1PERL56DELTA(1) Perl Programmers Reference Guide PERL56DELTA(1)
2
6 perl56delta - what's new for perl v5.6.0
7
9 This document describes differences between the 5.005 release and the
10 5.6.0 release.
11
13 Interpreter cloning, threads, and concurrency
14 Perl 5.6.0 introduces the beginnings of support for running multiple
16 interpreters concurrently in different threads. In conjunction with
17 the perl_clone() API call, which can be used to selectively duplicate
18 the state of any given interpreter, it is possible to compile a piece
19 of code once in an interpreter, clone that interpreter one or more
20 times, and run all the resulting interpreters in distinct threads.
21 On the Windows platform, this feature is used to emulate fork() at the
23 interpreter level. See perlfork for details about that.
24 This feature is still in evolution. It is eventually meant to be used
26 to selectively clone a subroutine and data reachable from that subrou‐
27 tine in a separate interpreter and run the cloned subroutine in a sepa‐
28 rate thread. Since there is no shared data between the interpreters,
29 little or no locking will be needed (unless parts of the symbol table
30 are explicitly shared). This is obviously intended to be an easy-to-
31 use replacement for the existing threads support.
32 Support for cloning interpreters and interpreter concurrency can be
34 enabled using the -Dusethreads Configure option (see win32/Makefile for
35 how to enable it on Windows.) The resulting perl executable will be
36 functionally identical to one that was built with -Dmultiplicity, but
37 the perl_clone() API call will only be available in the former.
38 -Dusethreads enables the cpp macro USE_ITHREADS by default, which in
40 turn enables Perl source code changes that provide a clear separation
41 between the op tree and the data it operates with. The former is
42 immutable, and can therefore be shared between an interpreter and all
43 of its clones, while the latter is considered local to each inter‐
44 preter, and is therefore copied for each clone.
45 Note that building Perl with the -Dusemultiplicity Configure option is
47 adequate if you wish to run multiple independent interpreters concur‐
48 rently in different threads. -Dusethreads only provides the additional
49 functionality of the perl_clone() API call and other support for run‐
50 ning cloned interpreters concurrently.
51 NOTE: This is an experimental feature. Implementation details are
53 subject to change.
54 Lexically scoped warning categories
56 You can now control the granularity of warnings emitted by perl at a
58 finer level using the "use warnings" pragma. warnings and perllexwarn
59 have copious documentation on this feature.
60 Unicode and UTF-8 support
62 Perl now uses UTF-8 as its internal representation for character
64 strings. The "utf8" and "bytes" pragmas are used to control this sup‐
65 port in the current lexical scope. See perlunicode, utf8 and bytes for
66 more information.
67 This feature is expected to evolve quickly to support some form of I/O
69 disciplines that can be used to specify the kind of input and output
70 data (bytes or characters). Until that happens, additional modules
71 from CPAN will be needed to complete the toolkit for dealing with Uni‐
72 code.
73 NOTE: This should be considered an experimental feature. Implementation
75 details are subject to change.
76 Support for interpolating named characters
78 The new "\N" escape interpolates named characters within strings. For
80 example, "Hi! \N{WHITE SMILING FACE}" evaluates to a string with a uni‐
81 code smiley face at the end.
82 "our" declarations
84 An "our" declaration introduces a value that can be best understood as
86 a lexically scoped symbolic alias to a global variable in the package
87 that was current where the variable was declared. This is mostly use‐
88 ful as an alternative to the "vars" pragma, but also provides the
89 opportunity to introduce typing and other attributes for such vari‐
90 ables. See "our" in perlfunc.
91 Support for strings represented as a vector of ordinals
93 Literals of the form "v1.2.3.4" are now parsed as a string composed of
95 characters with the specified ordinals. This is an alternative, more
96 readable way to construct (possibly unicode) strings instead of inter‐
97 polating characters, as in "\x{1}\x{2}\x{3}\x{4}". The leading "v" may
98 be omitted if there are more than two ordinals, so 1.2.3 is parsed the
99 same as "v1.2.3".
100 Strings written in this form are also useful to represent version "num‐
102 bers". It is easy to compare such version "numbers" (which are really
103 just plain strings) using any of the usual string comparison operators
104 "eq", "ne", "lt", "gt", etc., or perform bitwise string operations on
105 them using "⎪", "&", etc.
106 In conjunction with the new $^V magic variable (which contains the perl
108 version as a string), such literals can be used as a readable way to
109 check if you're running a particular version of Perl:
110 # this will parse in older versions of Perl also
112 if ($^V and $^V gt v5.6.0) {
113 # new features supported
114 }
115 "require" and "use" also have some special magic to support such liter‐
117 als, but this particular usage should be avoided because it leads to
118 misleading error messages under versions of Perl which don't support
119 vector strings. Using a true version number will ensure correct behav‐
120 ior in all versions of Perl:
121 require 5.006; # run time check for v5.6
123 use 5.006_001; # compile time check for v5.6.1
124 Also, "sprintf" and "printf" support the Perl-specific format flag %v
126 to print ordinals of characters in arbitrary strings:
127 printf "v%vd", $^V; # prints current version, such as "v5.5.650"
129 printf "%*vX", ":", $addr; # formats IPv6 address
130 printf "%*vb", " ", $bits; # displays bitstring
131 See "Scalar value constructors" in perldata for additional information.
133 Improved Perl version numbering system
135 Beginning with Perl version 5.6.0, the version number convention has
137 been changed to a "dotted integer" scheme that is more commonly found
138 in open source projects.
139 Maintenance versions of v5.6.0 will be released as v5.6.1, v5.6.2 etc.
141 The next development series following v5.6.0 will be numbered v5.7.x,
142 beginning with v5.7.0, and the next major production release following
143 v5.6.0 will be v5.8.0.
144 The English module now sets $PERL_VERSION to $^V (a string value)
146 rather than $] (a numeric value). (This is a potential incompatibil‐
147 ity. Send us a report via perlbug if you are affected by this.)
148 The v1.2.3 syntax is also now legal in Perl. See "Support for strings
150 represented as a vector of ordinals" for more on that.
151 To cope with the new versioning system's use of at least three signifi‐
153 cant digits for each version component, the method used for increment‐
154 ing the subversion number has also changed slightly. We assume that
155 versions older than v5.6.0 have been incrementing the subversion compo‐
156 nent in multiples of 10. Versions after v5.6.0 will increment them by
157 1. Thus, using the new notation, 5.005_03 is the "same" as v5.5.30,
158 and the first maintenance version following v5.6.0 will be v5.6.1
159 (which should be read as being equivalent to a floating point value of
160 5.006_001 in the older format, stored in $]).
161 New syntax for declaring subroutine attributes
163 Formerly, if you wanted to mark a subroutine as being a method call or
165 as requiring an automatic lock() when it is entered, you had to declare
166 that with a "use attrs" pragma in the body of the subroutine. That can
167 now be accomplished with declaration syntax, like this:
168 sub mymethod : locked method;
170 ...
171 sub mymethod : locked method {
172 ...
173 }
174 sub othermethod :locked :method;
176 ...
177 sub othermethod :locked :method {
178 ...
179 }
180 (Note how only the first ":" is mandatory, and whitespace surrounding
182 the ":" is optional.)
183 AutoSplit.pm and SelfLoader.pm have been updated to keep the attributes
185 with the stubs they provide. See attributes.
186 File and directory handles can be autovivified
188 Similar to how constructs such as "$x->[0]" autovivify a reference,
190 handle constructors (open(), opendir(), pipe(), socketpair(),
191 sysopen(), socket(), and accept()) now autovivify a file or directory
192 handle if the handle passed to them is an uninitialized scalar vari‐
193 able. This allows the constructs such as "open(my $fh, ...)" and
194 "open(local $fh,...)" to be used to create filehandles that will con‐
195 veniently be closed automatically when the scope ends, provided there
196 are no other references to them. This largely eliminates the need for
197 typeglobs when opening filehandles that must be passed around, as in
198 the following example:
199 sub myopen {
201 open my $fh, "@_"
202 or die "Can't open '@_': $!";
203 return $fh;
204 }
205 {
207 my $f = myopen("</etc/motd");
208 print <$f>;
209 # $f implicitly closed here
210 }
211 open() with more than two arguments
213 If open() is passed three arguments instead of two, the second argument
215 is used as the mode and the third argument is taken to be the file
216 name. This is primarily useful for protecting against unintended magic
217 behavior of the traditional two-argument form. See "open" in perlfunc.
218 64-bit support
220 Any platform that has 64-bit integers either
222 (1) natively as longs or ints
224 (2) via special compiler flags
225 (3) using long long or int64_t
226 is able to use "quads" (64-bit integers) as follows:
228 · constants (decimal, hexadecimal, octal, binary) in the code
230 · arguments to oct() and hex()
232 · arguments to print(), printf() and sprintf() (flag prefixes ll, L,
234 q)
235 · printed as such
237 · pack() and unpack() "q" and "Q" formats
239 · in basic arithmetics: + - * / % (NOTE: operating close to the lim‐
241 its of the integer values may produce surprising results)
242 · in bit arithmetics: & ⎪ ^ ~ << >> (NOTE: these used to be forced to
244 be 32 bits wide but now operate on the full native width.)
245 · vec()
247 Note that unless you have the case (a) you will have to configure and
249 compile Perl using the -Duse64bitint Configure flag.
250 NOTE: The Configure flags -Duselonglong and -Duse64bits have been
252 deprecated. Use -Duse64bitint instead.
253 There are actually two modes of 64-bitness: the first one is achieved
255 using Configure -Duse64bitint and the second one using Configure
256 -Duse64bitall. The difference is that the first one is minimal and the
257 second one maximal. The first works in more places than the second.
258 The "use64bitint" does only as much as is required to get 64-bit inte‐
260 gers into Perl (this may mean, for example, using "long longs") while
261 your memory may still be limited to 2 gigabytes (because your pointers
262 could still be 32-bit). Note that the name "64bitint" does not imply
263 that your C compiler will be using 64-bit "int"s (it might, but it
264 doesn't have to): the "use64bitint" means that you will be able to have
265 64 bits wide scalar values.
266 The "use64bitall" goes all the way by attempting to switch also inte‐
268 gers (if it can), longs (and pointers) to being 64-bit. This may cre‐
269 ate an even more binary incompatible Perl than -Duse64bitint: the
270 resulting executable may not run at all in a 32-bit box, or you may
271 have to reboot/reconfigure/rebuild your operating system to be 64-bit
272 aware.
273 Natively 64-bit systems like Alpha and Cray need neither -Duse64bitint
275 nor -Duse64bitall.
276 Last but not least: note that due to Perl's habit of always using
278 floating point numbers, the quads are still not true integers. When
279 quads overflow their limits (0...18_446_744_073_709_551_615 unsigned,
280 -9_223_372_036_854_775_808...9_223_372_036_854_775_807 signed), they
281 are silently promoted to floating point numbers, after which they will
282 start losing precision (in their lower digits).
283 NOTE: 64-bit support is still experimental on most platforms.
285 Existing support only covers the LP64 data model. In particular, the
286 LLP64 data model is not yet supported. 64-bit libraries and system
287 APIs on many platforms have not stabilized--your mileage may vary.
288 Large file support
290 If you have filesystems that support "large files" (files larger than 2
292 gigabytes), you may now also be able to create and access them from
293 Perl.
294 NOTE: The default action is to enable large file support, if
296 available on the platform.
297 If the large file support is on, and you have a Fcntl constant O_LARGE‐
299 FILE, the O_LARGEFILE is automatically added to the flags of sysopen().
300 Beware that unless your filesystem also supports "sparse files" seeking
302 to umpteen petabytes may be inadvisable.
303 Note that in addition to requiring a proper file system to do large
305 files you may also need to adjust your per-process (or your per-system,
306 or per-process-group, or per-user-group) maximum filesize limits before
307 running Perl scripts that try to handle large files, especially if you
308 intend to write such files.
309 Finally, in addition to your process/process group maximum filesize
311 limits, you may have quota limits on your filesystems that stop you
312 (your user id or your user group id) from using large files.
313 Adjusting your process/user/group/file system/operating system limits
315 is outside the scope of Perl core language. For process limits, you
316 may try increasing the limits using your shell's limits/limit/ulimit
317 command before running Perl. The BSD::Resource extension (not included
318 with the standard Perl distribution) may also be of use, it offers the
319 getrlimit/setrlimit interface that can be used to adjust process
320 resource usage limits, including the maximum filesize limit.
321 Long doubles
323 In some systems you may be able to use long doubles to enhance the
325 range and precision of your double precision floating point numbers
326 (that is, Perl's numbers). Use Configure -Duselongdouble to enable
327 this support (if it is available).
328 "more bits"
330 You can "Configure -Dusemorebits" to turn on both the 64-bit support
332 and the long double support.
333 Enhanced support for sort() subroutines
335 Perl subroutines with a prototype of "($$)", and XSUBs in general, can
337 now be used as sort subroutines. In either case, the two elements to
338 be compared are passed as normal parameters in @_. See "sort" in perl‐
339 func.
340 For unprototyped sort subroutines, the historical behavior of passing
342 the elements to be compared as the global variables $a and $b remains
343 unchanged.
344 "sort $coderef @foo" allowed
346 sort() did not accept a subroutine reference as the comparison function
348 in earlier versions. This is now permitted.
349 File globbing implemented internally
351 Perl now uses the File::Glob implementation of the glob() operator
353 automatically. This avoids using an external csh process and the prob‐
354 lems associated with it.
355 NOTE: This is currently an experimental feature. Interfaces and
357 implementation are subject to change.
358 Support for CHECK blocks
360 In addition to "BEGIN", "INIT", "END", "DESTROY" and "AUTOLOAD", sub‐
362 routines named "CHECK" are now special. These are queued up during
363 compilation and behave similar to END blocks, except they are called at
364 the end of compilation rather than at the end of execution. They can‐
365 not be called directly.
366 POSIX character class syntax [: :] supported
368 For example to match alphabetic characters use /[[:alpha:]]/. See
370 perlre for details.
371 Better pseudo-random number generator
373 In 5.005_0x and earlier, perl's rand() function used the C library
375 rand(3) function. As of 5.005_52, Configure tests for drand48(), ran‐
376 dom(), and rand() (in that order) and picks the first one it finds.
377 These changes should result in better random numbers from rand().
379 Improved "qw//" operator
381 The "qw//" operator is now evaluated at compile time into a true list
383 instead of being replaced with a run time call to "split()". This
384 removes the confusing misbehaviour of "qw//" in scalar context, which
385 had inherited that behaviour from split().
386 Thus:
388 $foo = ($bar) = qw(a b c); print "$foo⎪$bar\n";
390 now correctly prints "3⎪a", instead of "2⎪a".
392 Better worst-case behavior of hashes
394 Small changes in the hashing algorithm have been implemented in order
396 to improve the distribution of lower order bits in the hashed value.
397 This is expected to yield better performance on keys that are repeated
398 sequences.
399 pack() format 'Z' supported
401 The new format type 'Z' is useful for packing and unpacking null-termi‐
403 nated strings. See "pack" in perlfunc.
404 pack() format modifier '!' supported
406 The new format type modifier '!' is useful for packing and unpacking
408 native shorts, ints, and longs. See "pack" in perlfunc.
409 pack() and unpack() support counted strings
411 The template character '/' can be used to specify a counted string type
413 to be packed or unpacked. See "pack" in perlfunc.
414 Comments in pack() templates
416 The '#' character in a template introduces a comment up to end of the
418 line. This facilitates documentation of pack() templates.
419 Weak references
421 In previous versions of Perl, you couldn't cache objects so as to allow
423 them to be deleted if the last reference from outside the cache is
424 deleted. The reference in the cache would hold a reference count on
425 the object and the objects would never be destroyed.
426 Another familiar problem is with circular references. When an object
428 references itself, its reference count would never go down to zero, and
429 it would not get destroyed until the program is about to exit.
430 Weak references solve this by allowing you to "weaken" any reference,
432 that is, make it not count towards the reference count. When the last
433 non-weak reference to an object is deleted, the object is destroyed and
434 all the weak references to the object are automatically undef-ed.
435 To use this feature, you need the Devel::WeakRef package from CPAN,
437 which contains additional documentation.
438 NOTE: This is an experimental feature. Details are subject to change.
440 Binary numbers supported
442 Binary numbers are now supported as literals, in s?printf formats, and
444 "oct()":
445 $answer = 0b101010;
447 printf "The answer is: %b\n", oct("0b101010");
448 Lvalue subroutines
450 Subroutines can now return modifiable lvalues. See "Lvalue subrou‐
452 tines" in perlsub.
453 NOTE: This is an experimental feature. Details are subject to change.
455 Some arrows may be omitted in calls through references
457 Perl now allows the arrow to be omitted in many constructs involving
459 subroutine calls through references. For example, "$foo[10]->('foo')"
460 may now be written "$foo[10]('foo')". This is rather similar to how
461 the arrow may be omitted from "$foo[10]->{'foo'}". Note however, that
462 the arrow is still required for "foo(10)->('bar')".
463 Boolean assignment operators are legal lvalues
465 Constructs such as "($a ⎪⎪= 2) += 1" are now allowed.
467 exists() is supported on subroutine names
469 The exists() builtin now works on subroutine names. A subroutine is
471 considered to exist if it has been declared (even if implicitly). See
472 "exists" in perlfunc for examples.
473 exists() and delete() are supported on array elements
475 The exists() and delete() builtins now work on simple arrays as well.
477 The behavior is similar to that on hash elements.
478 exists() can be used to check whether an array element has been ini‐
480 tialized. This avoids autovivifying array elements that don't exist.
481 If the array is tied, the EXISTS() method in the corresponding tied
482 package will be invoked.
483 delete() may be used to remove an element from the array and return it.
485 The array element at that position returns to its uninitialized state,
486 so that testing for the same element with exists() will return false.
487 If the element happens to be the one at the end, the size of the array
488 also shrinks up to the highest element that tests true for exists(), or
489 0 if none such is found. If the array is tied, the DELETE() method in
490 the corresponding tied package will be invoked.
491 See "exists" in perlfunc and "delete" in perlfunc for examples.
493 Pseudo-hashes work better
495 Dereferencing some types of reference values in a pseudo-hash, such as
497 "$ph->{foo}[1]", was accidentally disallowed. This has been corrected.
498 When applied to a pseudo-hash element, exists() now reports whether the
500 specified value exists, not merely if the key is valid.
501 delete() now works on pseudo-hashes. When given a pseudo-hash element
503 or slice it deletes the values corresponding to the keys (but not the
504 keys themselves). See "Pseudo-hashes: Using an array as a hash" in
505 perlref.
506 Pseudo-hash slices with constant keys are now optimized to array
508 lookups at compile-time.
509 List assignments to pseudo-hash slices are now supported.
511 The "fields" pragma now provides ways to create pseudo-hashes, via
513 fields::new() and fields::phash(). See fields.
514 NOTE: The pseudo-hash data type continues to be experimental.
516 Limiting oneself to the interface elements provided by the
517 fields pragma will provide protection from any future changes.
518 Automatic flushing of output buffers
520 fork(), exec(), system(), qx//, and pipe open()s now flush buffers of
522 all files opened for output when the operation was attempted. This
523 mostly eliminates confusing buffering mishaps suffered by users unaware
524 of how Perl internally handles I/O.
525 This is not supported on some platforms like Solaris where a suitably
527 correct implementation of fflush(NULL) isn't available.
528 Better diagnostics on meaningless filehandle operations
530 Constructs such as "open(<FH>)" and "close(<FH>)" are compile time
532 errors. Attempting to read from filehandles that were opened only for
533 writing will now produce warnings (just as writing to read-only file‐
534 handles does).
535 Where possible, buffered data discarded from duped input filehandle
537 "open(NEW, "<&OLD")" now attempts to discard any data that was previ‐
539 ously read and buffered in "OLD" before duping the handle. On plat‐
540 forms where doing this is allowed, the next read operation on "NEW"
541 will return the same data as the corresponding operation on "OLD".
542 Formerly, it would have returned the data from the start of the follow‐
543 ing disk block instead.
544 eof() has the same old magic as <>
546 "eof()" would return true if no attempt to read from "<>" had yet been
548 made. "eof()" has been changed to have a little magic of its own, it
549 now opens the "<>" files.
550 binmode() can be used to set :crlf and :raw modes
552 binmode() now accepts a second argument that specifies a discipline for
554 the handle in question. The two pseudo-disciplines ":raw" and ":crlf"
555 are currently supported on DOS-derivative platforms. See "binmode" in
556 perlfunc and open.
557 "-T" filetest recognizes UTF-8 encoded files as "text"
559 The algorithm used for the "-T" filetest has been enhanced to correctly
561 identify UTF-8 content as "text".
562 system(), backticks and pipe open now reflect exec() failure
564 On Unix and similar platforms, system(), qx() and open(FOO, "cmd ⎪")
566 etc., are implemented via fork() and exec(). When the underlying
567 exec() fails, earlier versions did not report the error properly, since
568 the exec() happened to be in a different process.
569 The child process now communicates with the parent about the error in
571 launching the external command, which allows these constructs to return
572 with their usual error value and set $!.
573 Improved diagnostics
575 Line numbers are no longer suppressed (under most likely circumstances)
577 during the global destruction phase.
578 Diagnostics emitted from code running in threads other than the main
580 thread are now accompanied by the thread ID.
581 Embedded null characters in diagnostics now actually show up. They
583 used to truncate the message in prior versions.
584 $foo::a and $foo::b are now exempt from "possible typo" warnings only
586 if sort() is encountered in package "foo".
587 Unrecognized alphabetic escapes encountered when parsing quote con‐
589 structs now generate a warning, since they may take on new semantics in
590 later versions of Perl.
591 Many diagnostics now report the internal operation in which the warning
593 was provoked, like so:
594 Use of uninitialized value in concatenation (.) at (eval 1) line 1.
596 Use of uninitialized value in print at (eval 1) line 1.
597 Diagnostics that occur within eval may also report the file and line
599 number where the eval is located, in addition to the eval sequence num‐
600 ber and the line number within the evaluated text itself. For example:
601 Not enough arguments for scalar at (eval 4)[newlib/perl5db.pl:1411] line 2, at EOF
603 Diagnostics follow STDERR
605 Diagnostic output now goes to whichever file the "STDERR" handle is
607 pointing at, instead of always going to the underlying C runtime
608 library's "stderr".
609 More consistent close-on-exec behavior
611 On systems that support a close-on-exec flag on filehandles, the flag
613 is now set for any handles created by pipe(), socketpair(), socket(),
614 and accept(), if that is warranted by the value of $^F that may be in
615 effect. Earlier versions neglected to set the flag for handles created
616 with these operators. See "pipe" in perlfunc, "socketpair" in perl‐
617 func, "socket" in perlfunc, "accept" in perlfunc, and "$^F" in perlvar.
618 syswrite() ease-of-use
620 The length argument of "syswrite()" has become optional.
622 Better syntax checks on parenthesized unary operators
624 Expressions such as:
626 print defined(&foo,&bar,&baz);
628 print uc("foo","bar","baz");
629 undef($foo,&bar);
630 used to be accidentally allowed in earlier versions, and produced
632 unpredictable behaviour. Some produced ancillary warnings when used in
633 this way; others silently did the wrong thing.
634 The parenthesized forms of most unary operators that expect a single
636 argument now ensure that they are not called with more than one argu‐
637 ment, making the cases shown above syntax errors. The usual behaviour
638 of:
639 print defined &foo, &bar, &baz;
641 print uc "foo", "bar", "baz";
642 undef $foo, &bar;
643 remains unchanged. See perlop.
645 Bit operators support full native integer width
647 The bit operators (& ⎪ ^ ~ << >>) now operate on the full native inte‐
649 gral width (the exact size of which is available in $Config{ivsize}).
650 For example, if your platform is either natively 64-bit or if Perl has
651 been configured to use 64-bit integers, these operations apply to 8
652 bytes (as opposed to 4 bytes on 32-bit platforms). For portability, be
653 sure to mask off the excess bits in the result of unary "~", e.g., "~$x
654 & 0xffffffff".
655 Improved security features
657 More potentially unsafe operations taint their results for improved
659 security.
660 The "passwd" and "shell" fields returned by the getpwent(), getpwnam(),
662 and getpwuid() are now tainted, because the user can affect their own
663 encrypted password and login shell.
664 The variable modified by shmread(), and messages returned by msgrcv()
666 (and its object-oriented interface IPC::SysV::Msg::rcv) are also
667 tainted, because other untrusted processes can modify messages and
668 shared memory segments for their own nefarious purposes.
669 More functional bareword prototype (*)
671 Bareword prototypes have been rationalized to enable them to be used to
673 override builtins that accept barewords and interpret them in a special
674 way, such as "require" or "do".
675 Arguments prototyped as "*" will now be visible within the subroutine
677 as either a simple scalar or as a reference to a typeglob. See "Proto‐
678 types" in perlsub.
679 "require" and "do" may be overridden
681 "require" and "do 'file'" operations may be overridden locally by
683 importing subroutines of the same name into the current package (or
684 globally by importing them into the CORE::GLOBAL:: namespace). Over‐
685 riding "require" will also affect "use", provided the override is visi‐
686 ble at compile-time. See "Overriding Built-in Functions" in perlsub.
687 $^X variables may now have names longer than one character
689 Formerly, $^X was synonymous with ${"\cX"}, but $^XY was a syntax
691 error. Now variable names that begin with a control character may be
692 arbitrarily long. However, for compatibility reasons, these variables
693 must be written with explicit braces, as "${^XY}" for example.
694 "${^XYZ}" is synonymous with ${"\cXYZ"}. Variable names with more than
695 one control character, such as "${^XY^Z}", are illegal.
696 The old syntax has not changed. As before, `^X' may be either a lit‐
698 eral control-X character or the two-character sequence `caret' plus
699 `X'. When braces are omitted, the variable name stops after the con‐
700 trol character. Thus "$^XYZ" continues to be synonymous with "$^X .
701 "YZ"" as before.
702 As before, lexical variables may not have names beginning with control
704 characters. As before, variables whose names begin with a control
705 character are always forced to be in package `main'. All such vari‐
706 ables are reserved for future extensions, except those that begin with
707 "^_", which may be used by user programs and are guaranteed not to
708 acquire special meaning in any future version of Perl.
709 New variable $^C reflects "-c" switch
711 $^C has a boolean value that reflects whether perl is being run in com‐
713 pile-only mode (i.e. via the "-c" switch). Since BEGIN blocks are exe‐
714 cuted under such conditions, this variable enables perl code to deter‐
715 mine whether actions that make sense only during normal running are
716 warranted. See perlvar.
717 New variable $^V contains Perl version as a string
719 $^V contains the Perl version number as a string composed of characters
721 whose ordinals match the version numbers, i.e. v5.6.0. This may be
722 used in string comparisons.
723 See "Support for strings represented as a vector of ordinals" for an
725 example.
726 Optional Y2K warnings
728 If Perl is built with the cpp macro "PERL_Y2KWARN" defined, it emits
730 optional warnings when concatenating the number 19 with another number.
731 This behavior must be specifically enabled when running Configure. See
733 INSTALL and README.Y2K.
734 Arrays now always interpolate into double-quoted strings
736 In double-quoted strings, arrays now interpolate, no matter what. The
738 behavior in earlier versions of perl 5 was that arrays would interpo‐
739 late into strings if the array had been mentioned before the string was
740 compiled, and otherwise Perl would raise a fatal compile-time error.
741 In versions 5.000 through 5.003, the error was
742 Literal @example now requires backslash
744 In versions 5.004_01 through 5.6.0, the error was
746 In string, @example now must be written as \@example
748 The idea here was to get people into the habit of writing "fred\@exam‐
750 ple.com" when they wanted a literal "@" sign, just as they have always
751 written "Give me back my \$5" when they wanted a literal "$" sign.
752 Starting with 5.6.1, when Perl now sees an "@" sign in a double-quoted
754 string, it always attempts to interpolate an array, regardless of
755 whether or not the array has been used or declared already. The fatal
756 error has been downgraded to an optional warning:
757 Possible unintended interpolation of @example in string
759 This warns you that "fred@example.com" is going to turn into "fred.com"
761 if you don't backslash the "@". See
762 http://www.plover.com/~mjd/perl/at-error.html for more details about
763 the history here.
764 @- and @+ provide starting/ending offsets of regex matches
766 The new magic variables @- and @+ provide the starting and ending off‐
768 sets, respectively, of $&, $1, $2, etc. See perlvar for details.
769
771 Modules
772 attributes
774 While used internally by Perl as a pragma, this module also pro‐
775 vides a way to fetch subroutine and variable attributes. See
776 attributes.
777 B The Perl Compiler suite has been extensively reworked for this
779 release. More of the standard Perl testsuite passes when run under
780 the Compiler, but there is still a significant way to go to achieve
781 production quality compiled executables.
782 NOTE: The Compiler suite remains highly experimental. The
784 generated code may not be correct, even when it manages to execute
785 without errors.
786 Benchmark
788 Overall, Benchmark results exhibit lower average error and better
789 timing accuracy.
790 You can now run tests for n seconds instead of guessing the right
792 number of tests to run: e.g., timethese(-5, ...) will run each code
793 for at least 5 CPU seconds. Zero as the "number of repetitions"
794 means "for at least 3 CPU seconds". The output format has also
795 changed. For example:
796 use Benchmark;$x=3;timethese(-5,{a=>sub{$x*$x},b=>sub{$x**2}})
798 will now output something like this:
800 Benchmark: running a, b, each for at least 5 CPU seconds...
802 a: 5 wallclock secs ( 5.77 usr + 0.00 sys = 5.77 CPU) @ 200551.91/s (n=1156516)
803 b: 4 wallclock secs ( 5.00 usr + 0.02 sys = 5.02 CPU) @ 159605.18/s (n=800686)
804 New features: "each for at least N CPU seconds...", "wallclock
806 secs", and the "@ operations/CPU second (n=operations)".
807 timethese() now returns a reference to a hash of Benchmark objects
809 containing the test results, keyed on the names of the tests.
810 timethis() now returns the iterations field in the Benchmark result
812 object instead of 0.
813 timethese(), timethis(), and the new cmpthese() (see below) can
815 also take a format specifier of 'none' to suppress output.
816 A new function countit() is just like timeit() except that it takes
818 a TIME instead of a COUNT.
819 A new function cmpthese() prints a chart comparing the results of
821 each test returned from a timethese() call. For each possible pair
822 of tests, the percentage speed difference (iters/sec or sec‐
823 onds/iter) is shown.
824 For other details, see Benchmark.
826 ByteLoader
828 The ByteLoader is a dedicated extension to generate and run Perl
829 bytecode. See ByteLoader.
830 constant
832 References can now be used.
833 The new version also allows a leading underscore in constant names,
835 but disallows a double leading underscore (as in "__LINE__"). Some
836 other names are disallowed or warned against, including BEGIN, END,
837 etc. Some names which were forced into main:: used to fail
838 silently in some cases; now they're fatal (outside of main::) and
839 an optional warning (inside of main::). The ability to detect
840 whether a constant had been set with a given name has been added.
841 See constant.
843 charnames
845 This pragma implements the "\N" string escape. See charnames.
846 Data::Dumper
848 A "Maxdepth" setting can be specified to avoid venturing too deeply
849 into deep data structures. See Data::Dumper.
850 The XSUB implementation of Dump() is now automatically called if
852 the "Useqq" setting is not in use.
853 Dumping "qr//" objects works correctly.
855 DB "DB" is an experimental module that exposes a clean abstraction to
857 Perl's debugging API.
858 DB_File
860 DB_File can now be built with Berkeley DB versions 1, 2 or 3. See
861 "ext/DB_File/Changes".
862 Devel::DProf
864 Devel::DProf, a Perl source code profiler has been added. See
865 Devel::DProf and dprofpp.
866 Devel::Peek
868 The Devel::Peek module provides access to the internal representa‐
869 tion of Perl variables and data. It is a data debugging tool for
870 the XS programmer.
871 Dumpvalue
873 The Dumpvalue module provides screen dumps of Perl data.
874 DynaLoader
876 DynaLoader now supports a dl_unload_file() function on platforms
877 that support unloading shared objects using dlclose().
878 Perl can also optionally arrange to unload all extension shared
880 objects loaded by Perl. To enable this, build Perl with the Con‐
881 figure option "-Accflags=-DDL_UNLOAD_ALL_AT_EXIT". (This maybe
882 useful if you are using Apache with mod_perl.)
883 English
885 $PERL_VERSION now stands for $^V (a string value) rather than for
886 $] (a numeric value).
887 Env Env now supports accessing environment variables like PATH as array
889 variables.
890 Fcntl
892 More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for
893 large file (more than 4GB) access (NOTE: the O_LARGEFILE is auto‐
894 matically added to sysopen() flags if large file support has been
895 configured, as is the default), Free/Net/OpenBSD locking behaviour
896 flags F_FLOCK, F_POSIX, Linux F_SHLCK, and O_ACCMODE: the combined
897 mask of O_RDONLY, O_WRONLY, and O_RDWR. The seek()/sysseek() con‐
898 stants SEEK_SET, SEEK_CUR, and SEEK_END are available via the
899 ":seek" tag. The chmod()/stat() S_IF* constants and S_IS* func‐
900 tions are available via the ":mode" tag.
901 File::Compare
903 A compare_text() function has been added, which allows custom com‐
904 parison functions. See File::Compare.
905 File::Find
907 File::Find now works correctly when the wanted() function is either
908 autoloaded or is a symbolic reference.
909 A bug that caused File::Find to lose track of the working directory
911 when pruning top-level directories has been fixed.
912 File::Find now also supports several other options to control its
914 behavior. It can follow symbolic links if the "follow" option is
915 specified. Enabling the "no_chdir" option will make File::Find
916 skip changing the current directory when walking directories. The
917 "untaint" flag can be useful when running with taint checks
918 enabled.
919 See File::Find.
921 File::Glob
923 This extension implements BSD-style file globbing. By default, it
924 will also be used for the internal implementation of the glob()
925 operator. See File::Glob.
926 File::Spec
928 New methods have been added to the File::Spec module: devnull()
929 returns the name of the null device (/dev/null on Unix) and
930 tmpdir() the name of the temp directory (normally /tmp on Unix).
931 There are now also methods to convert between absolute and relative
932 filenames: abs2rel() and rel2abs(). For compatibility with operat‐
933 ing systems that specify volume names in file paths, the split‐
934 path(), splitdir(), and catdir() methods have been added.
935 File::Spec::Functions
937 The new File::Spec::Functions modules provides a function interface
938 to the File::Spec module. Allows shorthand
939 $fullname = catfile($dir1, $dir2, $file);
941 instead of
943 $fullname = File::Spec->catfile($dir1, $dir2, $file);
945 Getopt::Long
947 Getopt::Long licensing has changed to allow the Perl Artistic
948 License as well as the GPL. It used to be GPL only, which got in
949 the way of non-GPL applications that wanted to use Getopt::Long.
950 Getopt::Long encourages the use of Pod::Usage to produce help mes‐
952 sages. For example:
953 use Getopt::Long;
955 use Pod::Usage;
956 my $man = 0;
957 my $help = 0;
958 GetOptions('help⎪?' => \$help, man => \$man) or pod2usage(2);
959 pod2usage(1) if $help;
960 pod2usage(-exitstatus => 0, -verbose => 2) if $man;
961 __END__
963 =head1 NAME
965 sample - Using Getopt::Long and Pod::Usage
967 =head1 SYNOPSIS
969 sample [options] [file ...]
971 Options:
973 -help brief help message
974 -man full documentation
975 =head1 OPTIONS
977 =over 8
979 =item B<-help>
981 Print a brief help message and exits.
983 =item B<-man>
985 Prints the manual page and exits.
987 =back
989 =head1 DESCRIPTION
991 B<This program> will read the given input file(s) and do something
993 useful with the contents thereof.
994 =cut
996 See Pod::Usage for details.
998 A bug that prevented the non-option call-back <> from being speci‐
1000 fied as the first argument has been fixed.
1001 To specify the characters < and > as option starters, use ><. Note,
1003 however, that changing option starters is strongly deprecated.
1004 IO write() and syswrite() will now accept a single-argument form of
1006 the call, for consistency with Perl's syswrite().
1007 You can now create a TCP-based IO::Socket::INET without forcing a
1009 connect attempt. This allows you to configure its options (like
1010 making it non-blocking) and then call connect() manually.
1011 A bug that prevented the IO::Socket::protocol() accessor from ever
1013 returning the correct value has been corrected.
1014 IO::Socket::connect now uses non-blocking IO instead of alarm() to
1016 do connect timeouts.
1017 IO::Socket::accept now uses select() instead of alarm() for doing
1019 timeouts.
1020 IO::Socket::INET->new now sets $! correctly on failure. $@ is still
1022 set for backwards compatibility.
1023 JPL Java Perl Lingo is now distributed with Perl. See jpl/README for
1025 more information.
1026 lib "use lib" now weeds out any trailing duplicate entries. "no lib"
1028 removes all named entries.
1029 Math::BigInt
1031 The bitwise operations "<<", ">>", "&", "⎪", and "~" are now sup‐
1032 ported on bigints.
1033 Math::Complex
1035 The accessor methods Re, Im, arg, abs, rho, and theta can now also
1036 act as mutators (accessor $z->Re(), mutator $z->Re(3)).
1037 The class method "display_format" and the corresponding object
1039 method "display_format", in addition to accepting just one argu‐
1040 ment, now can also accept a parameter hash. Recognized keys of a
1041 parameter hash are "style", which corresponds to the old one param‐
1042 eter case, and two new parameters: "format", which is a
1043 printf()-style format string (defaults usually to "%.15g", you can
1044 revert to the default by setting the format string to "undef") used
1045 for both parts of a complex number, and "polar_pretty_print"
1046 (defaults to true), which controls whether an attempt is made to
1047 try to recognize small multiples and rationals of pi (2pi, pi/2) at
1048 the argument (angle) of a polar complex number.
1049 The potentially disruptive change is that in list context both
1051 methods now return the parameter hash, instead of only the value of
1052 the "style" parameter.
1053 Math::Trig
1055 A little bit of radial trigonometry (cylindrical and spherical),
1056 radial coordinate conversions, and the great circle distance were
1057 added.
1058 Pod::Parser, Pod::InputObjects
1060 Pod::Parser is a base class for parsing and selecting sections of
1061 pod documentation from an input stream. This module takes care of
1062 identifying pod paragraphs and commands in the input and hands off
1063 the parsed paragraphs and commands to user-defined methods which
1064 are free to interpret or translate them as they see fit.
1065 Pod::InputObjects defines some input objects needed by Pod::Parser,
1067 and for advanced users of Pod::Parser that need more about a com‐
1068 mand besides its name and text.
1069 As of release 5.6.0 of Perl, Pod::Parser is now the officially
1071 sanctioned "base parser code" recommended for use by all pod2xxx
1072 translators. Pod::Text (pod2text) and Pod::Man (pod2man) have
1073 already been converted to use Pod::Parser and efforts to convert
1074 Pod::HTML (pod2html) are already underway. For any questions or
1075 comments about pod parsing and translating issues and utilities,
1076 please use the pod-people@perl.org mailing list.
1077 For further information, please see Pod::Parser and Pod::InputOb‐
1079 jects.
1080 Pod::Checker, podchecker
1082 This utility checks pod files for correct syntax, according to
1083 perlpod. Obvious errors are flagged as such, while warnings are
1084 printed for mistakes that can be handled gracefully. The checklist
1085 is not complete yet. See Pod::Checker.
1086 Pod::ParseUtils, Pod::Find
1088 These modules provide a set of gizmos that are useful mainly for
1089 pod translators. Pod::Find traverses directory structures and
1090 returns found pod files, along with their canonical names (like
1091 "File::Spec::Unix"). Pod::ParseUtils contains Pod::List (useful
1092 for storing pod list information), Pod::Hyperlink (for parsing the
1093 contents of "L<>" sequences) and Pod::Cache (for caching informa‐
1094 tion about pod files, e.g., link nodes).
1095 Pod::Select, podselect
1097 Pod::Select is a subclass of Pod::Parser which provides a function
1098 named "podselect()" to filter out user-specified sections of raw
1099 pod documentation from an input stream. podselect is a script that
1100 provides access to Pod::Select from other scripts to be used as a
1101 filter. See Pod::Select.
1102 Pod::Usage, pod2usage
1104 Pod::Usage provides the function "pod2usage()" to print usage mes‐
1105 sages for a Perl script based on its embedded pod documentation.
1106 The pod2usage() function is generally useful to all script authors
1107 since it lets them write and maintain a single source (the pods)
1108 for documentation, thus removing the need to create and maintain
1109 redundant usage message text consisting of information already in
1110 the pods.
1111 There is also a pod2usage script which can be used from other kinds
1113 of scripts to print usage messages from pods (even for non-Perl
1114 scripts with pods embedded in comments).
1115 For details and examples, please see Pod::Usage.
1117 Pod::Text and Pod::Man
1119 Pod::Text has been rewritten to use Pod::Parser. While pod2text()
1120 is still available for backwards compatibility, the module now has
1121 a new preferred interface. See Pod::Text for the details. The new
1122 Pod::Text module is easily subclassed for tweaks to the output, and
1123 two such subclasses (Pod::Text::Termcap for man-page-style bold and
1124 underlining using termcap information, and Pod::Text::Color for
1125 markup with ANSI color sequences) are now standard.
1126 pod2man has been turned into a module, Pod::Man, which also uses
1128 Pod::Parser. In the process, several outstanding bugs related to
1129 quotes in section headers, quoting of code escapes, and nested
1130 lists have been fixed. pod2man is now a wrapper script around this
1131 module.
1132 SDBM_File
1134 An EXISTS method has been added to this module (and sdbm_exists()
1135 has been added to the underlying sdbm library), so one can now call
1136 exists on an SDBM_File tied hash and get the correct result, rather
1137 than a runtime error.
1138 A bug that may have caused data loss when more than one disk block
1140 happens to be read from the database in a single FETCH() has been
1141 fixed.
1142 Sys::Syslog
1144 Sys::Syslog now uses XSUBs to access facilities from syslog.h so it
1145 no longer requires syslog.ph to exist.
1146 Sys::Hostname
1148 Sys::Hostname now uses XSUBs to call the C library's gethostname()
1149 or uname() if they exist.
1150 Term::ANSIColor
1152 Term::ANSIColor is a very simple module to provide easy and read‐
1153 able access to the ANSI color and highlighting escape sequences,
1154 supported by most ANSI terminal emulators. It is now included
1155 standard.
1156 Time::Local
1158 The timelocal() and timegm() functions used to silently return
1159 bogus results when the date fell outside the machine's integer
1160 range. They now consistently croak() if the date falls in an
1161 unsupported range.
1162 Win32
1164 The error return value in list context has been changed for all
1165 functions that return a list of values. Previously these functions
1166 returned a list with a single element "undef" if an error occurred.
1167 Now these functions return the empty list in these situations.
1168 This applies to the following functions:
1169 Win32::FsType
1171 Win32::GetOSVersion
1172 The remaining functions are unchanged and continue to return
1174 "undef" on error even in list context.
1175 The Win32::SetLastError(ERROR) function has been added as a comple‐
1177 ment to the Win32::GetLastError() function.
1178 The new Win32::GetFullPathName(FILENAME) returns the full absolute
1180 pathname for FILENAME in scalar context. In list context it
1181 returns a two-element list containing the fully qualified directory
1182 name and the filename. See Win32.
1183 XSLoader
1185 The XSLoader extension is a simpler alternative to DynaLoader. See
1186 XSLoader.
1187 DBM Filters
1189 A new feature called "DBM Filters" has been added to all the DBM
1190 modules--DB_File, GDBM_File, NDBM_File, ODBM_File, and SDBM_File.
1191 DBM Filters add four new methods to each DBM module:
1192 filter_store_key
1194 filter_store_value
1195 filter_fetch_key
1196 filter_fetch_value
1197 These can be used to filter key-value pairs before the pairs are
1199 written to the database or just after they are read from the data‐
1200 base. See perldbmfilter for further information.
1201 Pragmata
1203 "use attrs" is now obsolete, and is only provided for backward-compati‐
1205 bility. It's been replaced by the "sub : attributes" syntax. See
1206 "Subroutine Attributes" in perlsub and attributes.
1207 Lexical warnings pragma, "use warnings;", to control optional warnings.
1209 See perllexwarn.
1210 "use filetest" to control the behaviour of filetests ("-r" "-w" ...).
1212 Currently only one subpragma implemented, "use filetest 'access';",
1213 that uses access(2) or equivalent to check permissions instead of using
1214 stat(2) as usual. This matters in filesystems where there are ACLs
1215 (access control lists): the stat(2) might lie, but access(2) knows bet‐
1216 ter.
1217 The "open" pragma can be used to specify default disciplines for handle
1219 constructors (e.g. open()) and for qx//. The two pseudo-disciplines
1220 ":raw" and ":crlf" are currently supported on DOS-derivative platforms
1221 (i.e. where binmode is not a no-op). See also "binmode() can be used
1222 to set :crlf and :raw modes".
1223
1225 dprofpp
1226 "dprofpp" is used to display profile data generated using
1228 "Devel::DProf". See dprofpp.
1229 find2perl
1231 The "find2perl" utility now uses the enhanced features of the
1233 File::Find module. The -depth and -follow options are supported. Pod
1234 documentation is also included in the script.
1235 h2xs
1237 The "h2xs" tool can now work in conjunction with "C::Scan" (available
1239 from CPAN) to automatically parse real-life header files. The "-M",
1240 "-a", "-k", and "-o" options are new.
1241 perlcc
1243 "perlcc" now supports the C and Bytecode backends. By default, it gen‐
1245 erates output from the simple C backend rather than the optimized C
1246 backend.
1247 Support for non-Unix platforms has been improved.
1249 perldoc
1251 "perldoc" has been reworked to avoid possible security holes. It will
1253 not by default let itself be run as the superuser, but you may still
1254 use the -U switch to try to make it drop privileges first.
1255 The Perl Debugger
1257 Many bug fixes and enhancements were added to perl5db.pl, the Perl
1259 debugger. The help documentation was rearranged. New commands include
1260 "< ?", "> ?", and "{ ?" to list out current actions, "man docpage" to
1261 run your doc viewer on some perl docset, and support for quoted
1262 options. The help information was rearranged, and should be viewable
1263 once again if you're using less as your pager. A serious security hole
1264 was plugged--you should immediately remove all older versions of the
1265 Perl debugger as installed in previous releases, all the way back to
1266 perl3, from your system to avoid being bitten by this.
1267
1269 Many of the platform-specific README files are now part of the perl
1270 installation. See perl for the complete list.
1271 perlapi.pod
1273 The official list of public Perl API functions.
1274 perlboot.pod
1276 A tutorial for beginners on object-oriented Perl.
1277 perlcompile.pod
1279 An introduction to using the Perl Compiler suite.
1280 perldbmfilter.pod
1282 A howto document on using the DBM filter facility.
1283 perldebug.pod
1285 All material unrelated to running the Perl debugger, plus all low-
1286 level guts-like details that risked crushing the casual user of the
1287 debugger, have been relocated from the old manpage to the next
1288 entry below.
1289 perldebguts.pod
1291 This new manpage contains excessively low-level material not
1292 related to the Perl debugger, but slightly related to debugging
1293 Perl itself. It also contains some arcane internal details of how
1294 the debugging process works that may only be of interest to devel‐
1295 opers of Perl debuggers.
1296 perlfork.pod
1298 Notes on the fork() emulation currently available for the Windows
1299 platform.
1300 perlfilter.pod
1302 An introduction to writing Perl source filters.
1303 perlhack.pod
1305 Some guidelines for hacking the Perl source code.
1306 perlintern.pod
1308 A list of internal functions in the Perl source code. (List is
1309 currently empty.)
1310 perllexwarn.pod
1312 Introduction and reference information about lexically scoped warn‐
1313 ing categories.
1314 perlnumber.pod
1316 Detailed information about numbers as they are represented in Perl.
1317 perlopentut.pod
1319 A tutorial on using open() effectively.
1320 perlreftut.pod
1322 A tutorial that introduces the essentials of references.
1323 perltootc.pod
1325 A tutorial on managing class data for object modules.
1326 perltodo.pod
1328 Discussion of the most often wanted features that may someday be
1329 supported in Perl.
1330 perlunicode.pod
1332 An introduction to Unicode support features in Perl.
1333
1335 Simple sort() using { $a <=> $b } and the like are optimized
1336 Many common sort() operations using a simple inlined block are now
1338 optimized for faster performance.
1339 Optimized assignments to lexical variables
1341 Certain operations in the RHS of assignment statements have been opti‐
1343 mized to directly set the lexical variable on the LHS, eliminating
1344 redundant copying overheads.
1345 Faster subroutine calls
1347 Minor changes in how subroutine calls are handled internally provide
1349 marginal improvements in performance.
1350 delete(), each(), values() and hash iteration are faster
1352 The hash values returned by delete(), each(), values() and hashes in a
1354 list context are the actual values in the hash, instead of copies.
1355 This results in significantly better performance, because it eliminates
1356 needless copying in most situations.
1357
1359 -Dusethreads means something different
1360 The -Dusethreads flag now enables the experimental interpreter-based
1362 thread support by default. To get the flavor of experimental threads
1363 that was in 5.005 instead, you need to run Configure with "-Dusethreads
1364 -Duse5005threads".
1365 As of v5.6.0, interpreter-threads support is still lacking a way to
1367 create new threads from Perl (i.e., "use Thread;" will not work with
1368 interpreter threads). "use Thread;" continues to be available when you
1369 specify the -Duse5005threads option to Configure, bugs and all.
1370 NOTE: Support for threads continues to be an experimental feature.
1372 Interfaces and implementation are subject to sudden and drastic changes.
1373 New Configure flags
1375 The following new flags may be enabled on the Configure command line by
1377 running Configure with "-Dflag".
1378 usemultiplicity
1380 usethreads useithreads (new interpreter threads: no Perl API yet)
1381 usethreads use5005threads (threads as they were in 5.005)
1382 use64bitint (equal to now deprecated 'use64bits')
1384 use64bitall
1385 uselongdouble
1387 usemorebits
1388 uselargefiles
1389 usesocks (only SOCKS v5 supported)
1390 Threadedness and 64-bitness now more daring
1392 The Configure options enabling the use of threads and the use of
1394 64-bitness are now more daring in the sense that they no more have an
1395 explicit list of operating systems of known threads/64-bit capabili‐
1396 ties. In other words: if your operating system has the necessary APIs
1397 and datatypes, you should be able just to go ahead and use them, for
1398 threads by Configure -Dusethreads, and for 64 bits either explicitly by
1399 Configure -Duse64bitint or implicitly if your system has 64-bit wide
1400 datatypes. See also "64-bit support".
1401 Long Doubles
1403 Some platforms have "long doubles", floating point numbers of even
1405 larger range than ordinary "doubles". To enable using long doubles for
1406 Perl's scalars, use -Duselongdouble.
1407 -Dusemorebits
1409 You can enable both -Duse64bitint and -Duselongdouble with -Duse‐
1411 morebits. See also "64-bit support".
1412 -Duselargefiles
1414 Some platforms support system APIs that are capable of handling large
1416 files (typically, files larger than two gigabytes). Perl will try to
1417 use these APIs if you ask for -Duselargefiles.
1418 See "Large file support" for more information.
1420 installusrbinperl
1422 You can use "Configure -Uinstallusrbinperl" which causes installperl to
1424 skip installing perl also as /usr/bin/perl. This is useful if you pre‐
1425 fer not to modify /usr/bin for some reason or another but harmful
1426 because many scripts assume to find Perl in /usr/bin/perl.
1427 SOCKS support
1429 You can use "Configure -Dusesocks" which causes Perl to probe for the
1431 SOCKS proxy protocol library (v5, not v4). For more information on
1432 SOCKS, see:
1433 http://www.socks.nec.com/
1435 "-A" flag
1437 You can "post-edit" the Configure variables using the Configure "-A"
1439 switch. The editing happens immediately after the platform specific
1440 hints files have been processed but before the actual configuration
1441 process starts. Run "Configure -h" to find out the full "-A" syntax.
1442 Enhanced Installation Directories
1444 The installation structure has been enriched to improve the support for
1446 maintaining multiple versions of perl, to provide locations for vendor-
1447 supplied modules, scripts, and manpages, and to ease maintenance of
1448 locally-added modules, scripts, and manpages. See the section on
1449 Installation Directories in the INSTALL file for complete details. For
1450 most users building and installing from source, the defaults should be
1451 fine.
1452 If you previously used "Configure -Dsitelib" or "-Dsitearch" to set
1454 special values for library directories, you might wish to consider
1455 using the new "-Dsiteprefix" setting instead. Also, if you wish to re-
1456 use a config.sh file from an earlier version of perl, you should be
1457 sure to check that Configure makes sensible choices for the new direc‐
1458 tories. See INSTALL for complete details.
1459
1461 Supported platforms
1462 · The Mach CThreads (NEXTSTEP, OPENSTEP) are now supported by the
1464 Thread extension.
1465 · GNU/Hurd is now supported.
1467 · Rhapsody/Darwin is now supported.
1469 · EPOC is now supported (on Psion 5).
1471 · The cygwin port (formerly cygwin32) has been greatly improved.
1473 DOS
1475 · Perl now works with djgpp 2.02 (and 2.03 alpha).
1477 · Environment variable names are not converted to uppercase any more.
1479 · Incorrect exit codes from backticks have been fixed.
1481 · This port continues to use its own builtin globbing (not
1483 File::Glob).
1484 OS390 (OpenEdition MVS)
1486 Support for this EBCDIC platform has not been renewed in this release.
1488 There are difficulties in reconciling Perl's standardization on UTF-8
1489 as its internal representation for characters with the EBCDIC character
1490 set, because the two are incompatible.
1491 It is unclear whether future versions will renew support for this plat‐
1493 form, but the possibility exists.
1494 VMS
1496 Numerous revisions and extensions to configuration, build, testing, and
1498 installation process to accommodate core changes and VMS-specific
1499 options.
1500 Expand %ENV-handling code to allow runtime mapping to logical names,
1502 CLI symbols, and CRTL environ array.
1503 Extension of subprocess invocation code to accept filespecs as command
1505 "verbs".
1506 Add to Perl command line processing the ability to use default file
1508 types and to recognize Unix-style "2>&1".
1509 Expansion of File::Spec::VMS routines, and integration into ExtU‐
1511 tils::MM_VMS.
1512 Extension of ExtUtils::MM_VMS to handle complex extensions more flexi‐
1514 bly.
1515 Barewords at start of Unix-syntax paths may be treated as text rather
1517 than only as logical names.
1518 Optional secure translation of several logical names used internally by
1520 Perl.
1521 Miscellaneous bugfixing and porting of new core code to VMS.
1523 Thanks are gladly extended to the many people who have contributed VMS
1525 patches, testing, and ideas.
1526 Win32
1528 Perl can now emulate fork() internally, using multiple interpreters
1530 running in different concurrent threads. This support must be enabled
1531 at build time. See perlfork for detailed information.
1532 When given a pathname that consists only of a drivename, such as "A:",
1534 opendir() and stat() now use the current working directory for the
1535 drive rather than the drive root.
1536 The builtin XSUB functions in the Win32:: namespace are documented.
1538 See Win32.
1539 $^X now contains the full path name of the running executable.
1541 A Win32::GetLongPathName() function is provided to complement
1543 Win32::GetFullPathName() and Win32::GetShortPathName(). See Win32.
1544 POSIX::uname() is supported.
1546 system(1,...) now returns true process IDs rather than process handles.
1548 kill() accepts any real process id, rather than strictly return values
1549 from system(1,...).
1550 For better compatibility with Unix, "kill(0, $pid)" can now be used to
1552 test whether a process exists.
1553 The "Shell" module is supported.
1555 Better support for building Perl under command.com in Windows 95 has
1557 been added.
1558 Scripts are read in binary mode by default to allow ByteLoader (and the
1560 filter mechanism in general) to work properly. For compatibility, the
1561 DATA filehandle will be set to text mode if a carriage return is
1562 detected at the end of the line containing the __END__ or __DATA__
1563 token; if not, the DATA filehandle will be left open in binary mode.
1564 Earlier versions always opened the DATA filehandle in text mode.
1565 The glob() operator is implemented via the "File::Glob" extension,
1567 which supports glob syntax of the C shell. This increases the flexi‐
1568 bility of the glob() operator, but there may be compatibility issues
1569 for programs that relied on the older globbing syntax. If you want to
1570 preserve compatibility with the older syntax, you might want to run
1571 perl with "-MFile::DosGlob". For details and compatibility informa‐
1572 tion, see File::Glob.
1573
1575 <HANDLE> on empty files
1576 With $/ set to "undef", "slurping" an empty file returns a string of
1578 zero length (instead of "undef", as it used to) the first time the HAN‐
1579 DLE is read after $/ is set to "undef". Further reads yield "undef".
1580 This means that the following will append "foo" to an empty file (it
1582 used to do nothing):
1583 perl -0777 -pi -e 's/^/foo/' empty_file
1585 The behaviour of:
1587 perl -pi -e 's/^/foo/' empty_file
1589 is unchanged (it continues to leave the file empty).
1591 "eval '...'" improvements
1593 Line numbers (as reflected by caller() and most diagnostics) within
1595 "eval '...'" were often incorrect where here documents were involved.
1596 This has been corrected.
1597 Lexical lookups for variables appearing in "eval '...'" within func‐
1599 tions that were themselves called within an "eval '...'" were searching
1600 the wrong place for lexicals. The lexical search now correctly ends at
1601 the subroutine's block boundary.
1602 The use of "return" within "eval {...}" caused $@ not to be reset cor‐
1604 rectly when no exception occurred within the eval. This has been
1605 fixed.
1606 Parsing of here documents used to be flawed when they appeared as the
1608 replacement expression in "eval 's/.../.../e'". This has been fixed.
1609 All compilation errors are true errors
1611 Some "errors" encountered at compile time were by necessity generated
1613 as warnings followed by eventual termination of the program. This
1614 enabled more such errors to be reported in a single run, rather than
1615 causing a hard stop at the first error that was encountered.
1616 The mechanism for reporting such errors has been reimplemented to queue
1618 compile-time errors and report them at the end of the compilation as
1619 true errors rather than as warnings. This fixes cases where error mes‐
1620 sages leaked through in the form of warnings when code was compiled at
1621 run time using "eval STRING", and also allows such errors to be reli‐
1622 ably trapped using "eval "..."".
1623 Implicitly closed filehandles are safer
1625 Sometimes implicitly closed filehandles (as when they are localized,
1627 and Perl automatically closes them on exiting the scope) could inadver‐
1628 tently set $? or $!. This has been corrected.
1629 Behavior of list slices is more consistent
1631 When taking a slice of a literal list (as opposed to a slice of an
1633 array or hash), Perl used to return an empty list if the result hap‐
1634 pened to be composed of all undef values.
1635 The new behavior is to produce an empty list if (and only if) the orig‐
1637 inal list was empty. Consider the following example:
1638 @a = (1,undef,undef,2)[2,1,2];
1640 The old behavior would have resulted in @a having no elements. The new
1642 behavior ensures it has three undefined elements.
1643 Note in particular that the behavior of slices of the following cases
1645 remains unchanged:
1646 @a = ()[1,2];
1648 @a = (getpwent)[7,0];
1649 @a = (anything_returning_empty_list())[2,1,2];
1650 @a = @b[2,1,2];
1651 @a = @c{'a','b','c'};
1652 See perldata.
1654 "(\$)" prototype and $foo{a}
1656 A scalar reference prototype now correctly allows a hash or array ele‐
1658 ment in that slot.
1659 "goto &sub" and AUTOLOAD
1661 The "goto &sub" construct works correctly when &sub happens to be
1663 autoloaded.
1664 "-bareword" allowed under "use integer"
1666 The autoquoting of barewords preceded by "-" did not work in prior ver‐
1668 sions when the "integer" pragma was enabled. This has been fixed.
1669 Failures in DESTROY()
1671 When code in a destructor threw an exception, it went unnoticed in ear‐
1673 lier versions of Perl, unless someone happened to be looking in $@ just
1674 after the point the destructor happened to run. Such failures are now
1675 visible as warnings when warnings are enabled.
1676 Locale bugs fixed
1678 printf() and sprintf() previously reset the numeric locale back to the
1680 default "C" locale. This has been fixed.
1681 Numbers formatted according to the local numeric locale (such as using
1683 a decimal comma instead of a decimal dot) caused "isn't numeric" warn‐
1684 ings, even while the operations accessing those numbers produced cor‐
1685 rect results. These warnings have been discontinued.
1686 Memory leaks
1688 The "eval 'return sub {...}'" construct could sometimes leak memory.
1690 This has been fixed.
1691 Operations that aren't filehandle constructors used to leak memory when
1693 used on invalid filehandles. This has been fixed.
1694 Constructs that modified @_ could fail to deallocate values in @_ and
1696 thus leak memory. This has been corrected.
1697 Spurious subroutine stubs after failed subroutine calls
1699 Perl could sometimes create empty subroutine stubs when a subroutine
1701 was not found in the package. Such cases stopped later method lookups
1702 from progressing into base packages. This has been corrected.
1703 Taint failures under "-U"
1705 When running in unsafe mode, taint violations could sometimes cause
1707 silent failures. This has been fixed.
1708 END blocks and the "-c" switch
1710 Prior versions used to run BEGIN and END blocks when Perl was run in
1712 compile-only mode. Since this is typically not the expected behavior,
1713 END blocks are not executed anymore when the "-c" switch is used, or if
1714 compilation fails.
1715 See "Support for CHECK blocks" for how to run things when the compile
1717 phase ends.
1718 Potential to leak DATA filehandles
1720 Using the "__DATA__" token creates an implicit filehandle to the file
1722 that contains the token. It is the program's responsibility to close
1723 it when it is done reading from it.
1724 This caveat is now better explained in the documentation. See perl‐
1726 data.
1727
1729 "%s" variable %s masks earlier declaration in same %s
1730 (W misc) A "my" or "our" variable has been redeclared in the cur‐
1731 rent scope or statement, effectively eliminating all access to the
1732 previous instance. This is almost always a typographical error.
1733 Note that the earlier variable will still exist until the end of
1734 the scope or until all closure referents to it are destroyed.
1735 "my sub" not yet implemented
1737 (F) Lexically scoped subroutines are not yet implemented. Don't
1738 try that yet.
1739 "our" variable %s redeclared
1741 (W misc) You seem to have already declared the same global once
1742 before in the current lexical scope.
1743 '!' allowed only after types %s
1745 (F) The '!' is allowed in pack() and unpack() only after certain
1746 types. See "pack" in perlfunc.
1747 / cannot take a count
1749 (F) You had an unpack template indicating a counted-length string,
1750 but you have also specified an explicit size for the string. See
1751 "pack" in perlfunc.
1752 / must be followed by a, A or Z
1754 (F) You had an unpack template indicating a counted-length string,
1755 which must be followed by one of the letters a, A or Z to indicate
1756 what sort of string is to be unpacked. See "pack" in perlfunc.
1757 / must be followed by a*, A* or Z*
1759 (F) You had a pack template indicating a counted-length string,
1760 Currently the only things that can have their length counted are
1761 a*, A* or Z*. See "pack" in perlfunc.
1762 / must follow a numeric type
1764 (F) You had an unpack template that contained a '#', but this did
1765 not follow some numeric unpack specification. See "pack" in perl‐
1766 func.
1767 /%s/: Unrecognized escape \\%c passed through
1769 (W regexp) You used a backslash-character combination which is not
1770 recognized by Perl. This combination appears in an interpolated
1771 variable or a "'"-delimited regular expression. The character was
1772 understood literally.
1773 /%s/: Unrecognized escape \\%c in character class passed through
1775 (W regexp) You used a backslash-character combination which is not
1776 recognized by Perl inside character classes. The character was
1777 understood literally.
1778 /%s/ should probably be written as "%s"
1780 (W syntax) You have used a pattern where Perl expected to find a
1781 string, as in the first argument to "join". Perl will treat the
1782 true or false result of matching the pattern against $_ as the
1783 string, which is probably not what you had in mind.
1784 %s() called too early to check prototype
1786 (W prototype) You've called a function that has a prototype before
1787 the parser saw a definition or declaration for it, and Perl could
1788 not check that the call conforms to the prototype. You need to
1789 either add an early prototype declaration for the subroutine in
1790 question, or move the subroutine definition ahead of the call to
1791 get proper prototype checking. Alternatively, if you are certain
1792 that you're calling the function correctly, you may put an amper‐
1793 sand before the name to avoid the warning. See perlsub.
1794 %s argument is not a HASH or ARRAY element
1796 (F) The argument to exists() must be a hash or array element, such
1797 as:
1798 $foo{$bar}
1800 $ref->{"susie"}[12]
1801 %s argument is not a HASH or ARRAY element or slice
1803 (F) The argument to delete() must be either a hash or array ele‐
1804 ment, such as:
1805 $foo{$bar}
1807 $ref->{"susie"}[12]
1808 or a hash or array slice, such as:
1810 @foo[$bar, $baz, $xyzzy]
1812 @{$ref->[12]}{"susie", "queue"}
1813 %s argument is not a subroutine name
1815 (F) The argument to exists() for "exists &sub" must be a subroutine
1816 name, and not a subroutine call. "exists &sub()" will generate
1817 this error.
1818 %s package attribute may clash with future reserved word: %s
1820 (W reserved) A lowercase attribute name was used that had a pack‐
1821 age-specific handler. That name might have a meaning to Perl
1822 itself some day, even though it doesn't yet. Perhaps you should
1823 use a mixed-case attribute name, instead. See attributes.
1824 (in cleanup) %s
1826 (W misc) This prefix usually indicates that a DESTROY() method
1827 raised the indicated exception. Since destructors are usually
1828 called by the system at arbitrary points during execution, and
1829 often a vast number of times, the warning is issued only once for
1830 any number of failures that would otherwise result in the same mes‐
1831 sage being repeated.
1832 Failure of user callbacks dispatched using the "G_KEEPERR" flag
1834 could also result in this warning. See "G_KEEPERR" in perlcall.
1835 <> should be quotes
1837 (F) You wrote "require <file>" when you should have written
1838 "require 'file'".
1839 Attempt to join self
1841 (F) You tried to join a thread from within itself, which is an
1842 impossible task. You may be joining the wrong thread, or you may
1843 need to move the join() to some other thread.
1844 Bad evalled substitution pattern
1846 (F) You've used the /e switch to evaluate the replacement for a
1847 substitution, but perl found a syntax error in the code to evalu‐
1848 ate, most likely an unexpected right brace '}'.
1849 Bad realloc() ignored
1851 (S) An internal routine called realloc() on something that had
1852 never been malloc()ed in the first place. Mandatory, but can be
1853 disabled by setting environment variable "PERL_BADFREE" to 1.
1854 Bareword found in conditional
1856 (W bareword) The compiler found a bareword where it expected a con‐
1857 ditional, which often indicates that an ⎪⎪ or && was parsed as part
1858 of the last argument of the previous construct, for example:
1859 open FOO ⎪⎪ die;
1861 It may also indicate a misspelled constant that has been inter‐
1863 preted as a bareword:
1864 use constant TYPO => 1;
1866 if (TYOP) { print "foo" }
1867 The "strict" pragma is useful in avoiding such errors.
1869 Binary number > 0b11111111111111111111111111111111 non-portable
1871 (W portable) The binary number you specified is larger than 2**32-1
1872 (4294967295) and therefore non-portable between systems. See perl‐
1873 port for more on portability concerns.
1874 Bit vector size > 32 non-portable
1876 (W portable) Using bit vector sizes larger than 32 is non-portable.
1877 Buffer overflow in prime_env_iter: %s
1879 (W internal) A warning peculiar to VMS. While Perl was preparing
1880 to iterate over %ENV, it encountered a logical name or symbol defi‐
1881 nition which was too long, so it was truncated to the string shown.
1882 Can't check filesystem of script "%s"
1884 (P) For some reason you can't check the filesystem of the script
1885 for nosuid.
1886 Can't declare class for non-scalar %s in "%s"
1888 (S) Currently, only scalar variables can declared with a specific
1889 class qualifier in a "my" or "our" declaration. The semantics may
1890 be extended for other types of variables in future.
1891 Can't declare %s in "%s"
1893 (F) Only scalar, array, and hash variables may be declared as "my"
1894 or "our" variables. They must have ordinary identifiers as names.
1895 Can't ignore signal CHLD, forcing to default
1897 (W signal) Perl has detected that it is being run with the SIGCHLD
1898 signal (sometimes known as SIGCLD) disabled. Since disabling this
1899 signal will interfere with proper determination of exit status of
1900 child processes, Perl has reset the signal to its default value.
1901 This situation typically indicates that the parent program under
1902 which Perl may be running (e.g., cron) is being very careless.
1903 Can't modify non-lvalue subroutine call
1905 (F) Subroutines meant to be used in lvalue context should be
1906 declared as such, see "Lvalue subroutines" in perlsub.
1907 Can't read CRTL environ
1909 (S) A warning peculiar to VMS. Perl tried to read an element of
1910 %ENV from the CRTL's internal environment array and discovered the
1911 array was missing. You need to figure out where your CRTL mis‐
1912 placed its environ or define PERL_ENV_TABLES (see perlvms) so that
1913 environ is not searched.
1914 Can't remove %s: %s, skipping file
1916 (S) You requested an inplace edit without creating a backup file.
1917 Perl was unable to remove the original file to replace it with the
1918 modified file. The file was left unmodified.
1919 Can't return %s from lvalue subroutine
1921 (F) Perl detected an attempt to return illegal lvalues (such as
1922 temporary or readonly values) from a subroutine used as an lvalue.
1923 This is not allowed.
1924 Can't weaken a nonreference
1926 (F) You attempted to weaken something that was not a reference.
1927 Only references can be weakened.
1928 Character class [:%s:] unknown
1930 (F) The class in the character class [: :] syntax is unknown. See
1931 perlre.
1932 Character class syntax [%s] belongs inside character classes
1934 (W unsafe) The character class constructs [: :], [= =], and [. .]
1935 go inside character classes, the [] are part of the construct, for
1936 example: /[012[:alpha:]345]/. Note that [= =] and [. .] are not
1937 currently implemented; they are simply placeholders for future
1938 extensions.
1939 Constant is not %s reference
1941 (F) A constant value (perhaps declared using the "use constant"
1942 pragma) is being dereferenced, but it amounts to the wrong type of
1943 reference. The message indicates the type of reference that was
1944 expected. This usually indicates a syntax error in dereferencing
1945 the constant value. See "Constant Functions" in perlsub and con‐
1946 stant.
1947 constant(%s): %s
1949 (F) The parser found inconsistencies either while attempting to
1950 define an overloaded constant, or when trying to find the character
1951 name specified in the "\N{...}" escape. Perhaps you forgot to load
1952 the corresponding "overload" or "charnames" pragma? See charnames
1953 and overload.
1954 CORE::%s is not a keyword
1956 (F) The CORE:: namespace is reserved for Perl keywords.
1957 defined(@array) is deprecated
1959 (D) defined() is not usually useful on arrays because it checks for
1960 an undefined scalar value. If you want to see if the array is
1961 empty, just use "if (@array) { # not empty }" for example.
1962 defined(%hash) is deprecated
1964 (D) defined() is not usually useful on hashes because it checks for
1965 an undefined scalar value. If you want to see if the hash is
1966 empty, just use "if (%hash) { # not empty }" for example.
1967 Did not produce a valid header
1969 See Server error.
1970 (Did you mean "local" instead of "our"?)
1972 (W misc) Remember that "our" does not localize the declared global
1973 variable. You have declared it again in the same lexical scope,
1974 which seems superfluous.
1975 Document contains no data
1977 See Server error.
1978 entering effective %s failed
1980 (F) While under the "use filetest" pragma, switching the real and
1981 effective uids or gids failed.
1982 false [] range "%s" in regexp
1984 (W regexp) A character class range must start and end at a literal
1985 character, not another character class like "\d" or "[:alpha:]".
1986 The "-" in your false range is interpreted as a literal "-". Con‐
1987 sider quoting the "-", "\-". See perlre.
1988 Filehandle %s opened only for output
1990 (W io) You tried to read from a filehandle opened only for writing.
1991 If you intended it to be a read/write filehandle, you needed to
1992 open it with "+<" or "+>" or "+>>" instead of with "<" or nothing.
1993 If you intended only to read from the file, use "<". See "open" in
1994 perlfunc.
1995 flock() on closed filehandle %s
1997 (W closed) The filehandle you're attempting to flock() got itself
1998 closed some time before now. Check your logic flow. flock() oper‐
1999 ates on filehandles. Are you attempting to call flock() on a
2000 dirhandle by the same name?
2001 Global symbol "%s" requires explicit package name
2003 (F) You've said "use strict vars", which indicates that all vari‐
2004 ables must either be lexically scoped (using "my"), declared
2005 beforehand using "our", or explicitly qualified to say which pack‐
2006 age the global variable is in (using "::").
2007 Hexadecimal number > 0xffffffff non-portable
2009 (W portable) The hexadecimal number you specified is larger than
2010 2**32-1 (4294967295) and therefore non-portable between systems.
2011 See perlport for more on portability concerns.
2012 Ill-formed CRTL environ value "%s"
2014 (W internal) A warning peculiar to VMS. Perl tried to read the
2015 CRTL's internal environ array, and encountered an element without
2016 the "=" delimiter used to separate keys from values. The element
2017 is ignored.
2018 Ill-formed message in prime_env_iter: ⎪%s⎪
2020 (W internal) A warning peculiar to VMS. Perl tried to read a logi‐
2021 cal name or CLI symbol definition when preparing to iterate over
2022 %ENV, and didn't see the expected delimiter between key and value,
2023 so the line was ignored.
2024 Illegal binary digit %s
2026 (F) You used a digit other than 0 or 1 in a binary number.
2027 Illegal binary digit %s ignored
2029 (W digit) You may have tried to use a digit other than 0 or 1 in a
2030 binary number. Interpretation of the binary number stopped before
2031 the offending digit.
2032 Illegal number of bits in vec
2034 (F) The number of bits in vec() (the third argument) must be a
2035 power of two from 1 to 32 (or 64, if your platform supports that).
2036 Integer overflow in %s number
2038 (W overflow) The hexadecimal, octal or binary number you have spec‐
2039 ified either as a literal or as an argument to hex() or oct() is
2040 too big for your architecture, and has been converted to a floating
2041 point number. On a 32-bit architecture the largest hexadecimal,
2042 octal or binary number representable without overflow is
2043 0xFFFFFFFF, 037777777777, or 0b11111111111111111111111111111111
2044 respectively. Note that Perl transparently promotes all numbers to
2045 a floating point representation internally--subject to loss of pre‐
2046 cision errors in subsequent operations.
2047 Invalid %s attribute: %s
2049 The indicated attribute for a subroutine or variable was not recog‐
2050 nized by Perl or by a user-supplied handler. See attributes.
2051 Invalid %s attributes: %s
2053 The indicated attributes for a subroutine or variable were not rec‐
2054 ognized by Perl or by a user-supplied handler. See attributes.
2055 invalid [] range "%s" in regexp
2057 The offending range is now explicitly displayed.
2058 Invalid separator character %s in attribute list
2060 (F) Something other than a colon or whitespace was seen between the
2061 elements of an attribute list. If the previous attribute had a
2062 parenthesised parameter list, perhaps that list was terminated too
2063 soon. See attributes.
2064 Invalid separator character %s in subroutine attribute list
2066 (F) Something other than a colon or whitespace was seen between the
2067 elements of a subroutine attribute list. If the previous attribute
2068 had a parenthesised parameter list, perhaps that list was termi‐
2069 nated too soon.
2070 leaving effective %s failed
2072 (F) While under the "use filetest" pragma, switching the real and
2073 effective uids or gids failed.
2074 Lvalue subs returning %s not implemented yet
2076 (F) Due to limitations in the current implementation, array and
2077 hash values cannot be returned in subroutines used in lvalue con‐
2078 text. See "Lvalue subroutines" in perlsub.
2079 Method %s not permitted
2081 See Server error.
2082 Missing %sbrace%s on \N{}
2084 (F) Wrong syntax of character name literal "\N{charname}" within
2085 double-quotish context.
2086 Missing command in piped open
2088 (W pipe) You used the "open(FH, "⎪ command")" or "open(FH, "command
2089 ⎪")" construction, but the command was missing or blank.
2090 Missing name in "my sub"
2092 (F) The reserved syntax for lexically scoped subroutines requires
2093 that they have a name with which they can be found.
2094 No %s specified for -%c
2096 (F) The indicated command line switch needs a mandatory argument,
2097 but you haven't specified one.
2098 No package name allowed for variable %s in "our"
2100 (F) Fully qualified variable names are not allowed in "our" decla‐
2101 rations, because that doesn't make much sense under existing seman‐
2102 tics. Such syntax is reserved for future extensions.
2103 No space allowed after -%c
2105 (F) The argument to the indicated command line switch must follow
2106 immediately after the switch, without intervening spaces.
2107 no UTC offset information; assuming local time is UTC
2109 (S) A warning peculiar to VMS. Perl was unable to find the local
2110 timezone offset, so it's assuming that local system time is equiva‐
2111 lent to UTC. If it's not, define the logical name SYS$TIME‐
2112 ZONE_DIFFERENTIAL to translate to the number of seconds which need
2113 to be added to UTC to get local time.
2114 Octal number > 037777777777 non-portable
2116 (W portable) The octal number you specified is larger than 2**32-1
2117 (4294967295) and therefore non-portable between systems. See perl‐
2118 port for more on portability concerns.
2119 See also perlport for writing portable code.
2121 panic: del_backref
2123 (P) Failed an internal consistency check while trying to reset a
2124 weak reference.
2125 panic: kid popen errno read
2127 (F) forked child returned an incomprehensible message about its
2128 errno.
2129 panic: magic_killbackrefs
2131 (P) Failed an internal consistency check while trying to reset all
2132 weak references to an object.
2133 Parentheses missing around "%s" list
2135 (W parenthesis) You said something like
2136 my $foo, $bar = @_;
2138 when you meant
2140 my ($foo, $bar) = @_;
2142 Remember that "my", "our", and "local" bind tighter than comma.
2144 Possible unintended interpolation of %s in string
2146 (W ambiguous) It used to be that Perl would try to guess whether
2147 you wanted an array interpolated or a literal @. It no longer does
2148 this; arrays are now always interpolated into strings. This means
2149 that if you try something like:
2150 print "fred@example.com";
2152 and the array @example doesn't exist, Perl is going to print
2154 "fred.com", which is probably not what you wanted. To get a lit‐
2155 eral "@" sign in a string, put a backslash before it, just as you
2156 would to get a literal "$" sign.
2157 Possible Y2K bug: %s
2159 (W y2k) You are concatenating the number 19 with another number,
2160 which could be a potential Year 2000 problem.
2161 pragma "attrs" is deprecated, use "sub NAME : ATTRS" instead
2163 (W deprecated) You have written something like this:
2164 sub doit
2166 {
2167 use attrs qw(locked);
2168 }
2169 You should use the new declaration syntax instead.
2171 sub doit : locked
2173 {
2174 ...
2175 The "use attrs" pragma is now obsolete, and is only provided for
2177 backward-compatibility. See "Subroutine Attributes" in perlsub.
2178 Premature end of script headers
2180 See Server error.
2181 Repeat count in pack overflows
2183 (F) You can't specify a repeat count so large that it overflows
2184 your signed integers. See "pack" in perlfunc.
2185 Repeat count in unpack overflows
2187 (F) You can't specify a repeat count so large that it overflows
2188 your signed integers. See "unpack" in perlfunc.
2189 realloc() of freed memory ignored
2191 (S) An internal routine called realloc() on something that had
2192 already been freed.
2193 Reference is already weak
2195 (W misc) You have attempted to weaken a reference that is already
2196 weak. Doing so has no effect.
2197 setpgrp can't take arguments
2199 (F) Your system has the setpgrp() from BSD 4.2, which takes no
2200 arguments, unlike POSIX setpgid(), which takes a process ID and
2201 process group ID.
2202 Strange *+?{} on zero-length expression
2204 (W regexp) You applied a regular expression quantifier in a place
2205 where it makes no sense, such as on a zero-width assertion. Try
2206 putting the quantifier inside the assertion instead. For example,
2207 the way to match "abc" provided that it is followed by three repe‐
2208 titions of "xyz" is "/abc(?=(?:xyz){3})/", not "/abc(?=xyz){3}/".
2209 switching effective %s is not implemented
2211 (F) While under the "use filetest" pragma, we cannot switch the
2212 real and effective uids or gids.
2213 This Perl can't reset CRTL environ elements (%s)
2215 This Perl can't set CRTL environ elements (%s=%s)
2216 (W internal) Warnings peculiar to VMS. You tried to change or
2217 delete an element of the CRTL's internal environ array, but your
2218 copy of Perl wasn't built with a CRTL that contained the setenv()
2219 function. You'll need to rebuild Perl with a CRTL that does, or
2220 redefine PERL_ENV_TABLES (see perlvms) so that the environ array
2221 isn't the target of the change to %ENV which produced the warning.
2222 Too late to run %s block
2224 (W void) A CHECK or INIT block is being defined during run time
2225 proper, when the opportunity to run them has already passed. Per‐
2226 haps you are loading a file with "require" or "do" when you should
2227 be using "use" instead. Or perhaps you should put the "require" or
2228 "do" inside a BEGIN block.
2229 Unknown open() mode '%s'
2231 (F) The second argument of 3-argument open() is not among the list
2232 of valid modes: "<", ">", ">>", "+<", "+>", "+>>", "-⎪", "⎪-".
2233 Unknown process %x sent message to prime_env_iter: %s
2235 (P) An error peculiar to VMS. Perl was reading values for %ENV
2236 before iterating over it, and someone else stuck a message in the
2237 stream of data Perl expected. Someone's very confused, or perhaps
2238 trying to subvert Perl's population of %ENV for nefarious purposes.
2239 Unrecognized escape \\%c passed through
2241 (W misc) You used a backslash-character combination which is not
2242 recognized by Perl. The character was understood literally.
2243 Unterminated attribute parameter in attribute list
2245 (F) The lexer saw an opening (left) parenthesis character while
2246 parsing an attribute list, but the matching closing (right) paren‐
2247 thesis character was not found. You may need to add (or remove) a
2248 backslash character to get your parentheses to balance. See
2249 attributes.
2250 Unterminated attribute list
2252 (F) The lexer found something other than a simple identifier at the
2253 start of an attribute, and it wasn't a semicolon or the start of a
2254 block. Perhaps you terminated the parameter list of the previous
2255 attribute too soon. See attributes.
2256 Unterminated attribute parameter in subroutine attribute list
2258 (F) The lexer saw an opening (left) parenthesis character while
2259 parsing a subroutine attribute list, but the matching closing
2260 (right) parenthesis character was not found. You may need to add
2261 (or remove) a backslash character to get your parentheses to bal‐
2262 ance.
2263 Unterminated subroutine attribute list
2265 (F) The lexer found something other than a simple identifier at the
2266 start of a subroutine attribute, and it wasn't a semicolon or the
2267 start of a block. Perhaps you terminated the parameter list of the
2268 previous attribute too soon.
2269 Value of CLI symbol "%s" too long
2271 (W misc) A warning peculiar to VMS. Perl tried to read the value
2272 of an %ENV element from a CLI symbol table, and found a resultant
2273 string longer than 1024 characters. The return value has been
2274 truncated to 1024 characters.
2275 Version number must be a constant number
2277 (P) The attempt to translate a "use Module n.n LIST" statement into
2278 its equivalent "BEGIN" block found an internal inconsistency with
2279 the version number.
2280
2282 lib/attrs
2283 Compatibility tests for "sub : attrs" vs the older "use attrs".
2284 lib/env
2286 Tests for new environment scalar capability (e.g., "use Env
2287 qw($BAR);").
2288 lib/env-array
2290 Tests for new environment array capability (e.g., "use Env
2291 qw(@PATH);").
2292 lib/io_const
2294 IO constants (SEEK_*, _IO*).
2295 lib/io_dir
2297 Directory-related IO methods (new, read, close, rewind, tied
2298 delete).
2299 lib/io_multihomed
2301 INET sockets with multi-homed hosts.
2302 lib/io_poll
2304 IO poll().
2305 lib/io_unix
2307 UNIX sockets.
2308 op/attrs
2310 Regression tests for "my ($x,@y,%z) : attrs" and <sub : attrs>.
2311 op/filetest
2313 File test operators.
2314 op/lex_assign
2316 Verify operations that access pad objects (lexicals and tempo‐
2317 raries).
2318 op/exists_sub
2320 Verify "exists &sub" operations.
2321
2323 Perl Source Incompatibilities
2324 Beware that any new warnings that have been added or old ones that have
2326 been enhanced are not considered incompatible changes.
2327 Since all new warnings must be explicitly requested via the "-w" switch
2329 or the "warnings" pragma, it is ultimately the programmer's responsi‐
2330 bility to ensure that warnings are enabled judiciously.
2331 CHECK is a new keyword
2333 All subroutine definitions named CHECK are now special. See
2334 "/"Support for CHECK blocks"" for more information.
2335 Treatment of list slices of undef has changed
2337 There is a potential incompatibility in the behavior of list slices
2338 that are comprised entirely of undefined values. See "Behavior of
2339 list slices is more consistent".
2340 Format of $English::PERL_VERSION is different
2342 The English module now sets $PERL_VERSION to $^V (a string value)
2343 rather than $] (a numeric value). This is a potential incompati‐
2344 bility. Send us a report via perlbug if you are affected by this.
2345 See "Improved Perl version numbering system" for the reasons for
2347 this change.
2348 Literals of the form 1.2.3 parse differently
2350 Previously, numeric literals with more than one dot in them were
2351 interpreted as a floating point number concatenated with one or
2352 more numbers. Such "numbers" are now parsed as strings composed of
2353 the specified ordinals.
2354 For example, "print 97.98.99" used to output 97.9899 in earlier
2356 versions, but now prints "abc".
2357 See "Support for strings represented as a vector of ordinals".
2359 Possibly changed pseudo-random number generator
2361 Perl programs that depend on reproducing a specific set of pseudo-
2362 random numbers may now produce different output due to improvements
2363 made to the rand() builtin. You can use "sh Configure -Drand‐
2364 func=rand" to obtain the old behavior.
2365 See "Better pseudo-random number generator".
2367 Hashing function for hash keys has changed
2369 Even though Perl hashes are not order preserving, the apparently
2370 random order encountered when iterating on the contents of a hash
2371 is actually determined by the hashing algorithm used. Improvements
2372 in the algorithm may yield a random order that is different from
2373 that of previous versions, especially when iterating on hashes.
2374 See "Better worst-case behavior of hashes" for additional informa‐
2376 tion.
2377 "undef" fails on read only values
2379 Using the "undef" operator on a readonly value (such as $1) has the
2380 same effect as assigning "undef" to the readonly value--it throws
2381 an exception.
2382 Close-on-exec bit may be set on pipe and socket handles
2384 Pipe and socket handles are also now subject to the close-on-exec
2385 behavior determined by the special variable $^F.
2386 See "More consistent close-on-exec behavior".
2388 Writing "$$1" to mean "${$}1" is unsupported
2390 Perl 5.004 deprecated the interpretation of $$1 and similar within
2391 interpolated strings to mean "$$ . "1"", but still allowed it.
2392 In Perl 5.6.0 and later, "$$1" always means "${$1}".
2394 delete(), each(), values() and "\(%h)"
2396 operate on aliases to values, not copies
2397 delete(), each(), values() and hashes (e.g. "\(%h)") in a list con‐
2399 text return the actual values in the hash, instead of copies (as
2400 they used to in earlier versions). Typical idioms for using these
2401 constructs copy the returned values, but this can make a signifi‐
2402 cant difference when creating references to the returned values.
2403 Keys in the hash are still returned as copies when iterating on a
2404 hash.
2405 See also "delete(), each(), values() and hash iteration are
2407 faster".
2408 vec(EXPR,OFFSET,BITS) enforces powers-of-two BITS
2410 vec() generates a run-time error if the BITS argument is not a
2411 valid power-of-two integer.
2412 Text of some diagnostic output has changed
2414 Most references to internal Perl operations in diagnostics have
2415 been changed to be more descriptive. This may be an issue for pro‐
2416 grams that may incorrectly rely on the exact text of diagnostics
2417 for proper functioning.
2418 "%@" has been removed
2420 The undocumented special variable "%@" that used to accumulate
2421 "background" errors (such as those that happen in DESTROY()) has
2422 been removed, because it could potentially result in memory leaks.
2423 Parenthesized not() behaves like a list operator
2425 The "not" operator now falls under the "if it looks like a func‐
2426 tion, it behaves like a function" rule.
2427 As a result, the parenthesized form can be used with "grep" and
2429 "map". The following construct used to be a syntax error before,
2430 but it works as expected now:
2431 grep not($_), @things;
2433 On the other hand, using "not" with a literal list slice may not
2435 work. The following previously allowed construct:
2436 print not (1,2,3)[0];
2438 needs to be written with additional parentheses now:
2440 print not((1,2,3)[0]);
2442 The behavior remains unaffected when "not" is not followed by
2444 parentheses.
2445 Semantics of bareword prototype "(*)" have changed
2447 The semantics of the bareword prototype "*" have changed. Perl
2448 5.005 always coerced simple scalar arguments to a typeglob, which
2449 wasn't useful in situations where the subroutine must distinguish
2450 between a simple scalar and a typeglob. The new behavior is to not
2451 coerce bareword arguments to a typeglob. The value will always be
2452 visible as either a simple scalar or as a reference to a typeglob.
2453 See "More functional bareword prototype (*)".
2455 Semantics of bit operators may have changed on 64-bit platforms
2457 If your platform is either natively 64-bit or if Perl has been con‐
2458 figured to used 64-bit integers, i.e., $Config{ivsize} is 8, there
2459 may be a potential incompatibility in the behavior of bitwise
2460 numeric operators (& ⎪ ^ ~ << >>). These operators used to
2461 strictly operate on the lower 32 bits of integers in previous ver‐
2462 sions, but now operate over the entire native integral width. In
2463 particular, note that unary "~" will produce different results on
2464 platforms that have different $Config{ivsize}. For portability, be
2465 sure to mask off the excess bits in the result of unary "~", e.g.,
2466 "~$x & 0xffffffff".
2467 See "Bit operators support full native integer width".
2469 More builtins taint their results
2471 As described in "Improved security features", there may be more
2472 sources of taint in a Perl program.
2473 To avoid these new tainting behaviors, you can build Perl with the
2475 Configure option "-Accflags=-DINCOMPLETE_TAINTS". Beware that the
2476 ensuing perl binary may be insecure.
2477 C Source Incompatibilities
2479 "PERL_POLLUTE"
2481 Release 5.005 grandfathered old global symbol names by providing
2482 preprocessor macros for extension source compatibility. As of
2483 release 5.6.0, these preprocessor definitions are not available by
2484 default. You need to explicitly compile perl with "-DPERL_POLLUTE"
2485 to get these definitions. For extensions still using the old sym‐
2486 bols, this option can be specified via MakeMaker:
2487 perl Makefile.PL POLLUTE=1
2489 "PERL_IMPLICIT_CONTEXT"
2491 This new build option provides a set of macros for all API func‐
2492 tions such that an implicit interpreter/thread context argument is
2493 passed to every API function. As a result of this, something like
2494 "sv_setsv(foo,bar)" amounts to a macro invocation that actually
2495 translates to something like "Perl_sv_setsv(my_perl,foo,bar)".
2496 While this is generally expected to not have any significant source
2497 compatibility issues, the difference between a macro and a real
2498 function call will need to be considered.
2499 This means that there is a source compatibility issue as a result
2501 of this if your extensions attempt to use pointers to any of the
2502 Perl API functions.
2503 Note that the above issue is not relevant to the default build of
2505 Perl, whose interfaces continue to match those of prior versions
2506 (but subject to the other options described here).
2507 See "The Perl API" in perlguts for detailed information on the ram‐
2509 ifications of building Perl with this option.
2510 NOTE: PERL_IMPLICIT_CONTEXT is automatically enabled whenever Perl is built
2512 with one of -Dusethreads, -Dusemultiplicity, or both. It is not
2513 intended to be enabled by users at this time.
2514 "PERL_POLLUTE_MALLOC"
2516 Enabling Perl's malloc in release 5.005 and earlier caused the
2517 namespace of the system's malloc family of functions to be usurped
2518 by the Perl versions, since by default they used the same names.
2519 Besides causing problems on platforms that do not allow these func‐
2520 tions to be cleanly replaced, this also meant that the system ver‐
2521 sions could not be called in programs that used Perl's malloc.
2522 Previous versions of Perl have allowed this behaviour to be sup‐
2523 pressed with the HIDEMYMALLOC and EMBEDMYMALLOC preprocessor defi‐
2524 nitions.
2525 As of release 5.6.0, Perl's malloc family of functions have default
2527 names distinct from the system versions. You need to explicitly
2528 compile perl with "-DPERL_POLLUTE_MALLOC" to get the older behav‐
2529 iour. HIDEMYMALLOC and EMBEDMYMALLOC have no effect, since the be‐
2530 haviour they enabled is now the default.
2531 Note that these functions do not constitute Perl's memory alloca‐
2533 tion API. See "Memory Allocation" in perlguts for further informa‐
2534 tion about that.
2535 Compatible C Source API Changes
2537 "PATCHLEVEL" is now "PERL_VERSION"
2539 The cpp macros "PERL_REVISION", "PERL_VERSION", and "PERL_SUBVER‐
2540 SION" are now available by default from perl.h, and reflect the
2541 base revision, patchlevel, and subversion respectively.
2542 "PERL_REVISION" had no prior equivalent, while "PERL_VERSION" and
2543 "PERL_SUBVERSION" were previously available as "PATCHLEVEL" and
2544 "SUBVERSION".
2545 The new names cause less pollution of the cpp namespace and reflect
2547 what the numbers have come to stand for in common practice. For
2548 compatibility, the old names are still supported when patchlevel.h
2549 is explicitly included (as required before), so there is no source
2550 incompatibility from the change.
2551 Binary Incompatibilities
2553 In general, the default build of this release is expected to be binary
2555 compatible for extensions built with the 5.005 release or its mainte‐
2556 nance versions. However, specific platforms may have broken binary
2557 compatibility due to changes in the defaults used in hints files.
2558 Therefore, please be sure to always check the platform-specific README
2559 files for any notes to the contrary.
2560 The usethreads or usemultiplicity builds are not binary compatible with
2562 the corresponding builds in 5.005.
2563 On platforms that require an explicit list of exports (AIX, OS/2 and
2565 Windows, among others), purely internal symbols such as parser func‐
2566 tions and the run time opcodes are not exported by default. Perl 5.005
2567 used to export all functions irrespective of whether they were consid‐
2568 ered part of the public API or not.
2569 For the full list of public API functions, see perlapi.
2571
2573 Thread test failures
2574 The subtests 19 and 20 of lib/thr5005.t test are known to fail due to
2576 fundamental problems in the 5.005 threading implementation. These are
2577 not new failures--Perl 5.005_0x has the same bugs, but didn't have
2578 these tests.
2579 EBCDIC platforms not supported
2581 In earlier releases of Perl, EBCDIC environments like OS390 (also known
2583 as Open Edition MVS) and VM-ESA were supported. Due to changes
2584 required by the UTF-8 (Unicode) support, the EBCDIC platforms are not
2585 supported in Perl 5.6.0.
2586 In 64-bit HP-UX the lib/io_multihomed test may hang
2588 The lib/io_multihomed test may hang in HP-UX if Perl has been config‐
2590 ured to be 64-bit. Because other 64-bit platforms do not hang in this
2591 test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
2592 test attempts to create and connect to "multihomed" sockets (sockets
2593 which have multiple IP addresses).
2594 NEXTSTEP 3.3 POSIX test failure
2596 In NEXTSTEP 3.3p2 the implementation of the strftime(3) in the operat‐
2598 ing system libraries is buggy: the %j format numbers the days of a
2599 month starting from zero, which, while being logical to programmers,
2600 will cause the subtests 19 to 27 of the lib/posix test may fail.
2601 Tru64 (aka Digital UNIX, aka DEC OSF/1) lib/sdbm test failure with gcc
2603 If compiled with gcc 2.95 the lib/sdbm test will fail (dump core). The
2605 cure is to use the vendor cc, it comes with the operating system and
2606 produces good code.
2607 UNICOS/mk CC failures during Configure run
2609 In UNICOS/mk the following errors may appear during the Configure run:
2611 Guessing which symbols your C compiler and preprocessor define...
2613 CC-20 cc: ERROR File = try.c, Line = 3
2614 ...
2615 bad switch yylook 79bad switch yylook 79bad switch yylook 79bad switch yylook 79#ifdef A29K
2616 ...
2617 4 errors detected in the compilation of "try.c".
2618 The culprit is the broken awk of UNICOS/mk. The effect is fortunately
2620 rather mild: Perl itself is not adversely affected by the error, only
2621 the h2ph utility coming with Perl, and that is rather rarely needed
2622 these days.
2623 Arrow operator and arrays
2625 When the left argument to the arrow operator "->" is an array, or the
2627 "scalar" operator operating on an array, the result of the operation
2628 must be considered erroneous. For example:
2629 @x->[2]
2631 scalar(@x)->[2]
2632 These expressions will get run-time errors in some future release of
2634 Perl.
2635 Experimental features
2637 As discussed above, many features are still experimental. Interfaces
2639 and implementation of these features are subject to change, and in
2640 extreme cases, even subject to removal in some future release of Perl.
2641 These features include the following:
2642 Threads
2644 Unicode
2645 64-bit support
2646 Lvalue subroutines
2647 Weak references
2648 The pseudo-hash data type
2649 The Compiler suite
2650 Internal implementation of file globbing
2651 The DB module
2652 The regular expression code constructs:
2653 "(?{ code })" and "(??{ code })"
2654
2656 Character class syntax [: :] is reserved for future extensions
2657 (W) Within regular expression character classes ([]) the syntax
2658 beginning with "[:" and ending with ":]" is reserved for future
2659 extensions. If you need to represent those character sequences
2660 inside a regular expression character class, just quote the square
2661 brackets with the backslash: "\[:" and ":\]".
2662 Ill-formed logical name ⎪%s⎪ in prime_env_iter
2664 (W) A warning peculiar to VMS. A logical name was encountered when
2665 preparing to iterate over %ENV which violates the syntactic rules
2666 governing logical names. Because it cannot be translated normally,
2667 it is skipped, and will not appear in %ENV. This may be a benign
2668 occurrence, as some software packages might directly modify logical
2669 name tables and introduce nonstandard names, or it may indicate
2670 that a logical name table has been corrupted.
2671 In string, @%s now must be written as \@%s
2673 The description of this error used to say:
2674 (Someday it will simply assume that an unbackslashed @
2676 interpolates an array.)
2677 That day has come, and this fatal error has been removed. It has
2679 been replaced by a non-fatal warning instead. See "Arrays now
2680 always interpolate into double-quoted strings" for details.
2681 Probable precedence problem on %s
2683 (W) The compiler found a bareword where it expected a conditional,
2684 which often indicates that an ⎪⎪ or && was parsed as part of the
2685 last argument of the previous construct, for example:
2686 open FOO ⎪⎪ die;
2688 regexp too big
2690 (F) The current implementation of regular expressions uses shorts
2691 as address offsets within a string. Unfortunately this means that
2692 if the regular expression compiles to longer than 32767, it'll blow
2693 up. Usually when you want a regular expression this big, there is
2694 a better way to do it with multiple statements. See perlre.
2695 Use of "$$<digit>" to mean "${$}<digit>" is deprecated
2697 (D) Perl versions before 5.004 misinterpreted any type marker fol‐
2698 lowed by "$" and a digit. For example, "$$0" was incorrectly taken
2699 to mean "${$}0" instead of "${$0}". This bug is (mostly) fixed in
2700 Perl 5.004.
2701 However, the developers of Perl 5.004 could not fix this bug com‐
2703 pletely, because at least two widely-used modules depend on the old
2704 meaning of "$$0" in a string. So Perl 5.004 still interprets
2705 "$$<digit>" in the old (broken) way inside strings; but it gener‐
2706 ates this message as a warning. And in Perl 5.005, this special
2707 treatment will cease.
2708
2710 If you find what you think is a bug, you might check the articles
2711 recently posted to the comp.lang.perl.misc newsgroup. There may also
2712 be information at http://www.perl.com/perl/ , the Perl Home Page.
2713 If you believe you have an unreported bug, please run the perlbug pro‐
2715 gram included with your release. Be sure to trim your bug down to a
2716 tiny but sufficient test case. Your bug report, along with the output
2717 of "perl -V", will be sent off to perlbug@perl.org to be analysed by
2718 the Perl porting team.
2719
2721 The Changes file for exhaustive details on what changed.
2722 The INSTALL file for how to build Perl.
2724 The README file for general stuff.
2726 The Artistic and Copying files for copyright information.
2728
2730 Written by Gurusamy Sarathy <gsar@activestate.com>, with many contribu‐
2731 tions from The Perl Porters.
2732 Send omissions or corrections to <perlbug@perl.org>.
2734perl v5.8.8 2006-01-07 PERL56DELTA(1)