DESCRIPTION

This document lists the current and past experimental features in the perl core. Although all of these are documented with their appropriate topics, this succinct listing gives you an overview and basic facts about their status.

So far we've merely tried to find and list the experimental features and infer their inception, versions, etc. There's a lot of speculation here.

Current experiments

"our" can now have an experimental optional attribute "unique"

Introduced in Perl 5.8.0

Deprecated in Perl 5.10.0

The ticket for this feature is [perl #119313] <https://rt.perl.org/rt3/Ticket/Display.html?id=119313>.

Smart match ("~~")

Introduced in Perl 5.10.0

Modified in Perl 5.10.1, 5.12.0

Using this feature triggers warnings in the category "experimental::smartmatch".

The ticket for this feature is [perl #119317] <https://rt.perl.org/rt3/Ticket/Display.html?id=119317>.

Lexical $_

Introduced in Perl 5.10.0

Using this feature triggers warnings in the category "experimental::lexical_topic".

The ticket for this feature is [perl #119315] <https://rt.perl.org/rt3/Ticket/Display.html?id=119315>.

Pluggable keywords

The ticket for this feature is [perl #119455] <https://rt.perl.org/rt3/Ticket/Display.html?id=119455>.

See ``PL_keyword_plugin'' in perlapi for the mechanism.

Introduced in: Perl 5.11.2

Array and hash container functions accept references

Introduced in Perl 5.14.0

The ticket for this feature is [perl #119437] <https://rt.perl.org/rt3/Ticket/Display.html?id=119437>.

Lexical subroutines

Introduced in: Perl 5.18

See also: ``Lexical Subroutines'' in perlsub

Using this feature triggers warnings in the category "experimental::lexical_subs".

The ticket for this feature is [perl #120085] <https://rt.perl.org/rt3/Ticket/Display.html?id=120085>.

Regular Expression Set Operations

Introduced in: Perl 5.18

The ticket for this feature is [perl #119451] <https://rt.perl.org/rt3/Ticket/Display.html?id=119451>.

See also: ``Extended Bracketed Character Classes'' in perlrecharclass

Using this feature triggers warnings in the category "experimental::regex_sets".

Subroutine signatures

Introduced in Perl 5.20.0

Using this feature triggers warnings in the category "experimental::signatures".

The ticket for this feature is [perl #121481] <https://rt.perl.org/Ticket/Display.html?id=121481>.

Postfix dereference syntax

Introduced in Perl 5.20.0

Using this feature triggers warnings in the category "experimental::postderef".

The ticket for this feature is [perl #120162] <https://rt.perl.org:443/rt3/Ticket/Display.html?id=120162>.

Aliasing via reference

Introduced in Perl 5.22.0

Using this feature triggers warnings in the category "experimental::refaliasing".

The ticket for this feature is [perl #122947] <https://rt.perl.org/rt3/Ticket/Display.html?id=122947>.

See also: ``Assigning to References'' in perlref

The "const" attribute

Introduced in Perl 5.22.0

Using this feature triggers warnings in the category "experimental::const_attr".

The ticket for this feature is [perl #123630] <https://rt.perl.org/rt3/Ticket/Display.html?id=123630>.

See also: ``Constant Functions'' in perlsub

use re 'strict';

Introduced in Perl 5.22.0

Using this feature triggers warnings in the category "experimental::re_strict".

See ``'strict' mode'' in re

String- and number-specific bitwise operators

Introduced in: Perl 5.22.0

See also: ``Bitwise String Operators'' in perlop

Using this feature triggers warnings in the category "experimental::bitwise".

The ticket for this feature is [perl #123707] <https://rt.perl.org/rt3/Ticket/Display.html?id=123707>.

The <:win32> IO pseudolayer

The ticket for this feature is [perl #119453] <https://rt.perl.org/rt3/Ticket/Display.html?id=119453>.

See also perlrun

There is an "installhtml" target in the Makefile.

The ticket for this feature is [perl #116487] <https://rt.perl.org/rt3/Ticket/Display.html?id=116487>.

Unicode in Perl on EBCDIC

Accepted features

These features were so wildly successful and played so well with others that we decided to remove their experimental status and admit them as full, stable features in the world of Perl, lavishing all the benefits and luxuries thereof. They are also awarded +5 Stability and +3 Charisma.

64-bit support

Introduced in Perl 5.005

die accepts a reference

Introduced in Perl 5.005

DB module

Introduced in Perl 5.6.0

See also perldebug, perldebtut

Weak references

Introduced in Perl 5.6.0

Internal file glob

Introduced in Perl 5.6.0

fork() emulation

Introduced in Perl 5.6.1

See also perlfork

-Dusemultiplicity -Duseithreads

Introduced in Perl 5.6.0

Accepted in Perl 5.8.0

Support for long doubles

Introduced in Perl 5.6.0

Accepted in Perl 5.8.1

The "\N" regex character class

The "\N" character class, not to be confused with the named character sequence "\N{NAME}", denotes any non-newline character in a regular expression.

Introduced in Perl 5.12

Exact version of acceptance unclear, but no later than Perl 5.18.

"(?{code})" and "(??{ code })"

Introduced in Perl 5.6.0

Accepted in Perl 5.20.0

See also perlre

Linux abstract Unix domain sockets

Introduced in Perl 5.9.2

Accepted before Perl 5.20.0. The Socket library is now primarily maintained on CPAN, rather than in the perl core.

See also Socket

Lvalue subroutines

Introduced in Perl 5.6.0

Accepted in Perl 5.20.0

See also perlsub

Backtracking control verbs

"(*ACCEPT)"

Introduced in: Perl 5.10

Accepted in Perl 5.20.0

The <:pop> IO pseudolayer

See also perlrun

Accepted in Perl 5.20.0

"\s" in regexp matches vertical tab

Accepted in Perl 5.22.0

Removed features

These features are no longer considered experimental and their functionality has disappeared. It's your own fault if you wrote production programs using these features after we explicitly told you not to (see perlpolicy).

5.005-style threading

Introduced in Perl 5.005

Removed in Perl 5.10

perlcc

Introduced in Perl 5.005

Moved from Perl 5.9.0 to CPAN

The pseudo-hash data type

Introduced in Perl 5.6.0

Removed in Perl 5.9.0

GetOpt::Long Options can now take multiple values at once (experimental)

"Getopt::Long" upgraded to version 2.35

Removed in Perl 5.8.8

Assertions

The "-A" command line switch

Introduced in Perl 5.9.0

Removed in Perl 5.9.5

Test::Harness::Straps

Moved from Perl 5.10.1 to CPAN

"legacy"

The experimental "legacy" pragma was swallowed by the "feature" pragma.

Introduced in: 5.11.2

Removed in: 5.11.3

AUTHORS

brian d foy "<[email protected]>"

Sebastien Aperghis-Tramoni "<[email protected]>"

COPYRIGHT

Copyright 2010, brian d foy "<[email protected]>"

LICENSE

You can use and redistribute this document under the same terms as Perl itself.