=head1 NAME
-perldelta - what's new for perl v5.6 (as of v5.005_62)
+perldelta - what's new for perl v5.6 (as of v5.005_64)
=head1 DESCRIPTION
=head2 Perl Source Incompatibilities
-Beware that any new warnings that have been added are B<not> considered
-incompatible changes.
+Beware that any new warnings that have been added or old ones
+that have been enhanced are B<not> considered incompatible changes.
Since all new warnings must be explicitly requested via the C<-w>
switch or the C<warnings> pragma, it is ultimately the programmer's
=over 4
+=item CHECK is a new keyword
+
+In addition to C<BEGIN>, C<INIT>, C<END>, C<DESTROY> and C<AUTOLOAD>,
+subroutines named C<CHECK> are now special. These are queued up during
+compilation and behave similar to END blocks, except they are called at
+the end of compilation rather than at the end of execution. They cannot
+be called directly.
+
=item Treatment of list slices of undef has changed
When taking a slice of a literal list (as opposed to a slice of
rand(3) function. As of 5.005_52, Configure tests for drand48(),
random(), and rand() (in that order) and picks the first one it finds.
Perl programs that depend on reproducing a specific set of pseudo-random
-numbers will now likely produce different output.
+numbers will now likely produce different output. You can use
+C<sh Configure -Drandfunc=rand> to obtain the old behavior.
=item Hashing function for hash keys has changed
the same effect as assigning C<undef> to the readonly value--it
throws an exception.
-=item Close-on-exec bit may be set on pipe() handles
+=item Close-on-exec bit may be set on pipe and socket handles
On systems that support a close-on-exec flag on filehandles, the
-flag will be set for any handles created by pipe(), if that is
-warranted by the value of $^F that may be in effect. Earlier
-versions neglected to set the flag for handles created with
-pipe(). See L<perlfunc/pipe> and L<perlvar/$^F>.
+flag will be set for any handles created by pipe(), socketpair(),
+socket(), and accept(), if that is warranted by the value of $^F
+that may be in effect. Earlier versions neglected to set the flag
+for handles created with these operators. See L<perlfunc/pipe>,
+L<perlfunc/socketpair>, L<perlfunc/socket>, L<perlfunc/accept>,
+and L<perlvar/$^F>.
=item Writing C<"$$1"> to mean C<"${$}1"> is unsupported
In Perl 5.6 and later, C<"$$1"> always means C<"${$1}">.
-=item values(%h) and C<\(%h)> operate on aliases to values, not copies
+=item delete(), values() and C<\(%h)> operate on aliases to values, not copies
-each(), values() and hashes in a list context return the actual
+delete(), each(), values() and hashes in a list context return the actual
values in the hash, instead of copies (as they used to in earlier
versions). Typical idioms for using these constructs copy the
-returned values, but this is can make a significant difference when
+returned values, but this can make a significant difference when
creating references to the returned values.
Keys in the hash are still returned as copies when iterating on
has been removed, because it could potentially result in memory
leaks.
+=item Parenthesized not() behaves like a list operator
+
+The C<not> operator now falls under the "if it looks like a function,
+it behaves like a function" rule.
+
+As a result, the parenthesized form can be used with C<grep> and C<map>.
+The following construct used to be a syntax error before, but it works
+as expected now:
+
+ grep not($_), @things;
+
+On the other hand, using C<not> with a literal list slice may not
+work. The following previously allowed construct:
+
+ print not (1,2,3)[0];
+
+needs to be written with additional parentheses now:
+
+ print not((1,2,3)[0]);
+
+The behavior remains unaffected when C<not> is not followed by parentheses.
+
+=item Semantics of bareword prototype C<(*)> have changed
+
+Arguments prototyped as C<*> will now be visible within the subroutine
+as either a simple scalar or as a reference to a typeglob. Perl 5.005
+always coerced simple scalar arguments to a typeglob, which wasn't useful
+in situations where the subroutine must distinguish between a simple
+scalar and a typeglob. See L<perlsub/Prototypes>.
+
=back
=head2 C Source Incompatibilities
=item C<PERL_IMPLICIT_CONTEXT>
+PERL_IMPLICIT_CONTEXT is automatically enabled whenever Perl is built
+with one of -Dusethreads, -Dusemultiplicity, or both. It is not
+intended to be enabled by users at this time.
+
This new build option provides a set of macros for all API functions
such that an implicit interpreter/thread context argument is passed to
every API function. As a result of this, something like C<sv_setsv(foo,bar)>
Perl, whose interfaces continue to match those of prior versions
(but subject to the other options described here).
-PERL_IMPLICIT_CONTEXT is automatically enabled whenever Perl is built
-with one of -Dusethreads, -Dusemultiplicity, or both.
-
See L<perlguts/"The Perl API"> for detailed information on the
ramifications of building Perl using this option.
Note that these functions do B<not> constitute Perl's memory allocation API.
See L<perlguts/"Memory Allocation"> for further information about that.
-=item C<PL_na> and C<dTHR> Issues
-
-The C<PL_na> global is now thread local, so a C<dTHR> declaration is needed
-in the scope in which the global appears. XSUBs should handle this automatically,
-but if you have used C<PL_na> in support functions, you either need to
-change the C<PL_na> to a local variable (which is recommended), or put in
-a C<dTHR>.
-
=back
=head2 Compatible C Source API Changes
=head2 Binary Incompatibilities
-The default build of this release is binary compatible with the 5.005
-release or its maintenance versions.
+In general, the default build of this release is expected to be binary
+compatible for extensions built with the 5.005 release or its maintenance
+versions. However, specific platforms may have broken binary compatibility
+due to changes in the defaults used in hints files. Therefore, please be
+sure to always check the platform-specific README files for any notes to
+the contrary.
The usethreads or usemultiplicity builds are B<not> binary compatible
with the corresponding builds in 5.005.
+On platforms that require an explicit list of exports (AIX, OS/2 and Windows,
+among others), purely internal symbols such as parser functions and the
+run time opcodes are not exported by default. Perl 5.005 used to export
+all functions irrespective of whether they were considered part of the
+public API or not.
+
+For the full list of public API functions, see L<perlapi>.
+
=head1 Installation and Configuration Improvements
+=head2 -Dusethreads means something different
+
+WARNING: Support for threads continues to be an experimental feature.
+Interfaces and implementation are subject to sudden and drastic changes.
+
+The -Dusethreads flag now enables the experimental interpreter-based thread
+support by default. To get the flavor of experimental threads that was in
+5.005 instead, you need to ask for -Duse5005threads.
+
+As of v5.5.640, interpreter-threads support is still lacking a way to
+create new threads from Perl (i.e., C<use Thread;> will not work with
+interpreter threads). C<use Thread;> continues to be available when you
+ask for -Duse5005threads, bugs and all.
+
+=head2 Perl's version numbering has changed
+
+Beginning with Perl version 5.6, the version number convention has been
+changed to a "dotted tuple" scheme that is more commonly found in open
+source projects.
+
+Maintenance versions of v5.6.0 will be released as v5.6.1, v5.6.2 etc.
+The next development series following v5.6 will be numbered v5.7.x,
+beginning with v5.7.0, and the next major production release following
+v5.6 will be v5.8.
+
+The v1.2.3 syntax is also now legal in Perl. See L<Support for version tuples>
+for more on that.
+
+To cope with the new versioning system's use of at least three significant
+digits for each version component, the method used for incrementing the
+subversion number has also changed slightly. We assume that versions older
+than v5.6 have been incrementing the subversion component in multiples of
+10. Versions after v5.6 will increment them by 1. Thus, using the new
+notation, 5.005_03 is the same as v5.5.30, and the first maintenance
+version following v5.6 will be v5.6.1, which amounts to a floating point
+value of 5.006_001).
+
=head2 New Configure flags
The following new flags may be enabled on the Configure command line
by running Configure with C<-Dflag>.
usemultiplicity
+ use5005threads
uselongdouble
usemorebits
=head2 -Dusethreads and -Duse64bits now more daring
The Configure options enabling the use of threads and the use of
-64-bitness are now more daring in the sense that they no more have
-an explicit list of operating systems of known threads/64-bit
+64-bitness are now more daring in the sense that they no more have an
+explicit list of operating systems of known threads/64-bit
capabilities. In other words: if your operating system has the
-necessary APIs, you should be able just to go ahead and use them.
-See also L<"64-bit support">.
+necessary APIs and datatypes, you should be able just to go ahead and
+use them, for threads by Configure -Dusethreads, and for 64 bits
+either explicitly by Configure -Duse64bits or implicitly if your
+system has 64 bit wide datatypes. See also L<"64-bit support">.
=head2 Long Doubles
Some platforms have "long doubles", floating point numbers of even
-larger range than ordinary "doubles". To enable using ng doubles for
+larger range than ordinary "doubles". To enable using long doubles for
Perl's scalars, use -Duselongdouble.
=head2 -Dusemorebits
=head2 SOCKS support
You can use "Configure -Dusesocks" which causes Perl to probe
-for the SOCKS proxy protocol library, http://www.socks.nec.com/
+for the SOCKS (v5, not v4) proxy protocol library,
+http://www.socks.nec.com/
=head2 C<-A> flag
hints files have been processed but before the actual configuration
process starts. Run C<Configure -h> to find out the full C<-A> syntax.
-=head2 New Installation Scheme
+=head2 Enhanced Installation Directories
-vendorprefix et al
-[TODO - Andy Dougherty <doughera@lafcol.lafayette.edu>]
+The installation structure has been enriched to improve the support for
+maintaining multiple versions of perl, to provide locations for
+vendor-supplied modules and scripts, and to ease maintenance of
+locally-added modules and scripts. See the section on Installation
+Directories in the INSTALL file for complete details. For most users
+building and installing from source, the defaults should be fine.
=head1 Core Changes
=head2 Unicode and UTF-8 support
Perl can optionally use UTF-8 as its internal representation for character
-strings. The C<utf8> pragma enables this support in the current lexical
-scope. See L<utf8> for more information.
+strings. The C<utf8> and C<bytes> pragmas are used to control this support
+in the current lexical scope. See L<perlunicode>, L<utf8> and L<bytes> for
+more information.
+
+=head2 Interpreter cloning, threads, and concurrency
+
+WARNING: This is an experimental feature in a pre-alpha state. Use
+at your own risk.
+
+Perl 5.005_63 introduces the beginnings of support for running multiple
+interpreters concurrently in different threads. In conjunction with
+the perl_clone() API call, which can be used to selectively duplicate
+the state of any given interpreter, it is possible to compile a
+piece of code once in an interpreter, clone that interpreter
+one or more times, and run all the resulting interpreters in distinct
+threads.
+
+On Windows, this feature is used to emulate fork() at the interpreter
+level. See L<perlfork>.
+
+This feature is still in evolution. It is eventually meant to be used
+to selectively clone a subroutine and data reachable from that
+subroutine in a separate interpreter and run the cloned subroutine
+in a separate thread. Since there is no shared data between the
+interpreters, little or no locking will be needed (unless parts of
+the symbol table are explicitly shared). This is obviously intended
+to be an easy-to-use replacement for the existing threads support.
+
+Support for cloning interpreters and interpreter concurrency can be
+enabled using the -Dusethreads Configure option (see win32/Makefile for
+how to enable it on Windows.) The resulting perl executable will be
+functionally identical to one that was built with -Dmultiplicity, but
+the perl_clone() API call will only be available in the former.
+
+-Dusethreads enables, the cpp macros USE_ITHREADS by default, which enables
+Perl source code changes that provide a clear separation between the op tree
+and the data it operates with. The former is considered immutable, and can
+therefore be shared between an interpreter and all of its clones, while the
+latter is considered local to each interpreter, and is therefore copied for
+each clone.
+
+Note that building Perl with the -Dusemultiplicity Configure option
+is adequate if you wish to run multiple B<independent> interpreters
+concurrently in different threads. -Dusethreads only provides the
+additional functionality of the perl_clone() API call and other
+support for running B<cloned> interpreters concurrently.
+
+[XXX TODO - the Compiler backends may be broken when USE_ITHREADS is
+enabled.]
=head2 Lexically scoped warning categories
change#4081
[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>,
-Tuomas Lukka <lukka@fas.harvard.edu>)]
+Tuomas Lukka <lukka@iki.fi>)]
=head2 "our" declarations
An "our" declaration introduces a value that can be best understood
as a lexically scoped symbolic alias to a global variable in the
-current package. This is mostly useful as an alternative to the
-C<vars> pragma, but also provides the opportunity to introduce
-typing and other attributes for such variables. See L<perlfunc/our>.
+package that was current where the variable was declared. This is
+mostly useful as an alternative to the C<vars> pragma, but also provides
+the opportunity to introduce typing and other attributes for such
+variables. See L<perlfunc/our>.
+
+=head2 Support for version tuples
+
+Literals of the form v1.2.3.4 are now parsed as the utf8 string
+C<"\x{1}\x{2}\x{3}\x{4}">. This allows comparing version numbers using
+regular string comparison operators C<eq>, C<ne>, C<lt>, C<gt> etc.
+
+These "dotted tuples" are dual-valued. They are both strings of utf8
+characters, and floating point numbers. Thus v1.2.3.4 has the string
+value C<"\x{1}\x{2}\x{3}\x{4}"> and the numeric value 1.002_003_004.
+As another example, v5.5.640 has the string value C<"\x{5}\x{5}\x{280}">
+(remember 280 hexadecimal is 640 decimal) and the numeric value
+5.005_64.
+
+In conjunction with the new C<$^V> magic variable (which contains
+the perl version in this format), such literals can be used to
+check if you're running a particular version of Perl.
+
+ if ($^V and $^V gt v5.5.640) {
+ # new style version numbers are supported
+ }
+
+C<require> and C<use> also support such literals:
+
+ require v5.6.0; # croak if $^V lt v5.6.0
+ use v5.6.0; # same, but croaks at compile-time
+
+C<sprintf> and C<printf> support the Perl-specific format type C<%v>
+to print arbitrary strings as dotted tuples.
+
+ printf "v%v", $^V; # prints current version, such as "v5.5.650"
=head2 Weak references
WARNING: This is an experimental feature.
+In previous versions of Perl, you couldn't cache objects so as
+to allow them to be deleted if the last reference from outside
+the cache is deleted. The reference in the cache would hold a
+reference count on the object and the objects would never be
+destroyed.
+
+Another familiar problem is with circular references. When an
+object references itself, its reference count would never go
+down to zero, and it would not get destroyed until the program
+is about to exit.
+
+Weak references solve this by allowing you to "weaken" any
+reference, that is, make it not count towards the reference count.
+When the last non-weak reference to an object is deleted, the object
+is destroyed and all the weak references to the object are
+automatically undef-ed.
+
+To use this feature, you need the WeakRef package from CPAN, which
+contains additional documentation.
+
change#3385, also need perlguts documentation
+[TODO - Tuomas Lukka <lukka@iki.fi>]
+
+=head2 File globbing implemented internally
+
+WARNING: This is currently an experimental feature. Interfaces and
+implementation are likely to change.
-[TODO - Tuomas Lukka <lukka@fas.harvard.edu>]
+Perl now uses the File::Glob implementation of the glob() operator
+automatically. This avoids using an external csh process and the
+problems associated with it.
=head2 Binary numbers supported
Perl now allows the arrow to be omitted in many constructs
involving subroutine calls through references. For example,
-C<$foo[10]->('foo')> may now be written C<$foo[10]('foo')>.
+C<$foo[10]-E<gt>('foo')> may now be written C<$foo[10]('foo')>.
This is rather similar to how the arrow may be omitted from
-C<$foo[10]->{'foo'}>. Note however, that the arrow is still
-required for C<foo(10)->('bar')>.
+C<$foo[10]-E<gt>{'foo'}>. Note however, that the arrow is still
+required for C<foo(10)-E<gt>('bar')>.
+
+=head2 exists() is supported on subroutine names
+
+The exists() builtin now works on subroutine names. A subroutine
+is considered to exist if it has been declared (even if implicitly).
+See L<perlfunc/exists> for examples.
+
+=head2 exists() and delete() are supported on array elements
+
+The exists() and delete() builtins now work on simple arrays as well.
+The behavior is similar to that on hash elements.
+
+exists() can be used to check whether an array element has been
+initialized. This avoids autovivifying array elements that don't exist.
+If the array is tied, the EXISTS() method in the corresponding tied
+package will be invoked.
+
+delete() may be used to remove an element from the array and return
+it. The array element at that position returns to its unintialized
+state, so that testing for the same element with exists() will return
+false. If the element happens to be the one at the end, the size of
+the array also shrinks up to the highest element that tests true for
+exists(), or 0 if none such is found. If the array is tied, the DELETE()
+method in the corresponding tied package will be invoked.
+
+See L<perlfunc/exists> and L<perlfunc/delete> for examples.
=head2 syswrite() ease-of-use
The length argument of C<syswrite()> has become optional.
-=head2 Filehandles can be autovivified
+=head2 File and directory handles can be autovivified
-The construct C<open(my $fh, ...)> can be used to create filehandles
-more easily. The filehandle will be automatically closed at the end
-of the scope of $fh, provided there are no other references to it. This
-largely eliminates the need for typeglobs when opening filehandles
-that must be passed around, as in the following example:
+Similar to how constructs such as C<$x-E<gt>[0]> autovivify a reference,
+handle constructors (open(), opendir(), pipe(), socketpair(), sysopen(),
+socket(), and accept()) now autovivify a file or directory handle
+if the handle passed to them is an uninitialized scalar variable. This
+allows the constructs such as C<open(my $fh, ...)> and C<open(local $fh,...)>
+to be used to create filehandles that will conveniently be closed
+automatically when the scope ends, provided there are no other references
+to them. This largely eliminates the need for typeglobs when opening
+filehandles that must be passed around, as in the following example:
sub myopen {
open my $fh, "@_"
and compile Perl using the -Duse64bits Configure flag.
Unfortunately bit arithmetics (&, |, ^, ~, <<, >>) for numbers are not
-64-bit clean, they are explictly forced to be 32-bit. Bit arithmetics
-for bit vectors (created by vec()) are not limited in their width.
+64-bit clean, they are explictly forced to be 32-bit because of
+tangled backward compatibility issues. This limitation is subject to
+change. Bit arithmetics for bit vector scalars (created by vec()) are
+not limited in their width, you can use the & | ^ ~ operators on such
+scalars.
Last but not least: note that due to Perl's habit of always using
floating point numbers the quads are still not true integers.
If you have filesystems that support "large files" (files larger than
2 gigabytes), you may now also be able to create and access them from
Perl. You have to use Configure -Duselargefiles. Turning on the
-large file support turns on also the 64-bit support, for obvious reasons.
+large file support turns on also the 64-bit support on many platforms.
+Beware that unless your filesystem also supports "sparse files" seeking
+to umpteen petabytes may be unadvisable.
Note that in addition to requiring a proper file system to do large
files you may also need to adjust your per-process (or your
included with the standard Perl distribution) may also be of use, it
offers the getrlimit/setrlimit interface that can be used to adjust
process resource usage limits, including the maximum filesize limit.
-
+
=head2 Long doubles
In some systems you may be able to use long doubles to enhance the
-range of precision of your double precision floating point numbers
+range and precision of your double precision floating point numbers
(that is, Perl's numbers). Use Configure -Duselongdouble to enable
this support (if it is available).
=head2 "more bits"
-You can Configure -Dusemorebits to turn on both the 64-bit support
+You can "Configure -Dusemorebits" to turn on both the 64-bit support
and the long double support.
+=head2 Enhanced support for sort() subroutines
+
+Perl subroutines with a prototype of C<($$)> and XSUBs in general can
+now be used as sort subroutines. In either case, the two elements to
+be compared are passed as normal parameters in @_. See L<perlfunc/sort>.
+
+For unprototyped sort subroutines, the historical behavior of passing
+the elements to be compared as the global variables $a and $b remains
+unchanged.
+
=head2 Better syntax checks on parenthesized unary operators
Expressions such as:
Formerly, if you wanted to mark a subroutine as being a method call or
as requiring an automatic lock() when it is entered, you had to declare
that with a C<use attrs> pragma in the body of the subroutine.
-That can now be accomplished with a declaration syntax, like this:
+That can now be accomplished with declaration syntax, like this:
- sub mymethod : locked, method ;
+ sub mymethod : locked method ;
...
- sub mymethod : locked, method {
+ sub mymethod : locked method {
...
}
+ sub othermethod :locked :method ;
+ ...
+ sub othermethod :locked :method {
+ ...
+ }
+
+
+(Note how only the first C<:> is mandatory, and whitespace surrounding
+the C<:> is optional.)
+
F<AutoSplit.pm> and F<SelfLoader.pm> have been updated to keep the attributes
with the stubs they provide. See L<attributes>.
enables perl code to determine whether actions that make sense
only during normal running are warranted. See L<perlvar>.
+=head2 New variable $^V contains Perl version in v5.6.0 format
+
+C<$^V> contains the Perl version number as a version tuple that
+can be used in string or numeric comparisons. See
+C<Support for version tuples> for an example.
+
=head2 Optional Y2K warnings
If Perl is built with the cpp macro C<PERL_Y2KWARN> defined,
with another number.
This behavior must be specifically enabled when running Configure.
-See L<INSTALL> and L<README.Y2K>.
+See F<INSTALL> and F<README.Y2K>.
=head1 Significant bug fixes
=head2 E<lt>HANDLEE<gt> on empty files
-With C<$/> set to C<undef>, slurping an empty file returns a string of
+With C<$/> set to C<undef>, "slurping" an empty file returns a string of
zero length (instead of C<undef>, as it used to) the first time the
-HANDLE is read. Further reads yield C<undef>.
+HANDLE is read after C<$/> is set to C<undef>. Further reads yield
+C<undef>.
This means that the following will append "foo" to an empty file (it used
to do nothing):
on C<OLD>. Formerly, it would have returned the data from the start
of the following disk block instead.
+=head2 eof() has the same old magic as <>
+
+C<eof()> would return true if no attempt to read from C<E<lt>E<gt>> had
+yet been made. C<eof()> has been changed to have a little magic of its
+own, it now opens the C<E<lt>E<gt>> files.
+
=head2 system(), backticks and pipe open now reflect exec() failure
On Unix and similar platforms, system(), qx() and open(FOO, "cmd |")
since the exec() happened to be in a different process.
The child process now communicates with the parent about the
-error in launching the external command, which allow these
+error in launching the external command, which allows these
constructs to return with their usual error value and set $!.
=head2 Implicitly closed filehandles are safer
=head2 Pseudo-hashes work better
Dereferencing some types of reference values in a pseudo-hash,
-such as C<$ph->{foo}[1]>, was accidentally disallowed. This has
+such as C<$ph-E<gt>{foo}[1]>, was accidentally disallowed. This has
been corrected.
When applied to a pseudo-hash element, exists() now reports whether
the specified value exists, not merely if the key is valid.
+delete() now works on pseudo-hashes. When given a pseudo-hash element
+or slice it deletes the values corresponding to the keys (but not the keys
+themselves). See L<perlref/"Pseudo-hashes: Using an array as a hash">.
+
=head2 C<goto &sub> and AUTOLOAD
The C<goto &sub> construct works correctly when C<&sub> happens
=head2 Locale bugs fixed
-printf() and sprintf() previously did reset the numeric locale
+printf() and sprintf() previously reset the numeric locale
back to the default "C" locale. This has been fixed.
Numbers formatted according to the local numeric locale
behavior, END blocks are not executed anymore when the C<-c> switch
is used.
-Note that something resembling the previous behavior can still be
-obtained by putting C<BEGIN { $^C = 0; exit; } at the very end of
-the top level source file.
+See L<CHECK blocks> for how to run things when the compile phase ends.
=head2 Potential to leak DATA filehandles
=head2 Other fixes for better diagnostics
-Line numbers are suppressed no more (under most likely circumstances)
+Line numbers are no longer suppressed (under most likely circumstances)
during the global destruction phase.
Diagnostics emitted from code running in threads other than the main
$foo::a and $foo::b are now exempt from "possible typo" warnings only
if sort() is encountered in package foo.
-Unrecognized alphabetic escapes encountered when parsing quoting
+Unrecognized alphabetic escapes encountered when parsing quote
constructs now generate a warning, since they may take on new
semantics in later versions of Perl.
=head2 DOS
-[TODO - Laszlo Molnar <laszlo.molnar@eth.ericsson.se>]
+=over 4
+
+=item *
+
+Perl now works with djgpp 2.02 (and 2.03 alpha).
+
+=item *
+
+Environment variable names are not converted to uppercase any more.
+
+=item *
+
+Wrong exit code from backticks now fixed.
+
+=item *
+
+This port is still using its own builtin globbing.
+
+=back
=head2 OS/2
Rudimentary support for building under command.com in Windows 95
has been added.
+Scripts are read in binary mode by default to allow ByteLoader (and
+the filter mechanism in general) to work properly. For compatibility,
+the DATA filehandle will be set to text mode if a carriage return is
+detected at the end of the line containing the __END__ or __DATA__
+token; if not, the DATA filehandle will be left open in binary mode.
+Earlier versions always opened the DATA filehandle in text mode.
+
+The glob() operator is implemented via the L<File::Glob> extension,
+which supports glob syntax of the C shell. This increases the flexibility
+of the glob() operator, but there may be compatibility issues for
+programs that relied on the older globbing syntax. If you want to
+preserve compatibility with the older syntax, you might want to put
+a C<use File::DosGlob;> in your program. For details and compatibility
+information, see L<File::Glob>.
+
[TODO - GSAR]
=head1 New tests
Verify operations that access pad objects (lexicals and temporaries).
+=item op/exists_sub
+
+Verify C<exists &sub> operations.
+
=back
=head1 Modules and Pragmata
=item B
+The Perl Compiler suite has been extensively reworked for this
+release.
+
[TODO - Vishal Bhatia <vishal@gol.com>,
Nick Ing-Simmons <nick@ni-s.u-net.com>]
The ByteLoader is a dedicated extension to generate and run
Perl bytecode. See L<ByteLoader>.
-=item B
+=item constant
-The Perl Compiler suite has been extensively reworked for this
-release.
+References can now be used.
-=item constant
+The new version also allows a leading underscore in constant names, but
+disallows a double leading underscore (as in "__LINE__"). Some other names
+are disallowed or warned against, including BEGIN, END, etc. Some names
+which were forced into main:: used to fail silently in some cases; now they're
+fatal (outside of main::) and an optional warning (inside of main::).
+The ability to detect whether a constant had been set with a given name has
+been added.
-References can now be used. See L<constant>.
+See L<constant>.
=item charnames
=item Data::Dumper
A C<Maxdepth> setting can be specified to avoid venturing
-too deeply into data structures that may be very deep.
-See L<Data::Dumper>.
+too deeply into deep data structures. See L<Data::Dumper>.
Dumping C<qr//> objects works correctly.
=item DB_File
-[TODO - Paul Marquess <paul.marquess@bt.com>]
+DB_File can now be built with Berkeley DB versions 1, 2 or 3.
+See C<ext/DB_File/Changes>.
=item Devel::DProf
-Devel::DProf, a Perl source code profiler has been added. See L<DProf>.
+Devel::DProf, a Perl source code profiler has been added. See
+L<Devel::DProf> and L<dprofpp>.
=item Dumpvalue
-Added Dumpvalue module provides screen dumps of Perl data.
+The Dumpvalue module provides screen dumps of Perl data.
=item Benchmark
+Overall, Benchmark results exhibit lower average error and better timing
+accuracy.
+
You can now run tests for I<n> seconds instead of guessing the right
number of tests to run: e.g. timethese(-5, ...) will run each
code for at least 5 CPU seconds. Zero as the "number of repetitions"
means "for at least 3 CPU seconds". The output format has also
changed. For example:
-use Benchmark;$x=3;timethese(-5,{a=>sub{$x*$x},b=>sub{$x**2}})
+ use Benchmark;$x=3;timethese(-5,{a=>sub{$x*$x},b=>sub{$x**2}})
will now output something like this:
-Benchmark: running a, b, each for at least 5 CPU seconds...
- a: 5 wallclock secs ( 5.77 usr + 0.00 sys = 5.77 CPU) @ 200551.91/s (n=1156516)
- b: 4 wallclock secs ( 5.00 usr + 0.02 sys = 5.02 CPU) @ 159605.18/s (n=800686)
+ Benchmark: running a, b, each for at least 5 CPU seconds...
+ a: 5 wallclock secs ( 5.77 usr + 0.00 sys = 5.77 CPU) @ 200551.91/s (n=1156516)
+ b: 4 wallclock secs ( 5.00 usr + 0.02 sys = 5.02 CPU) @ 159605.18/s (n=800686)
New features: "each for at least N CPU seconds...", "wallclock secs",
and the "@ operations/CPU second (n=operations)".
-change#4265,4266,4292
-[TODO - Barrie Slaymaker <barries@slaysys.com>]
+timethese() now returns a reference to a hash of Benchmark objects containing
+the test results, keyed on the names of the tests.
+
+timethis() now returns the iterations field in the Benchmark result object
+instead of 0.
+
+timethese(), timethis(), and the new cmpthese() (see below) can also take
+a format specifier of 'none' to suppress output.
+
+A new function countit() is just like timeit() except that it takes a
+TIME instead of a COUNT.
+
+A new function cmpthese() prints a chart comparing the results of each test
+returned from a timethese() call. For each possible pair of tests, the
+percentage speed difference (iters/sec or seconds/iter) is shown.
+
+For other details, see L<Benchmark>.
=item Devel::Peek
=item Fcntl
More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for
-large (more than 4G) file access (64-bit support is not yet
-working, though, so no need to get overly excited), Free/Net/OpenBSD
-locking behaviour flags F_FLOCK, F_POSIX, Linux F_SHLCK, and
-O_ACCMODE: the mask of O_RDONLY, O_WRONLY, and O_RDWR.
+large file (more than 4GB) access Note that the O_LARGEFILE is
+automatically/transparently added to sysopen() flags if large file
+support has been configured), Free/Net/OpenBSD locking behaviour flags
+F_FLOCK, F_POSIX, Linux F_SHLCK, and O_ACCMODE: the combined mask of
+O_RDONLY, O_WRONLY, and O_RDWR. The seek()/sysseek() constants
+SEEK_SET, SEEK_CUR, and SEEK_END are available via the C<:seek> tag.
+The chmod()/stat() S_IF* constants and S_IS* functions are available
+via the C<:mode> tag.
+
=item File::Compare
A bug that caused File::Find to lose track of the working directory
when pruning top-level directories has been fixed.
+File::Find now also supports several other options to control its
+behavior. It can follow symbolic links if the C<follow> option is
+specified. Enabling the C<no_chdir> option will make File::Find skip
+changing the current directory when walking directories. The C<untaint>
+flag can be useful when running with taint checks enabled.
+
+See L<File::Find>.
+
+=item File::Glob
+
+This extension implements BSD-style file globbing. By default,
+it will also be used for the internal implementation of the glob()
+operator. See L<File::Glob>.
+
=item File::Spec
New methods have been added to the File::Spec module: devnull() returns
=item Getopt::Long
-[TODO - Johan Vromans <jvromans@squirrel.nl>]
+Getopt::Long licensing has changed to allow the Perl Artistic License
+as well as the GPL. It used to be GPL only, which got in the way of
+non-GPL applications that wanted to use Getopt::Long.
+
+Getopt::Long encourages the use of Pod::Usage to produce help
+messages. For example:
+
+ use Getopt::Long;
+ use Pod::Usage;
+ my $man = 0;
+ my $help = 0;
+ GetOptions('help|?' => \$help, man => \$man) or pod2usage(2);
+ pod2usage(1) if $help;
+ pod2usage(-exitstatus => 0, -verbose => 2) if $man;
+
+ __END__
+
+ =head1 NAME
+
+ sample - Using GetOpt::Long and Pod::Usage
+
+ =head1 SYNOPSIS
+
+ sample [options] [file ...]
+
+ Options:
+ -help brief help message
+ -man full documentation
+
+ =head1 OPTIONS
+
+ =over 8
+
+ =item B<-help>
+
+ Print a brief help message and exits.
+
+ =item B<-man>
+
+ Prints the manual page and exits.
+
+ =back
+
+ =head1 DESCRIPTION
+
+ B<This program> will read the given input file(s) and do someting
+ useful with the contents thereof.
+
+ =cut
+
+See L<Pod::Usage> for details.
+
+A bug that prevented the non-option call-back E<lt>E<gt> from being
+specified as the first argument has been fixed.
+
+To specify the characters E<lt> and E<gt> as option starters, use
+E<gt>E<lt>. Note, however, that changing option starters is strongly
+deprecated.
=item IO
=item Math::BigInt
-The logical operations C<E<lt>E<lt>>, C<E<gt>E<gt>>, C<&>, C<|>,
+The bitwise operations C<E<lt>E<lt>>, C<E<gt>E<gt>>, C<&>, C<|>,
and C<~> are now supported on bigints.
=item Math::Complex
A little bit of radial trigonometry (cylindrical and spherical),
radial coordinate conversions, and the great circle distance were added.
-=item Pod::Parser
+=item Pod::Parser, Pod::InputObjects
+
+Pod::Parser is a base class for parsing and selecting sections of
+pod documentation from an input stream. This module takes care of
+identifying pod paragraphs and commands in the input and hands off the
+parsed paragraphs and commands to user-defined methods which are free
+to interpret or translate them as they see fit.
+
+Pod::InputObjects defines some input objects needed by Pod::Parser, and
+for advanced users of Pod::Parser that need more about a command besides
+its name and text.
+
+As of release 5.6 of Perl, Pod::Parser is now the officially sanctioned
+"base parser code" recommended for use by all pod2xxx translators.
+Pod::Text (pod2text) and Pod::Man (pod2man) have already been converted
+to use Pod::Parser and efforts to convert Pod::HTML (pod2html) are already
+underway. For any questions or comments about pod parsing and translating
+issues and utilities, please use the pod-people@perl.org mailing list.
-[TODO - Brad Appleton <bradapp@enteract.com>]
+For further information, please see L<Pod::Parser> and L<Pod::InputObjects>.
+
+=item Pod::Checker, podchecker
+
+This utility checks pod files for correct syntax, according to
+L<perlpod>. Obvious errors are flagged as such, while warnings are
+printed for mistakes that can be handled gracefully. The checklist is
+not complete yet. See L<Pod::Checker>.
+
+=item Pod::ParseUtils, Pod::Find
+
+These modules provide a set of gizmos that are useful mainly for pod
+translators. L<Pod::Find|Pod::Find> traverses directory structures and
+returns found pod files, along with their canonical names (like
+C<File::Spec::Unix>). L<Pod::ParseUtils|Pod::ParseUtils> contains
+B<Pod::List> (useful for storing pod list information), B<Pod::Hyperlink>
+(for parsing the contents of C<LE<gt>E<lt>> sequences) and B<Pod::Cache>
+(for caching information about pod files, e.g. link nodes).
+
+=item Pod::Select, podselect
+
+Pod::Select is a subclass of Pod::Parser which provides a function
+named "podselect()" to filter out user-specified sections of raw pod
+documentation from an input stream. podselect is a script that provides
+access to Pod::Select from other scripts to be used as a filter.
+See L<Pod::Select>.
+
+=item Pod::Usage, pod2usage
+
+Pod::Usage provides the function "pod2usage()" to print usage messages for
+a Perl script based on its embedded pod documentation. The pod2usage()
+function is generally useful to all script authors since it lets them
+write and maintain a single source (the pods) for documentation, thus
+removing the need to create and maintain redundant usage message text
+consisting of information already in the pods.
+
+There is also a pod2usage script which can be used from other kinds of
+scripts to print usage messages from pods (even for non-Perl scripts
+with pods embedded in comments).
+
+For details and examples, please see L<Pod::Usage>.
=item Pod::Text and Pod::Man
happens to be read from the database in a single FETCH() has been
fixed.
+=item Sys::Syslog
+
+Sys::Syslog now uses XSUBs to access facilities from syslog.h so it
+no longer requires syslog.ph to exist.
+
+=item Sys::Hostname
+
+Sys::Hostname now uses XSUBs to call the C library's gethostname() or
+uname() if they exist.
+
=item Time::Local
The timelocal() and timegm() functions used to silently return bogus
-results when the date exceeded the machine's integer range. They
+results when the date fell outside the machine's integer range. They
now consistently croak() if the date falls in an unsupported range.
=item Win32
The new Win32::GetFullPathName(FILENAME) returns the full absolute
pathname for FILENAME in scalar context. In list context it returns
a two-element list containing the fully qualified directory name and
-the filename.
+the filename. See L<Win32>.
=item DBM Filters
=head2 Pragmata
-C<use attrs> is now obsolescent, and is only provided for
+C<use attrs> is now obsolete, and is only provided for
backward-compatibility. It's been replaced by the C<sub : attributes>
syntax. See L<perlsub/"Subroutine Attributes"> and L<attributes>.
C<use utf8> to enable UTF-8 and Unicode support.
-C<use caller 'encoding'> allows modules to inherit pragmatic attributes
-from the caller's context. C<encoding> is currently the only supported
-attribute.
-
Lexical warnings pragma, C<use warnings;>, to control optional warnings.
See L<perllexwarn>.
=over 4
+=item perlapi.pod
+
+The official list of public Perl API functions.
+
=item perlcompile.pod
An introduction to using the Perl Compiler suite.
+=item perlfilter.pod
+
+An introduction to writing Perl source filters.
+
=item perlhack.pod
Some guidelines for hacking the Perl source code.
+=item perlintern.pod
+
+A list of internal functions in the Perl source code.
+(List is currently empty.)
+
=item perlopentut.pod
A tutorial on using open() effectively.
A tutorial on managing class data for object modules.
+=item perlunicode.pod
+
+An introduction to Unicode support features in Perl.
+
=back
-=head1 New Diagnostics
+=head1 New or Changed Diagnostics
=over 4
+=item "%s" variable %s masks earlier declaration in same %s
+
+(W) A "my" or "our" variable has been redeclared in the current scope or statement,
+effectively eliminating all access to the previous instance. This is almost
+always a typographical error. Note that the earlier variable will still exist
+until the end of the scope or until all closure referents to it are
+destroyed.
+
=item "my sub" not yet implemented
(F) Lexically scoped subroutines are not yet implemented. Don't try that
yet.
+=item "our" variable %s redeclared
+
+(W) You seem to have already declared the same global once before in the
+current lexical scope.
+
=item '!' allowed only after types %s
(F) The '!' is allowed in pack() and unpack() only after certain types.
=item / must be followed by a*, A* or Z*
-(F) You had an pack template indicating a counted-length string,
+(F) You had a pack template indicating a counted-length string,
Currently the only things that can have their length counted are a*, A* or Z*.
See L<perlfunc/pack>.
but this did not follow some numeric unpack specification.
See L<perlfunc/pack>.
-=item Repeat count in pack overflows
-
-(F) You can't specify a repeat count so large that it overflows
-your signed integers. See L<perlfunc/pack>.
-
-=item Repeat count in unpack overflows
-
-(F) You can't specify a repeat count so large that it overflows
-your signed integers. See L<perlfunc/unpack>.
-
=item /%s/: Unrecognized escape \\%c passed through
(W) You used a backslash-character combination which is not recognized
by Perl. This combination appears in an interpolated variable or a
-C<'>-delimited regular expression.
+C<'>-delimited regular expression. The character was understood literally.
+
+=item /%s/: Unrecognized escape \\%c in character class passed through
+
+(W) You used a backslash-character combination which is not recognized
+by Perl inside character classes. The character was understood literally.
=item /%s/ should probably be written as "%s"
(W) You have used a pattern where Perl expected to find a string,
-like in the first argument to C<join>. Perl will treat the true
+as in the first argument to C<join>. Perl will treat the true
or false result of matching the pattern against $_ as the string,
which is probably not what you had in mind.
if you are certain that you're calling the function correctly, you may put
an ampersand before the name to avoid the warning. See L<perlsub>.
+=item %s argument is not a HASH or ARRAY element
+
+(F) The argument to exists() must be a hash or array element, such as:
+
+ $foo{$bar}
+ $ref->[12]->["susie"]
+
+=item %s argument is not a HASH or ARRAY element or slice
+
+(F) The argument to delete() must be either a hash or array element, such as:
+
+ $foo{$bar}
+ $ref->[12]->["susie"]
+
+or a hash or array slice, such as:
+
+ @foo[$bar, $baz, $xyzzy]
+ @{$ref->[12]}{"susie", "queue"}
+
+=item %s argument is not a subroutine name
+
+(F) The argument to exists() for C<exists &sub> must be a subroutine
+name, and not a subroutine call. C<exists &sub()> will generate this error.
+
=item %s package attribute may clash with future reserved word: %s
(W) A lowercase attribute name was used that had a package-specific handler.
malloc()ed in the first place. Mandatory, but can be disabled by
setting environment variable C<PERL_BADFREE> to 1.
+=item Bareword found in conditional
+
+(W) The compiler found a bareword where it expected a conditional,
+which often indicates that an || or && was parsed as part of the
+last argument of the previous construct, for example:
+
+ open FOO || die;
+
+It may also indicate a misspelled constant that has been interpreted
+as a bareword:
+
+ use constant TYPO => 1;
+ if (TYOP) { print "foo" }
+
+The C<strict> pragma is useful in avoiding such errors.
+
=item Binary number > 0b11111111111111111111111111111111 non-portable
(W) The binary number you specified is larger than 2**32-1
(P) For some reason you can't check the filesystem of the script for nosuid.
+=item Can't declare class for non-scalar %s in "%s"
+
+(S) Currently, only scalar variables can declared with a specific class
+qualifier in a "my" or "our" declaration. The semantics may be extended
+for other types of variables in future.
+
+=item Can't declare %s in "%s"
+
+(F) Only scalar, array, and hash variables may be declared as "my" or
+"our" variables. They must have ordinary identifiers as names.
+
+=item Can't ignore signal CHLD, forcing to default
+
+(W) Perl has detected that it is being run with the SIGCHLD signal
+(sometimes known as SIGCLD) disabled. Since disabling this signal
+will interfere with proper determination of exit status of child
+processes, Perl has reset the signal to its default value.
+This situation typically indicates that the parent program under
+which Perl may be running (e.g. cron) is being very careless.
+
=item Can't modify non-lvalue subroutine call
-(F) Subroutines used in lvalue context should be marked as such, see
-L<perlsub/"Lvalue subroutines">.
+(F) Subroutines meant to be used in lvalue context should be declared as
+
such, see L<perlsub/"Lvalue subroutines">.
=item Can't read CRTL environ
=item Character class [:%s:] unknown
(F) The class in the character class [: :] syntax is unknown.
+See L<perlre>.
=item Character class syntax [%s] belongs inside character classes
(W) The character class constructs [: :], [= =], and [. .] go
I<inside> character classes, the [] are part of the construct,
-for example: /[012[:alpha:]345]/. Note that the last two constructs
-are not currently implemented, they are placeholders for future extensions.
+for example: /[012[:alpha:]345]/. Note that [= =] and [. .]
+are not currently implemented; they are simply placeholders for
+future extensions.
=item Constant is not %s reference
See Server error.
+=item Did you mean "local" instead of "our"?
+
+(W) Remember that "our" does not localize the declared global variable.
+You have declared it again in the same lexical scope, which seems superfluous.
+
=item Document contains no data
See Server error.
(F) While under the C<use filetest> pragma, switching the real and
effective uids or gids failed.
+=item false [] range "%s" in regexp
+
+(W) A character class range must start and end at a literal character, not
+another character class like C<\d> or C<[:alpha:]>. The "-" in your false
+range is interpreted as a literal "-". Consider quoting the "-", "\-".
+See L<perlre>.
+
=item Filehandle %s opened only for output
(W) You tried to read from a filehandle opened only for writing. If you
-intended it to be a read-write filehandle, you needed to open it with
+intended it to be a read/write filehandle, you needed to open it with
"+E<lt>" or "+E<gt>" or "+E<gt>E<gt>" instead of with "E<lt>" or nothing. If
you intended only to read from the file, use "E<lt>". See
L<perlfunc/open>.
+=item flock() on closed filehandle %s
+
+(W) The filehandle you're attempting to flock() got itself closed some
+time before now. Check your logic flow. flock() operates on filehandles.
+Are you attempting to call flock() on a dirhandle by the same name?
+
+=item Global symbol "%s" requires explicit package name
+
+(F) You've said "use strict vars", which indicates that all variables
+must either be lexically scoped (using "my"), declared beforehand using
+"our", or explicitly qualified to say which package the global variable
+is in (using "::").
+
=item Hexadecimal number > 0xffffffff non-portable
(W) The hexadecimal number you specified is larger than 2**32-1
=item Illegal binary digit %s
-(F) You used a digit other than 0 and 1 in a binary number.
+(F) You used a digit other than 0 or 1 in a binary number.
=item Illegal binary digit %s ignored
=item Integer overflow in %s number
(W) The hexadecimal, octal or binary number you have specified either
-as a literal in your code or as a scalar is too big for your
+as a literal or as an argument to hex() or oct() is too big for your
architecture, and has been converted to a floating point number. On a
32-bit architecture the largest hexadecimal, octal or binary number
representable without overflow is 0xFFFFFFFF, 037777777777, or
The indicated attributes for a subroutine or variable were not recognized
by Perl or by a user-supplied handler. See L<attributes>.
+=item invalid [] range "%s" in regexp
+
+The offending range is now explicitly displayed.
+
=item Invalid separator character %s in attribute list
-(F) Something other than a comma or whitespace was seen between the
+(F) Something other than a colon or whitespace was seen between the
elements of an attribute list. If the previous attribute
had a parenthesised parameter list, perhaps that list was terminated
too soon. See L<attributes>.
=item Invalid separator character %s in subroutine attribute list
-(F) Something other than a comma or whitespace was seen between the
+(F) Something other than a colon or whitespace was seen between the
elements of a subroutine attribute list. If the previous attribute
had a parenthesised parameter list, perhaps that list was terminated
too soon.
(F) The reserved syntax for lexically scoped subroutines requires that they
have a name with which they can be found.
+=item No %s specified for -%c
+
+(F) The indicated command line switch needs a mandatory argument, but
+you haven't specified one.
+
+=item No package name allowed for variable %s in "our"
+
+(F) Fully qualified variable names are not allowed in "our" declarations,
+because that doesn't make much sense under existing semantics. Such
+syntax is reserved for future extensions.
+
+=item No space allowed after -%c
+
+(F) The argument to the indicated command line switch must follow immediately
+after the switch, without intervening spaces.
+
=item no UTC offset information; assuming local time is UTC
(S) A warning peculiar to VMS. Perl was unable to find the local
(P) Failed an internal consistency check while trying to reset all weak
references to an object.
+=item Parentheses missing around "%s" list
+
+(W) You said something like
+
+ my $foo, $bar = @_;
+
+when you meant
+
+ my ($foo, $bar) = @_;
+
+Remember that "my", "our" and "local" bind closer than comma.
+
=item Possible Y2K bug: %s
(W) You are concatenating the number 19 with another number, which
See Server error.
+=item Repeat count in pack overflows
+
+(F) You can't specify a repeat count so large that it overflows
+your signed integers. See L<perlfunc/pack>.
+
+=item Repeat count in unpack overflows
+
+(F) You can't specify a repeat count so large that it overflows
+your signed integers. See L<perlfunc/unpack>.
+
=item realloc() of freed memory ignored
(S) An internal routine called realloc() on something that had already
(F) While under the C<use filetest> pragma, we cannot switch the
real and effective uids or gids.
-=item This Perl can't reset CRTL eviron elements (%s)
+=item This Perl can't reset CRTL environ elements (%s)
=item This Perl can't set CRTL environ elements (%s=%s)
=item Unknown open() mode '%s'
-(F) The second argument of 3-arguments open is not one from the list
-of C<L<lt>>, C<L<gt>>, C<E<gt>E<gt>>, C<+L<lt>>, C<+L<gt>>,
-C<+E<gt>E<gt>>, C<-|>, C<|-> of possible open() modes.
+(F) The second argument of 3-argument open() is not among the list
+of valid modes: C<E<lt>>, C<E<gt>>, C<E<gt>E<gt>>, C<+E<lt>>,
+C<+E<gt>>, C<+E<gt>E<gt>>, C<-|>, C<|E<45>>.
=item Unknown process %x sent message to prime_env_iter: %s
=item Unrecognized escape \\%c passed through
(W) You used a backslash-character combination which is not recognized
-by Perl.
+by Perl. The character was understood literally.
=item Unterminated attribute parameter in attribute list
might directly modify logical name tables and introduce nonstandard names,
or it may indicate that a logical name table has been corrupted.
+=item Probable precedence problem on %s
+
+(W) The compiler found a bareword where it expected a conditional,
+which often indicates that an || or && was parsed as part of the
+last argument of the previous construct, for example:
+
+ open FOO || die;
+
=item regexp too big
(F) The current implementation of regular expressions uses shorts as
=head1 BUGS
-If you find what you think is a bug, you might check the headers of
+If you find what you think is a bug, you might check the
articles recently posted to the comp.lang.perl.misc newsgroup.
There may also be information at http://www.perl.com/perl/, the Perl
Home Page.
https://perl5.git.perl.org / perl5.git / blobdiff