NAME
perlexperiment - A listing of experimental features in Perl
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
- 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 experiment is [perl #13173].
- Pluggable keywords
-
Introduced in Perl 5.11.2
See "PL_keyword_plugin" in perlapi for the mechanism.
The ticket for this experiment is [perl #13199].
- Aliasing via reference
-
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
- The "const" attribute
-
Introduced in Perl 5.22.0
Using this feature triggers warnings in the category
experimental::const_attr.The ticket for this experiment is [perl #14428].
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.The ticket for this experiment is [perl #18755]
- Declaring a reference to a variable
-
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].
- There is an
installhtmltarget in the Makefile. -
The ticket for this experiment is [perl #12726].
- (Limited) Variable-length look-behind
-
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
- Unicode private use character hooks
-
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].
- Unicode property wildcards
-
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].
- try/catch control structure
-
Introduced in Perl 5.34.0.
Using this feature triggers warnings in the category
experimental::try.The ticket for this experiment is [perl #18760]
- Use of
@_within subroutine signatures -
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 categoryexperimental::args_array_with_signatures. This includes@_directly, elements of it such as$_[$index], or situations where the default arguments array is accessed implicitly such asshiftorpopwithout arguments.
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
\Nregex character class -
The
\Ncharacter 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
:popIO pseudolayer -
See also "PERLIO" in perlrun
Accepted in Perl 5.20.0
\sin regexp matches vertical tab-
Accepted in Perl 5.22.0
- Postfix dereference syntax
-
Introduced in Perl 5.20.0
Accepted in Perl 5.24.0
- Lexical subroutines
-
Introduced in Perl 5.18.0
Accepted in Perl 5.26.0
- String- and number-specific bitwise operators
-
Introduced in Perl 5.22.0
Accepted in Perl 5.28.0
- Alphabetic assertions
-
Introduced in Perl 5.28.0
Accepted in Perl 5.32.0
- Script runs
-
Introduced in Perl 5.28.0
Accepted in Perl 5.32.0
- The infix
isaoperator -
Introduced in Perl 5.32.0
Accepted in Perl 5.36.0
- Subroutine signatures
-
Introduced in Perl 5.20.0
Accepted in Perl 5.36.0
- Regular Expression Set Operations
-
Introduced in Perl 5.18
Accepted in Perl 5.36
See : "Extended Bracketed Character Classes" in perlrecharclass
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::Longupgraded to version 2.35Removed in Perl 5.8.8
- Assertions
-
The
-Acommand line switchIntroduced 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
legacypragma was swallowed by thefeaturepragma.Introduced in Perl 5.11.2
Removed in Perl 5.11.3
- Lexical
$_ -
Using this feature triggered warnings in the category
experimental::lexical_topic.Introduced in Perl 5.10.0
Removed in Perl 5.24.0
- Array and hash container functions accept references
-
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
ourcan have an experimental optional attributeunique-
Introduced in Perl 5.8.0
Deprecated in Perl 5.10.0
Removed in Perl 5.28.0
- The
:win32IO pseudolayer -
Introduced in Perl 5.8.0 (or before)
Removed in Perl 5.36.0
SEE ALSO
For a complete list of features check feature.
AUTHORS
brian d foy <brian.d.foy@gmail.com>
Sébastien Aperghis-Tramoni <saper@cpan.org>
COPYRIGHT
Copyright 2010, brian d foy <brian.d.foy@gmail.com>
LICENSE
You can use and redistribute this document under the same terms as Perl itself.