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.
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Introduced in Perl 5.10.0
Modified in Perl 5.10.1, 5.12.0
Deprecated in 5.38.0
Will be removed in 5.42.0
Using this feature triggers warnings in the category deprecated.
deprecated
The ticket for this experiment is [perl #13173].
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.
experimental::refaliasing
The ticket for this experiment is [perl #14150].
See also: "Assigning to References" in perlref
Using this feature triggers warnings in the category experimental::const_attr.
experimental::const_attr
The ticket for this experiment is [perl #14428].
See also: "Constant Functions" in perlsub
Using this feature triggers warnings in the category experimental::re_strict.
experimental::re_strict
The ticket for this experiment is [perl #18755]
See "'strict' mode" in re
Introduced in Perl 5.26.0
Using this feature triggers warnings in the category experimental::declared_refs.
experimental::declared_refs
The ticket for this experiment is [perl #15458].
See also: "Declaring a Reference to a Variable" in perlref
installhtml
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.
experimental::vlb
The ticket for this experiment is [perl #18756].
See also: "(*positive_lookbehind:pattern)" in perlre and "(*negative_lookbehind:pattern)" in perlre
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.
experimental::private_use
The ticket for this experiment is [perl #18758].
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.
experimental::uniprop_wildcards
The ticket for this experiment is [perl #18759].
Introduced in Perl 5.34.0.
Using this feature triggers warnings in the category experimental::try.
experimental::try
The ticket for this experiment is [perl #18760]
@_
Introduced 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.
experimental::args_array_with_signatures
$_[$index]
shift
pop
Introduced in Perl 5.36.0.
Using this feature triggers warnings in the category experimental::for_list.
experimental::for_list
This feature enables a parenthesized list of iteration variables for for rather than a single variable.
for
The ticket for this experiment is [perl #18744].
Using this feature triggers warnings in the category experimental::builtin.
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 is considered an experiment. Specific functions within it may also be experimental.
builtin
The ticket for this experiment is [perl #19764].
Introduced in Perl 5.36.0
Using this feature triggers warnings in the category experimental::defer.
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.
defer
The ticket for this experiment is [perl #17949].
Using this feature triggers warnings in the category experimental::extra_paired_delimiters.
experimental::extra_paired_delimiters
This feature allows for many non-ASCII pairs of mirroring delimiters, for example:
my @array = qw« tinker tailer soldier spy »;
The ticket for this experiment is [perl #19765].
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 5.6.0
See also perldebug, perldebtut
Introduced in Perl 5.6.1
See also perlfork
Accepted in Perl 5.8.0
Accepted in Perl 5.8.1
\N
The \N character class, not to be confused with the named character sequence \N{NAME}, denotes any non-newline character in a regular expression.
\N{NAME}
Introduced in Perl 5.12
Exact version of acceptance unclear, but no later than Perl 5.18.
(?{code})
(??{ code })
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
See also perlsub
(*ACCEPT)
Introduced in Perl 5.10
:pop
See also "PERLIO" in perlrun
\s
Accepted 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
Accepted in Perl 5.28.0
Introduced in Perl 5.28.0
Accepted in Perl 5.32.0
isa
Introduced in Perl 5.32.0
Accepted in Perl 5.36.0
Introduced in Perl 5.18
Accepted in Perl 5.36
See : "Extended Bracketed Character Classes" in perlrecharclass
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).
Removed in Perl 5.10
Moved from Perl 5.9.0 to CPAN
Removed in Perl 5.9.0
Getopt::Long upgraded to version 2.35
Getopt::Long
Removed in Perl 5.8.8
The -A command line switch
-A
Introduced in Perl 5.9.0
Removed in Perl 5.9.5
Moved from Perl 5.10.1 to CPAN
legacy
The experimental legacy pragma was swallowed by the feature pragma.
feature
Removed in Perl 5.11.3
$_
Using this feature triggered warnings in the category experimental::lexical_topic.
experimental::lexical_topic
Removed in Perl 5.24.0
Using this feature triggered warnings in the category experimental::autoderef.
experimental::autoderef
Superseded by "Postfix dereference syntax".
Introduced in Perl 5.14.0
our
unique
Introduced in Perl 5.8.0
Deprecated in Perl 5.10.0
Removed in Perl 5.28.0
:win32
Introduced in Perl 5.8.0 (or before)
Removed in Perl 5.36.0
For a complete list of features check feature.
brian d foy <brian.d.foy@gmail.com>
<brian.d.foy@gmail.com>
Sébastien Aperghis-Tramoni <saper@cpan.org>
<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.
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cpanm
cpanm less
CPAN shell
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