perlexperiment - A listing of experimental features in Perl
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.
Introduced in Perl 5.11.2
See "PL_keyword_plugin" in perlapi for the mechanism.
The ticket for this experiment is [perl #13199].
Introduced in Perl 5.22.0
Using this feature triggers warnings in the category experimental::refaliasing.
The ticket for this experiment is [perl #14150].
See also: "Assigning to References" in perlref
Introduced in Perl 5.22.0
Using this feature triggers warnings in the category experimental::re_strict.
The ticket for this experiment is [perl #18755]
Introduced in Perl 5.26.0
Using this feature triggers warnings in the category experimental::declared_refs.
The ticket for this experiment is [perl #15458].
installhtml target in the Makefile.The ticket for this experiment is [perl #12726].
Introduced in Perl 5.30.0.
Variability of up to 255 characters is handled.
Using this feature triggers warnings in the category experimental::vlb.
The ticket for this experiment is [perl #18756].
See also: "(*positive_lookbehind:pattern)" in perlre and "(*negative_lookbehind:pattern)" in perlre
Introduced in Perl 5.30.0.
This feature is part of an interface intended for internal and experimental use by the perl5 developers. You are unlikely to encounter it in the wild.
Using this feature triggers warnings in the category experimental::private_use.
The ticket for this experiment is [perl #18758].
Introduced in Perl 5.30.0.
This feature allows regular expression matching against Unicode character properties to be expressed more concisely.
Using this feature triggers warnings in the category experimental::uniprop_wildcards.
The ticket for this experiment is [perl #18759].
Introduced in Perl 5.34.0.
Using the optional finally block part of this feature triggers warnings in the category experimental::try.
The ticket for this experiment is [perl #18760]
@_ within subroutine signaturesIntroduced in Perl 5.36.0 as part of a reduction in the scope of experimental subroutine signatures.
Using the default arguments array (@_) within a subroutine that uses signatures will emit a warning in the category experimental::args_array_with_signatures. This includes @_ directly, elements of it such as $_[$index], or situations where the default arguments array is accessed implicitly such as shift or pop without arguments.
Introduced in Perl 5.36.0.
Using certain functions of this feature triggers warnings in the category experimental::builtin.
In Perl 5.36.0, a new namespace, builtin, was created for new core functions that will not be present in every namespace, but will be available for importing. The namespace itself was considered experimental until Perl 5.39.2. Some specific functions within it remain experimental.
The ticket for this experiment is [perl #19764].
Introduced in Perl 5.36.0
Using this feature triggers warnings in the category experimental::defer.
This feature adds a new kind of block, a defer block, which will not be executed until the containing block is being exited.
The ticket for this experiment is [perl #17949].
Introduced in Perl 5.36.0
Using this feature triggers warnings in the category experimental::extra_paired_delimiters.
This feature allows for many non-ASCII pairs of mirroring delimiters, for example:
my @array = qw« tinker tailor soldier spy »;The ticket for this experiment is [perl #19765].
any and all list processing operatorsIntroduced in Perl 5.41.7.
Using these features triggers warnings in the categories experimental::any or experiment::all.
This adds new list processing operators named any and all, each as their own named feature.
The ticket for this experiment is [perl #22794].
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.
Introduced in Perl 5.005
Introduced in Perl 5.005
Introduced in Perl 5.6.0
See also perldebug, perldebtut
Introduced in Perl 5.6.0
Introduced in Perl 5.6.0
Introduced in Perl 5.6.1
See also perlfork
Introduced in Perl 5.6.0
Accepted in Perl 5.8.0
Introduced in Perl 5.6.0
Accepted in Perl 5.8.1
\N regex character classThe \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
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
Introduced in Perl 5.6.0
Accepted in Perl 5.20.0
See also perlsub
(*ACCEPT)
Introduced in Perl 5.10
Accepted in Perl 5.20.0
:pop IO pseudolayerSee also "PERLIO" in perlrun
Accepted in Perl 5.20.0
\s in regexp matches vertical tabAccepted in Perl 5.22.0
Introduced in Perl 5.20.0
Accepted in Perl 5.24.0
Introduced in Perl 5.18.0
Accepted in Perl 5.26.0
Introduced in Perl 5.22.0
Accepted in Perl 5.28.0
Introduced in Perl 5.28.0
Accepted in Perl 5.32.0
Introduced in Perl 5.28.0
Accepted in Perl 5.32.0
isa operatorIntroduced in Perl 5.32.0
Accepted in Perl 5.36.0
Introduced in Perl 5.20.0
Accepted in Perl 5.36.0
Introduced in Perl 5.18
Accepted in Perl 5.36
See : "Extended Bracketed Character Classes" in perlrecharclass
Introduced in Perl 5.34.0.
Accepted in Perl 5.40 when not using the optional finally block.
Introduced in Perl 5.22.0
Accepted in Perl 5.40
See also: "Constant Functions" in perlsub
Introduced in Perl 5.36.0.
Accepted in Perl 5.40.
This feature enables a parenthesized list of iteration variables for for rather than a single variable.
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).
Introduced in Perl 5.005
Removed in Perl 5.10
Introduced in Perl 5.005
Moved from Perl 5.9.0 to CPAN
Introduced in Perl 5.6.0
Removed in Perl 5.9.0
Getopt::Long upgraded to version 2.35
Removed in Perl 5.8.8
The -A command line switch
Introduced in Perl 5.9.0
Removed in Perl 5.9.5
Moved from Perl 5.10.1 to CPAN
legacyThe experimental legacy pragma was swallowed by the feature pragma.
Introduced in Perl 5.11.2
Removed in Perl 5.11.3
$_Using this feature triggered warnings in the category experimental::lexical_topic.
Introduced in Perl 5.10.0
Removed in Perl 5.24.0
Using this feature triggered warnings in the category experimental::autoderef.
Superseded by "Postfix dereference syntax".
Introduced in Perl 5.14.0
Removed in Perl 5.24.0
our can have an experimental optional attribute uniqueIntroduced in Perl 5.8.0
Deprecated in Perl 5.10.0
Removed in Perl 5.28.0
:win32 IO pseudolayerIntroduced in Perl 5.8.0 (or before)
Removed in Perl 5.36.0
~~)Introduced in Perl 5.10.0
Modified in Perl 5.10.1, 5.12.0
Deprecated in 5.38.0
Has been removed for 5.42.0
For a complete list of features check feature.
brian d foy <brian.d.foy@gmail.com>
Sébastien Aperghis-Tramoni <saper@cpan.org>
Copyright 2010, brian d foy <brian.d.foy@gmail.com>
You can use and redistribute this document under the same terms as Perl itself.