot open temporary file
913 (F) The create routine failed for some reason while trying to process
914 a B<-e> switch. Maybe your /tmp partition is full, or clobbered.
916 Removed because B<-e> doesn't use temporary files any more.
920 (F) The current implementation of regular expressions uses shorts as
921 address offsets within a string. Unfortunately this means that if
922 the regular expression compiles to longer than 32767, it'll blow up.
923 Usually when you want a regular expression this big, there is a better
924 way to do it with multiple statements. See L<perlre>.
928 (F) The current implementation of regular expressions uses shorts as
929 address offsets within a string. Unfortunately this means that if
930 the regular expression compiles to longer than 32767, it'll blow up.
931 Usually when you want a regular expression this big, there is a better
932 way to do it with multiple statements. See L<perlre>.
938 If you find what you think is a bug, you might check the headers of
939 recently posted articles in the comp.lang.perl.misc newsgroup.
940 There may also be information at http://www.perl.com/perl/, the Perl
943 If you believe you have an unreported bug, please run the B<perlbug>
944 program included with your release. Make sure you trim your bug down
945 to a tiny but sufficient test case. Your bug report, along with the
946 output of C<perl -V>, will be sent off to <F<perlbug@perl.com>> to be
947 analysed by the Perl porting team.
951 The F<Changes> file for exhaustive details on what changed.
953 The F<INSTALL> file for how to build Perl.
955 The F<README> file for general stuff.
957 The F<Artistic> and F<Copying> files for copyright information.
961 Written by Gurusamy Sarathy <F<gsar@umich.edu>>, with many contributions
962 from The Perl Porters.
964 Send omissions or corrections to <F<perlbug@perl.com>>.