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>.
42 Introduced in Perl 5.10.0
44 Using this feature triggers warnings in the category
45 C<experimental::lexical_topic>.
47 The ticket for this feature is
48 L<[perl #119315]|https://rt.perl.org/rt3/Ticket/Display.html?id=119315>.
50 =item Pluggable keywords
52 The ticket for this feature is
53 L<[perl #119455]|https://rt.perl.org/rt3/Ticket/Display.html?id=119455>.
55 See L<perlapi/PL_keyword_plugin> for the mechanism.
57 Introduced in: Perl 5.11.2
59 =item Array and hash container functions accept references
61 Introduced in Perl 5.14.0
63 The ticket for this feature is
64 L<[perl #119437]|https://rt.perl.org/rt3/Ticket/Display.html?id=119437>.
66 =item Lexical subroutines
68 Introduced in: Perl 5.18
70 See also: L<perlsub/Lexical Subroutines>
72 Using this feature triggers warnings in the category
73 C<experimental::lexical_subs>.
75 The ticket for this feature is
76 L<[perl #120085]|https://rt.perl.org/rt3/Ticket/Display.html?id=120085>.
78 =item Regular Expression Set Operations
80 Introduced in: Perl 5.18
82 The ticket for this feature is
83 L<[perl #119451]|https://rt.perl.org/rt3/Ticket/Display.html?id=119451>.
85 See also: L<perlrecharclass/Extended Bracketed Character Classes>
87 Using this feature triggers warnings in the category
88 C<experimental::regex_sets>.
90 =item C<\s> in regexp matches vertical tab
92 Introduced in Perl 5.18
94 =item Subroutine signatures
96 Introduced in Perl 5.20.0
98 Using this feature triggers warnings in the category
99 C<experimental::signatures>.
101 The ticket for this feature is
102 L<[perl #121481]|https://rt.perl.org/Ticket/Display.html?id=121481>.
104 =item Postfix dereference syntax
106 Introduced in Perl 5.20.0
108 Using this feature triggers warnings in the category
109 C<experimental::postderef>.
111 The ticket for this feature is
112 L<[perl #120162]|https://rt.perl.org:443/rt3/Ticket/Display.html?id=120162>.
114 =item Aliasing via reference
116 Introduced in Perl 5.22.0
118 Using this feature triggers warnings in the category
119 C<experimental::refaliasing>.
121 The ticket for this feature is
122 L<[perl #122947]|https://rt.perl.org/rt3/Ticket/Display.html?id=122947>.
124 See also: L<perlref/Assigning to References>
126 =item The "const" attribute
128 Introduced in Perl 5.22.0
130 Using this feature triggers warnings in the category
131 C<experimental::const_attr>.
133 The ticket for this feature is
134 L<[perl #123630]|https://rt.perl.org/rt3/Ticket/Display.html?id=123630>.
136 See also: L<perlsub/Constant Functions>
138 =item The <:win32> IO pseudolayer
140 The ticket for this feature is
141 L<[perl #119453]|https://rt.perl.org/rt3/Ticket/Display.html?id=119453>.
145 =item There is an C<installhtml> target in the Makefile.
147 The ticket for this feature is
148 L<[perl #116487]|https://rt.perl.org/rt3/Ticket/Display.html?id=116487>.
150 =item Unicode in Perl on EBCDIC
154 =head2 Accepted features
156 These features were so wildly successful and played so well with others that
157 we decided to remove their experimental status and admit them as full, stable
158 features in the world of Perl, lavishing all the benefits and luxuries thereof.
159 They are also awarded +5 Stability and +3 Charisma.
165 Introduced in Perl 5.005
167 =item die accepts a reference
169 Introduced in Perl 5.005
173 Introduced in Perl 5.6.0
175 See also L<perldebug>, L<perldebtut>
177 =item Weak references
179 Introduced in Perl 5.6.0
181 =item Internal file glob
183 Introduced in Perl 5.6.0
185 =item fork() emulation
187 Introduced in Perl 5.6.1
191 =item -Dusemultiplicity -Duseithreads
193 Introduced in Perl 5.6.0
195 Accepted in Perl 5.8.0
197 =item Support for long doubles
199 Introduced in Perl 5.6.0
201 Accepted in Perl 5.8.1
203 =item The C<\N> regex character class
205 The C<\N> character class, not to be confused with the named character
206 sequence C<\N{NAME}>, denotes any non-newline character in a regular
209 Introduced in Perl 5.12
211 Exact version of acceptance unclear, but no later than Perl 5.18.
213 =item C<(?{code})> and C<(??{ code })>
215 Introduced in Perl 5.6.0
217 Accepted in Perl 5.20.0
221 =item Linux abstract Unix domain sockets
223 Introduced in Perl 5.9.2
225 Accepted before Perl 5.20.0. The Socket library is now primarily maintained
226 on CPAN, rather than in the perl core.
230 =item Lvalue subroutines
232 Introduced in Perl 5.6.0
234 Accepted in Perl 5.20.0
238 =item Backtracking control verbs
242 Introduced in: Perl 5.10
244 Accepted in Perl 5.20.0
246 =item The <:pop> IO pseudolayer
250 Accepted in Perl 5.20.0
254 =head2 Removed features
256 These features are no longer considered experimental and their functionality
257 has disappeared. It's your own fault if you wrote production programs using
258 these features after we explicitly told you not to (see L<perlpolicy>).
262 =item 5.005-style threading
264 Introduced in Perl 5.005
270 Introduced in Perl 5.005
272 Moved from Perl 5.9.0 to CPAN
274 =item The pseudo-hash data type
276 Introduced in Perl 5.6.0
278 Removed in Perl 5.9.0
280 =item GetOpt::Long Options can now take multiple values at once (experimental)
282 C<Getopt::Long> upgraded to version 2.35
284 Removed in Perl 5.8.8
288 The C<-A> command line switch
290 Introduced in Perl 5.9.0
292 Removed in Perl 5.9.5
294 =item Test::Harness::Straps
296 Moved from Perl 5.10.1 to CPAN
300 The experimental C<legacy> pragma was swallowed by the C<feature> pragma.
302 Introduced in: 5.11.2
310 For a complete list of features check L<feature>.
314 brian d foy C<< <brian.d.foy@gmail.com> >>
316 SE<eacute>bastien Aperghis-Tramoni C<< <saper@cpan.org> >>
320 Copyright 2010, brian d foy C<< <brian.d.foy@gmail.com> >>
324 You can use and redistribute this document under the same terms as Perl