Thanks to all, here's a new version of perl594delta, close to the
definitive one. Speak up if I forgot something or someone. 5.9.4 is
very close now!
NAME
perldelta - what is new for perl v5.9.4
DESCRIPTIN
This document describes differences between the 5.9.3 and the 5.9.4
developement releases. See perl590delta, perl591delta, perl592delta and
perl593delta for the differences between 5.8.0 and 5.9.3.
Incompatible Changes
chdir F
A bareword argument to chdir() is now recognized as a file handle.
Earlier releases interpreted the bareword as a directory name. (Gisle
Aas)
Handling of pmc files
An old feature of perl was that before "require" or "use" look for a
file with a .pm extension, they will first look for a similar filename
with a .pmc extension. If this file is found, it will be loaded in place
of any potentially existing file ending in a .pm extension.
Previously, .pmc files were loaded only if more recent than the matching
.pm file. Starting with 5.9.4, they'll be always loaded if they exist.
(This trick is used by Pugs.)
@- and @+ in patterns
The special arrays "@-" and "@+" are no longer interpolated in regular
expressions. (Sadahiro Tomoyuki)
$AUTLAD can now be tainted
If you call a subroutine by a tainted name, and if it defers to an
AUTLAD function, then $AUTLAD will be (correctly) tainted. (Rick
Delaney)
Core Enhancements
state() variables
A new class of variables has been introduced. State variables are
similar to "my" variables, but are declared with the "state" keyword in
place of "my". They're visible only in their lexical scope, but their
value in persistent: unlike "my" variables, they're not undefined at
scope entry, and retain their previous value. (Rafael Garcia-Suarez)
To use state variables, one needs to enable them by using
use feature "state";
or by using the "-E" command-line switch in one-liners.
See "Persistent variables via state()" in perlsub.
UNIVERSAL::DES()
The "UNIVERSAL" class has a new method, "DES()". It has been added to
solve semantic problems with the "isa()" method. "isa()" checks for
inheritance, while "DES()" has been designed to be overriden when
module authors use other types of relations between classes (in addition
to inheritance). (chromatic)
See "$obj->DES( RLE )" in UNIVERSAL.
Exceptions in constant folding
The constant folding routine is now wrapped in an exception handler, and
if folding throws an exception (such as attempting to evaluate 0/0),
perl now retains the current optree, rather than aborting the whole
program. (Nicholas Clark, Dave Mitchell)
Source filters in @INC
It's possible to enhance the mechanism of subroutine hooks in @INC by
adding a source filter on top of the filehandle opened and returned by
the hook. This feature was planned a long time ago, but wasn't quite
working until now. See "require" in perlfunc for details. (Nicholas
Clark)
MAD
MAD, which stands for *Misc Attribute Decoration*, is a
still-in-development work leading to a Perl 5 to Perl 6 convertor. To
enable it, it's necessary to pass the argument "-Dmad" to Configure. The
obtained perl isn't binary compatible with a regular perl 5.9.4, and has
space and speed penalties; moreover not all regression tests still pass
with it. (Larry Wall, Nicholas Clark)
Modules and Pragmata
* "encoding::warnings" is now a lexical pragma. (Although on older
perls, which don't have support for lexical pragmas, it keeps its
global behaviour.) (Audrey Tang)
* "threads" is now a dual-life module, also available on CPAN. It has
been expanded in many ways. A kill() method is available for thread
signalling. can get thread status, or the list of running or
joinable threads.
A new "threads->exit()" method is used to exit from the application
(this is the default for the main thread) or from the current thread
only (this is the default for all other threads). the other hand,
the exit() built-in now always causes the whole application to
terminate. (Jerry D. Hedden)
New Core Modules
* "Hash::Util::FieldHash", by Anno Siegel, has been added. This module
provides support for *field hashes*: hashes that maintain an
association of a reference with a value, in a thread-safe
garbage-collected way.
* "Module::Build", by Ken Williams, has been added. It's an
alternative to "ExtUtils::MakeMaker" to build and install perl
modules.
* "Module::Load", by Jos Boumans, has been added. It provides a single
interface to load Perl modules and .pl files.
* "Module::Loaded", by Jos Boumans, has been added. It's used to mark
modules as loaded or unloaded.
* "Package::Constants", by Jos Boumans, has been added. It's a simple
helper to list all constants declared in a given package.
* "Win32API::File", by Tye McQueen, has been added (for Windows
builds). This module provides low-level access to Win32 system API
calls for files/dirs.
Utility Changes
config_data
"config_data" is a new utility that comes with "Module::Build". It
provides a command-line interface to the configuration of Perl modules
that use Module::Build's framework of configurability (that is,
*::ConfigData modules, that contain local configuration information for
their parent modules.)
Documentation
New manpage, perlpragma
The perlpragma manpage documents how to write one's own lexical pragmas
in pure Perl (something that is possible only starting with 5.9.4).
New manpage, perlreguts
The perlreguts manpage, due to Yves , describes internals of the
Perl regular expression engine.
New manpage, perlunitut
The perlunitut manpage is an tutorial for programming with Unicode and
string encodings in Perl, due to Juerd Waalboer.
Performance Enhancements
Memory optimisations
Several internal data structures (typeglobs, GVs, CVs, formats) have
been restructured to use less memory. (Nicholas Clark)
UTF-8 cache optimisation
The UTF-8 caching code is now more efficient, and used more often.
(Nicholas Clark)
Regular expressions
Engine de-recursiveized
The regular expression engine is no longer recursive, meaning that
patterns that used to overflow the stack will either die with useful
explanations, or run to completion, which, since they were able to
blow the stack before, will likely take a very long time to happen.
If you were experiencing the occasional stack overflow (or segfault)
and upgrade to discover that now perl apparently hangs instead, look
for a degenerate regex. (Dave Mitchell)
Single char char-classes treated as literals
Classes of a single character are now treated the same as if the
character had been used as a literal, meaning that code that uses
char-classes as an escaping mechanism will see a speedup. (Yves
)
Trie optimisation of literal string alternations
Alternations, where possible, are optimised into more efficient
matching structures. String literal alternations are merged into a
trie and are matched simultaneously. This means that instead of (N)
time for matching N alternations at a given point the new code
performs in (1) time. (Yves )
Note: Much code exists that works around perl's historic poor
performance on alternations. the tricks used to do so will
disable the new optimisations. Hopefully the utility modules used
for this purpose will be educated about these new optimisations by
the time 5.10 is released.
Aho-Corasick start-point optimisation
When a pattern starts with a trie-able alternation and there aren't
better optimisations available the regex engine will use
Aho-Corasick matching to find the start point. (Yves )
Installation and Configuration Improvements
Relocatable installations
There is now Configure support for creating a relocatable perl tree. If
you Configure with "-Duserelocatableinc", then the paths in @INC (and
everything else in %Config) can be optionally located via the path of
the perl executable.
That means that, if the string "/" is found at the start of any path,
it's substituted with the directory of $^X. So, the relocation can be
configured on a per-directory basis, although the default with
"-Duserelocatableinc" is that everything is relocated. The initial
install is done to the original configured prefix.
Ports
Many improvements have been made towards making Perl work correctly on
z/S.
Perl has been reported to work on DragonFlyBSD.
Compilation improvements
All ppport.h files in the XS modules bundled with perl are now
autogenerated at build time. (Marcus Holland-Moritz)
New probes
The configuration process now detects whether strlcat() and strlcpy()
are available. When they are not available, perl's own version is used
(from Russ Allbery's public domain implementation). Various places in
the perl interpreter now uses them. (Steve Peters)
Selected Bug Fixes
PERL5SHELL and tainting
Windows, PERL5SHELL is now checked for taintedness. (Rafael
Garcia-Suarez)
Using *FILE{I}
"stat()" and "-X" filetests now treat *FILE{I} filehandles like *FILE
filehandles. (Steve Peters)
and reblessing
now works when references are reblessed into another class.
Internally, this has been implemented by moving the flag for
"overloading" from the reference to the referent, which logically is
where it should always have been. (Nicholas Clark)
and UTF-8
A few bugs related to UTF-8 handling with objects that have
stringification overloaded have been fixed. (Nicholas Clark)
New or Changed Diagnostics
State variable %s will be reinitialized
can assign initial values to state variables, but not when
they're declared as a sub-part of a list assignment. See perldiag.
Changed Internals
A new file, mathoms.c, contains functions that aren't used anymore in
the perl core, but that remain around because modules out there might
still use them. They come from a factorization effort: for example, many
PP functions are now shared for several ops.
The implementation of the special variables $^H and %^H has changed, to
allow implementing lexical pragmas in pure perl.
Known Problems
warning test (number 263 in lib/warnings.t) fails under UTF-8
locales.
Bytecode tests fails under several platforms. We are considering
removing support for byteloader and compiler before the 5.10.0 release.
Platform-specific Problems
The test ext/Socket/t/socketpair.t crashes after completing all tests
successfully when built with USE_ITHREADS and PERL_IMPLICIT_SYS on
Win32.
Reporting Bugs
If you find what you think is a bug, you might check the articles
recently posted to the comp.lang.perl.misc newsgroup and the perl bug
database at http://rt.perl.org/rt3/ . There may also be information at
http://www.perl.org/ , the Perl Home Page.
If you believe you have an unreported bug, please run the perlbug
program included with your release. Be sure to trim your bug down to a
tiny but sufficient test case. Your bug report, along with the output of
"perl -V", will be sent off to perlbug (AT) perl (DOT) org to be analysed by the
Perl porting team.
SEE ALS
The Changes file for exhaustive details on what changed.
The INSTALL file for how to build Perl.
The README file for general stuff.
The Artistic and Copying files for copyright information.

Mon, Aug 14, 2006 at 11:59:55PM +0200, Rafael Garcia-Suarez wrote:

Just some nits.

Core Enhancements
state() variables
A new class of variables has been introduced. State variables are
similar to "my" variables, but are declared with the "state" keyword in
place of "my". They're visible only in their lexical scope, but their
value in persistent: unlike "my" variables, they're not undefined at

s/in/is/

scope entry, and retain their previous value. (Rafael Garcia-Suarez)

s/and/but/ (maybe)

Installation and Configuration Improvements

New probes
The configuration process now detects whether strlcat() and strlcpy()
are available. When they are not available, perl's own version is used
(from Russ Allbery's public domain implementation). Various places in
the perl interpreter now uses them. (Steve Peters)

s/uses/use/

Known Problems
warning test (number 263 in lib/warnings.t) fails under UTF-8
locales.

Bytecode tests fails under several platforms. We are considering
removing support for byteloader and compiler before the 5.10.0 release.

s/fails/fail/

Ronald

Mon, Aug 14, 2006 at 11:59:55PM +0200, Rafael Garcia-Suarez wrote:

A few nits

Steve Peters
steve (AT) fisharerojo (DOT) org

Thanks to all, here's a new version of perl594delta, close to the
definitive one. Speak up if I forgot something or someone. 5.9.4 is
very close now!

NAME
perldelta - what is new for perl v5.9.4

DESCRIPTIN
This document describes differences between the 5.9.3 and the 5.9.4
developement releases. See perl590delta, perl591delta, perl592delta and

s/developement/development/

perl593delta for the differences between 5.8.0 and 5.9.3.

<snip

UNIVERSAL::DES()
The "UNIVERSAL" class has a new method, "DES()". It has been added to
solve semantic problems with the "isa()" method. "isa()" checks for
inheritance, while "DES()" has been designed to be overriden when

s/overriden/overridden/

module authors use other types of relations between classes (in addition
to inheritance). (chromatic)

See "$obj->DES( RLE )" in UNIVERSAL.

Exceptions in constant folding
The constant folding routine is now wrapped in an exception handler, and
if folding throws an exception (such as attempting to evaluate 0/0),
perl now retains the current optree, rather than aborting the whole
program. (Nicholas Clark, Dave Mitchell)

Source filters in @INC
It's possible to enhance the mechanism of subroutine hooks in @INC by
adding a source filter on top of the filehandle opened and returned by
the hook. This feature was planned a long time ago, but wasn't quite
working until now. See "require" in perlfunc for details. (Nicholas
Clark)

MAD
MAD, which stands for *Misc Attribute Decoration*, is a
still-in-development work leading to a Perl 5 to Perl 6 convertor. To

s/convertor/converter/

enable it, it's necessary to pass the argument "-Dmad" to Configure. The
obtained perl isn't binary compatible with a regular perl 5.9.4, and has
space and speed penalties; moreover not all regression tests still pass
with it. (Larry Wall, Nicholas Clark)

Modules and Pragmata
* "encoding::warnings" is now a lexical pragma. (Although on older
perls, which don't have support for lexical pragmas, it keeps its
global behaviour.) (Audrey Tang)

* "threads" is now a dual-life module, also available on CPAN. It has
been expanded in many ways. A kill() method is available for thread
signalling. can get thread status, or the list of running or

s/signalling/signaling/

joinable threads.

<snip>

Utility Changes
config_data
"config_data" is a new utility that comes with "Module::Build". It
provides a command-line interface to the configuration of Perl modules
that use Module::Build's framework of configurability (that is,
*::ConfigData modules, that contain local configuration information for

s/moudles, that/modules that/

<snip>

Changed Internals
A new file, mathoms.c, contains functions that aren't used anymore in
the perl core, but that remain around because modules out there might

s/that//

15/08/06, Dave Mitchell <davem (AT) iabyn (DOT) comwrote:
Sorry, I've been a bit busy recently. How about under Selected Bug Fixes:

eval memory leaks fixed

I added that.

Which also reminds me: one of those eval fixes has a serious flaw on
ithreads builds: when freeing ops on the parse stack, the freed op may
have a TARG, which points to a pad, but when freeing, PL_curpad may not
point to the pad associated with that op, leading to segfaults.

If I don't come up with a fix for this before 5.9.4 is ready for release
(which seems pretty certain), you may want to back out change #28319.

I backed it out as change #28720.

14.08.2006, at 23:59, Rafael Garcia-Suarez wrote:

Thanks to all, here's a new version of perl594delta, close to the
definitive one. Speak up if I forgot something or someone. 5.9.4 is
very close now!

Yes, please. I'd like to mention "inside-out classes" where
Hash::Util::FieldHash is announced. From the abstract properties
it is hard to see what a field hash is good for.

Anno

15/08/06, Anno Siegel <anno4000 (AT) mailbox (DOT) tu-berlin.dewrote:
Yes, please. I'd like to mention "inside-out classes" where
Hash::Util::FieldHash is announced. From the abstract properties
it is hard to see what a field hash is good for.

Aargh!! I knew I forgot something. Too late (but will be mentioned later.)

15.08.2006, at 18:57, Rafael Garcia-Suarez wrote:

15/08/06, Anno Siegel <anno4000 (AT) mailbox (DOT) tu-berlin.dewrote:
>Yes, please. I'd like to mention "inside-out classes" where
>Hash::Util::FieldHash is announced. From the abstract properties
>it is hard to see what a field hash is good for.
>
Aargh!! I knew I forgot something. Too late (but will be mentioned
later.)

I see. Thanks for the thought anyway :)

Anno

Incompatible Changes
chdir F
A bareword argument to chdir() is now recognized as a file handle.
Earlier releases interpreted the bareword as a directory name. (Gisle
Aas)

not a directory handle? A directory handle makes sense, you could change
into the directory that you have a handle to. How a file handle would work
there is not obvious to me. Does the program change working directory
to the directory with the name found by calling readline on the argument?
The program can't change directory to the directory in which the file lives,
because that would be ambiguous.

15/08/06, David Nicol <davidnicol (AT) gmail (DOT) comwrote:
not a directory handle? A directory handle makes sense, you could change
into the directory that you have a handle to. How a file handle would work
there is not obvious to me. Does the program change working directory
to the directory with the name found by calling readline on the argument?
The program can't change directory to the directory in which the file lives,
because that would be ambiguous.

You could already use chdir($fh), and that invokes fchdir(2) (on
systems that have it.)
See the previous perldeltas. This change is only syntactic.