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>
130 =item Alphabetic assertions
132 Introduced in Perl 5.28.0
134 Using this feature triggers warnings in the category
135 C<experimental::alpha_assertions>.
137 See also: L<perlre/Extended Patterns>.
141 =head2 Accepted features
143 These features were so wildly successful and played so well with others that
144 we decided to remove their experimental status and admit them as full, stable
145 features in the world of Perl, lavishing all the benefits and luxuries thereof.
146 They are also awarded +5 Stability and +3 Charisma.
152 Introduced in Perl 5.005
154 =item die accepts a reference
156 Introduced in Perl 5.005
160 Introduced in Perl 5.6.0
162 See also L<perldebug>, L<perldebtut>
164 =item Weak references
166 Introduced in Perl 5.6.0
168 =item Internal file glob
170 Introduced in Perl 5.6.0
172 =item fork() emulation
174 Introduced in Perl 5.6.1
178 =item -Dusemultiplicity -Duseithreads
180 Introduced in Perl 5.6.0
182 Accepted in Perl 5.8.0
184 =item Support for long doubles
186 Introduced in Perl 5.6.0
188 Accepted in Perl 5.8.1
190 =item The C<\N> regex character class
192 The C<\N> character class, not to be confused with the named character
193 sequence C<\N{NAME}>, denotes any non-newline character in a regular
196 Introduced in Perl 5.12
198 Exact version of acceptance unclear, but no later than Perl 5.18.
200 =item C<(?{code})> and C<(??{ code })>
202 Introduced in Perl 5.6.0
204 Accepted in Perl 5.20.0
208 =item Linux abstract Unix domain sockets
210 Introduced in Perl 5.9.2
212 Accepted before Perl 5.20.0. The Socket library is now primarily maintained
213 on CPAN, rather than in the perl core.
217 =item Lvalue subroutines
219 Introduced in Perl 5.6.0
221 Accepted in Perl 5.20.0
225 =item Backtracking control verbs
229 Introduced in Perl 5.10
231 Accepted in Perl 5.20.0
233 =item The <:pop> IO pseudolayer
237 Accepted in Perl 5.20.0
239 =item C<\s> in regexp matches vertical tab
241 Accepted in Perl 5.22.0
243 =item Postfix dereference syntax
245 Introduced in Perl 5.20.0
247 Accepted in Perl 5.24.0
249 =item Lexical subroutines
251 Introduced in Perl 5.18.0
253 Accepted in Perl 5.26.0
255 =item String- and number-specific bitwise operators
257 Introduced in Perl 5.22.0
259 Accepted in Perl 5.28.0
263 =head2 Removed features
265 These features are no longer considered experimental and their functionality
266 has disappeared. It's your own fault if you wrote production programs using
267 these features after we explicitly told you not to (see L<perlpolicy>).
271 =item 5.005-style threading
273 Introduced in Perl 5.005
279 Introduced in Perl 5.005
281 Moved from Perl 5.9.0 to CPAN
283 =item The pseudo-hash data type
285 Introduced in Perl 5.6.0
287 Removed in Perl 5.9.0
289 =item GetOpt::Long Options can now take multiple values at once (experimental)
291 C<Getopt::Long> upgraded to version 2.35
293 Removed in Perl 5.8.8
297 The C<-A> command line switch
299 Introduced in Perl 5.9.0
301 Removed in Perl 5.9.5
303 =item Test::Harness::Straps
305 Moved from Perl 5.10.1 to CPAN
309 The experimental C<legacy> pragma was swallowed by the C<feature> pragma.
311 Introduced in Perl 5.11.2
313 Removed in Perl 5.11.3
317 Using this feature triggered warnings in the category
318 C<experimental::lexical_topic>.
320 Introduced in Perl 5.10.0
322 Removed in Perl 5.24.0
324 =item Array and hash container functions accept references
326 Using this feature triggered warnings in the category
327 C<experimental::autoderef>.
329 Superseded by L</Postfix dereference syntax>.
331 Introduced in Perl 5.14.0
333 Removed in Perl 5.24.0
335 =item C<our> can have an experimental optional attribute C<unique>
337 Introduced in Perl 5.8.0
339 Deprecated in Perl 5.10.0
341 Removed in Perl 5.28.0
347 For a complete list of features check L<feature>.
351 brian d foy C<< <brian.d.foy@gmail.com> >>
353 SE<eacute>bastien Aperghis-Tramoni C<< <saper@cpan.org> >>
357 Copyright 2010, brian d foy C<< <brian.d.foy@gmail.com> >>
361 You can use and redistribute this document under the same terms as Perl