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 C<our> can now have an experimental optional attribute C<unique>
21 Introduced in Perl 5.8.0
23 Deprecated in Perl 5.10.0
25 The ticket for this feature is
26 L<[perl #119313]|https://rt.perl.org/rt3/Ticket/Display.html?id=119313>.
28 =item Smart match (C<~~>)
30 Introduced in Perl 5.10.0
32 Modified in Perl 5.10.1, 5.12.0
34 Using this feature triggers warnings in the category
35 C<experimental::smartmatch>.
37 The ticket for this feature is
38 L<[perl #119317]|https://rt.perl.org/rt3/Ticket/Display.html?id=119317>.
40 =item Pluggable keywords
42 The ticket for this feature is
43 L<[perl #119455]|https://rt.perl.org/rt3/Ticket/Display.html?id=119455>.
45 See L<perlapi/PL_keyword_plugin> for the mechanism.
47 Introduced in Perl 5.11.2
49 =item Regular Expression Set Operations
51 Introduced in Perl 5.18
53 The ticket for this feature is
54 L<[perl #119451]|https://rt.perl.org/rt3/Ticket/Display.html?id=119451>.
56 See also: L<perlrecharclass/Extended Bracketed Character Classes>
58 Using this feature triggers warnings in the category
59 C<experimental::regex_sets>.
61 =item Subroutine signatures
63 Introduced in Perl 5.20.0
65 Using this feature triggers warnings in the category
66 C<experimental::signatures>.
68 The ticket for this feature is
69 L<[perl #121481]|https://rt.perl.org/Ticket/Display.html?id=121481>.
71 =item Aliasing via reference
73 Introduced in Perl 5.22.0
75 Using this feature triggers warnings in the category
76 C<experimental::refaliasing>.
78 The ticket for this feature is
79 L<[perl #122947]|https://rt.perl.org/rt3/Ticket/Display.html?id=122947>.
81 See also: L<perlref/Assigning to References>
83 =item The "const" attribute
85 Introduced in Perl 5.22.0
87 Using this feature triggers warnings in the category
88 C<experimental::const_attr>.
90 The ticket for this feature is
91 L<[perl #123630]|https://rt.perl.org/rt3/Ticket/Display.html?id=123630>.
93 See also: L<perlsub/Constant Functions>
95 =item use re 'strict';
97 Introduced in Perl 5.22.0
99 Using this feature triggers warnings in the category
100 C<experimental::re_strict>.
102 See L<re/'strict' mode>
104 =item String- and number-specific bitwise operators
106 Introduced in Perl 5.22.0
108 See also: L<perlop/Bitwise String Operators>
110 Using this feature triggers warnings in the category
111 C<experimental::bitwise>.
113 The ticket for this feature is
114 L<[perl #123707]|https://rt.perl.org/rt3/Ticket/Display.html?id=123707>.
116 =item The <:win32> IO pseudolayer
118 The ticket for this feature is
119 L<[perl #119453]|https://rt.perl.org/rt3/Ticket/Display.html?id=119453>.
123 =item Declaring a reference to a variable
125 Introduced in Perl 5.26.0
127 Using this feature triggers warnings in the category
128 C<experimental::declared_refs>.
130 The ticket for this feature is
131 L<[perl #128654]|https://rt.perl.org/rt3/Ticket/Display.html?id=128654>.
133 See also: L<perlref/Declaring a Reference to a Variable>
135 =item There is an C<installhtml> target in the Makefile.
137 The ticket for this feature is
138 L<[perl #116487]|https://rt.perl.org/rt3/Ticket/Display.html?id=116487>.
140 =item Unicode in Perl on EBCDIC
144 =head2 Accepted features
146 These features were so wildly successful and played so well with others that
147 we decided to remove their experimental status and admit them as full, stable
148 features in the world of Perl, lavishing all the benefits and luxuries thereof.
149 They are also awarded +5 Stability and +3 Charisma.
155 Introduced in Perl 5.005
157 =item die accepts a reference
159 Introduced in Perl 5.005
163 Introduced in Perl 5.6.0
165 See also L<perldebug>, L<perldebtut>
167 =item Weak references
169 Introduced in Perl 5.6.0
171 =item Internal file glob
173 Introduced in Perl 5.6.0
175 =item fork() emulation
177 Introduced in Perl 5.6.1
181 =item -Dusemultiplicity -Duseithreads
183 Introduced in Perl 5.6.0
185 Accepted in Perl 5.8.0
187 =item Support for long doubles
189 Introduced in Perl 5.6.0
191 Accepted in Perl 5.8.1
193 =item The C<\N> regex character class
195 The C<\N> character class, not to be confused with the named character
196 sequence C<\N{NAME}>, denotes any non-newline character in a regular
199 Introduced in Perl 5.12
201 Exact version of acceptance unclear, but no later than Perl 5.18.
203 =item C<(?{code})> and C<(??{ code })>
205 Introduced in Perl 5.6.0
207 Accepted in Perl 5.20.0
211 =item Linux abstract Unix domain sockets
213 Introduced in Perl 5.9.2
215 Accepted before Perl 5.20.0. The Socket library is now primarily maintained
216 on CPAN, rather than in the perl core.
220 =item Lvalue subroutines
222 Introduced in Perl 5.6.0
224 Accepted in Perl 5.20.0
228 =item Backtracking control verbs
232 Introduced in Perl 5.10
234 Accepted in Perl 5.20.0
236 =item The <:pop> IO pseudolayer
240 Accepted in Perl 5.20.0
242 =item C<\s> in regexp matches vertical tab
244 Accepted in Perl 5.22.0
246 =item Postfix dereference syntax
248 Introduced in Perl 5.20.0
250 Accepted in Perl 5.24.0
252 =item Lexical subroutines
254 Introduced in Perl 5.18.0
256 Accepted in Perl 5.26.0
260 =head2 Removed features
262 These features are no longer considered experimental and their functionality
263 has disappeared. It's your own fault if you wrote production programs using
264 these features after we explicitly told you not to (see L<perlpolicy>).
268 =item 5.005-style threading
270 Introduced in Perl 5.005
276 Introduced in Perl 5.005
278 Moved from Perl 5.9.0 to CPAN
280 =item The pseudo-hash data type
282 Introduced in Perl 5.6.0
284 Removed in Perl 5.9.0
286 =item GetOpt::Long Options can now take multiple values at once (experimental)
288 C<Getopt::Long> upgraded to version 2.35
290 Removed in Perl 5.8.8
294 The C<-A> command line switch
296 Introduced in Perl 5.9.0
298 Removed in Perl 5.9.5
300 =item Test::Harness::Straps
302 Moved from Perl 5.10.1 to CPAN
306 The experimental C<legacy> pragma was swallowed by the C<feature> pragma.
308 Introduced in Perl 5.11.2
310 Removed in Perl 5.11.3
314 Using this feature triggered warnings in the category
315 C<experimental::lexical_topic>.
317 Introduced in Perl 5.10.0
319 Removed in Perl 5.24.0
321 =item Array and hash container functions accept references
323 Using this feature triggered warnings in the category
324 C<experimental::autoderef>.
326 Superseded by L</Postfix dereference syntax>.
328 Introduced in Perl 5.14.0
330 Removed in Perl 5.24.0
336 For a complete list of features check L<feature>.
340 brian d foy C<< <brian.d.foy@gmail.com> >>
342 SE<eacute>bastien Aperghis-Tramoni C<< <saper@cpan.org> >>
346 Copyright 2010, brian d foy C<< <brian.d.foy@gmail.com> >>
350 You can use and redistribute this document under the same terms as Perl