3 perlexperiment - A listing of experimental features in Perl
7 This document lists the current and past experimental features in the perl
8 core. Although all of these are documented with their appropriate topics,
9 this succinct listing gives you an overview and basic facts about their
12 So far we've merely tried to find and list the experimental features and infer
13 their inception, versions, etc. There's a lot of speculation here.
15 =head2 Current experiments
19 =item Smart match (C<~~>)
21 Introduced in Perl 5.10.0
23 Modified in Perl 5.10.1, 5.12.0
25 Using this feature triggers warnings in the category
26 C<experimental::smartmatch>.
28 The ticket for this feature is
29 L<[perl #119317]|https://rt.perl.org/rt3/Ticket/Display.html?id=119317>.
31 =item Pluggable keywords
33 The ticket for this feature is
34 L<[perl #119455]|https://rt.perl.org/rt3/Ticket/Display.html?id=119455>.
36 See L<perlapi/PL_keyword_plugin> for the mechanism.
38 Introduced in Perl 5.11.2
40 =item Regular Expression Set Operations
42 Introduced in Perl 5.18
44 The ticket for this feature is
45 L<[perl #119451]|https://rt.perl.org/rt3/Ticket/Display.html?id=119451>.
47 See also: L<perlrecharclass/Extended Bracketed Character Classes>
49 Using this feature triggers warnings in the category
50 C<experimental::regex_sets>.
52 =item Subroutine signatures
54 Introduced in Perl 5.20.0
56 Using this feature triggers warnings in the category
57 C<experimental::signatures>.
59 The ticket for this feature is
60 L<[perl #121481]|https://rt.perl.org/Ticket/Display.html?id=121481>.
62 =item Aliasing via reference
64 Introduced in Perl 5.22.0
66 Using this feature triggers warnings in the category
67 C<experimental::refaliasing>.
69 The ticket for this feature is
70 L<[perl #122947]|https://rt.perl.org/rt3/Ticket/Display.html?id=122947>.
72 See also: L<perlref/Assigning to References>
74 =item The "const" attribute
76 Introduced in Perl 5.22.0
78 Using this feature triggers warnings in the category
79 C<experimental::const_attr>.
81 The ticket for this feature is
82 L<[perl #123630]|https://rt.perl.org/rt3/Ticket/Display.html?id=123630>.
84 See also: L<perlsub/Constant Functions>
86 =item use re 'strict';
88 Introduced in Perl 5.22.0
90 Using this feature triggers warnings in the category
91 C<experimental::re_strict>.
93 See L<re/'strict' mode>
95 =item The <:win32> IO pseudolayer
97 The ticket for this feature is
98 L<[perl #119453]|https://rt.perl.org/rt3/Ticket/Display.html?id=119453>.
102 =item Declaring a reference to a variable
104 Introduced in Perl 5.26.0
106 Using this feature triggers warnings in the category
107 C<experimental::declared_refs>.
109 The ticket for this feature is
110 L<[perl #128654]|https://rt.perl.org/rt3/Ticket/Display.html?id=128654>.
112 See also: L<perlref/Declaring a Reference to a Variable>
114 =item There is an C<installhtml> target in the Makefile.
116 The ticket for this feature is
117 L<[perl #116487]|https://rt.perl.org/rt3/Ticket/Display.html?id=116487>.
119 =item Unicode in Perl on EBCDIC
123 Introduced in Perl 5.28.0
125 Using this feature triggers warnings in the category
126 C<experimental::script_run>.
128 See also: L<perlre/Script Runs>
133 =head2 Accepted features
135 These features were so wildly successful and played so well with others that
136 we decided to remove their experimental status and admit them as full, stable
137 features in the world of Perl, lavishing all the benefits and luxuries thereof.
138 They are also awarded +5 Stability and +3 Charisma.
144 Introduced in Perl 5.005
146 =item die accepts a reference
148 Introduced in Perl 5.005
152 Introduced in Perl 5.6.0
154 See also L<perldebug>, L<perldebtut>
156 =item Weak references
158 Introduced in Perl 5.6.0
160 =item Internal file glob
162 Introduced in Perl 5.6.0
164 =item fork() emulation
166 Introduced in Perl 5.6.1
170 =item -Dusemultiplicity -Duseithreads
172 Introduced in Perl 5.6.0
174 Accepted in Perl 5.8.0
176 =item Support for long doubles
178 Introduced in Perl 5.6.0
180 Accepted in Perl 5.8.1
182 =item The C<\N> regex character class
184 The C<\N> character class, not to be confused with the named character
185 sequence C<\N{NAME}>, denotes any non-newline character in a regular
188 Introduced in Perl 5.12
190 Exact version of acceptance unclear, but no later than Perl 5.18.
192 =item C<(?{code})> and C<(??{ code })>
194 Introduced in Perl 5.6.0
196 Accepted in Perl 5.20.0
200 =item Linux abstract Unix domain sockets
202 Introduced in Perl 5.9.2
204 Accepted before Perl 5.20.0. The Socket library is now primarily maintained
205 on CPAN, rather than in the perl core.
209 =item Lvalue subroutines
211 Introduced in Perl 5.6.0
213 Accepted in Perl 5.20.0
217 =item Backtracking control verbs
221 Introduced in Perl 5.10
223 Accepted in Perl 5.20.0
225 =item The <:pop> IO pseudolayer
229 Accepted in Perl 5.20.0
231 =item C<\s> in regexp matches vertical tab
233 Accepted in Perl 5.22.0
235 =item Postfix dereference syntax
237 Introduced in Perl 5.20.0
239 Accepted in Perl 5.24.0
241 =item Lexical subroutines
243 Introduced in Perl 5.18.0
245 Accepted in Perl 5.26.0
247 =item String- and number-specific bitwise operators
249 Introduced in Perl 5.22.0
251 Accepted in Perl 5.28.0
255 =head2 Removed features
257 These features are no longer considered experimental and their functionality
258 has disappeared. It's your own fault if you wrote production programs using
259 these features after we explicitly told you not to (see L<perlpolicy>).
263 =item 5.005-style threading
265 Introduced in Perl 5.005
271 Introduced in Perl 5.005
273 Moved from Perl 5.9.0 to CPAN
275 =item The pseudo-hash data type
277 Introduced in Perl 5.6.0
279 Removed in Perl 5.9.0
281 =item GetOpt::Long Options can now take multiple values at once (experimental)
283 C<Getopt::Long> upgraded to version 2.35
285 Removed in Perl 5.8.8
289 The C<-A> command line switch
291 Introduced in Perl 5.9.0
293 Removed in Perl 5.9.5
295 =item Test::Harness::Straps
297 Moved from Perl 5.10.1 to CPAN
301 The experimental C<legacy> pragma was swallowed by the C<feature> pragma.
303 Introduced in Perl 5.11.2
305 Removed in Perl 5.11.3
309 Using this feature triggered warnings in the category
310 C<experimental::lexical_topic>.
312 Introduced in Perl 5.10.0
314 Removed in Perl 5.24.0
316 =item Array and hash container functions accept references
318 Using this feature triggered warnings in the category
319 C<experimental::autoderef>.
321 Superseded by L</Postfix dereference syntax>.
323 Introduced in Perl 5.14.0
325 Removed in Perl 5.24.0
327 =item C<our> can have an experimental optional attribute C<unique>
329 Introduced in Perl 5.8.0
331 Deprecated in Perl 5.10.0
333 Removed in Perl 5.28.0
339 For a complete list of features check L<feature>.
343 brian d foy C<< <brian.d.foy@gmail.com> >>
345 SE<eacute>bastien Aperghis-Tramoni C<< <saper@cpan.org> >>
349 Copyright 2010, brian d foy C<< <brian.d.foy@gmail.com> >>
353 You can use and redistribute this document under the same terms as Perl