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 Postfix dereference syntax
96 Introduced in Perl 5.20.0
98 Using this feature triggers warnings in the category
99 C<experimental::postderef>.
101 The ticket for this feature is
102 L<[perl #120162]|https://rt.perl.org:443/rt3/Ticket/Display.html?id=120162>.
104 =item The <:win32> IO pseudolayer
106 The ticket for this feature is
107 L<[perl #119453]|https://rt.perl.org/rt3/Ticket/Display.html?id=119453>.
111 =item There is an C<installhtml> target in the Makefile.
113 The ticket for this feature is
114 L<[perl #116487]|https://rt.perl.org/rt3/Ticket/Display.html?id=116487>.
116 =item Unicode in Perl on EBCDIC
120 =head2 Accepted features
122 These features were so wildly successful and played so well with others that
123 we decided to remove their experimental status and admit them as full, stable
124 features in the world of Perl, lavishing all the benefits and luxuries thereof.
125 They are also awarded +5 Stability and +3 Charisma.
131 Introduced in Perl 5.005
133 =item die accepts a reference
135 Introduced in Perl 5.005
139 Introduced in Perl 5.6.0
141 See also L<perldebug>, L<perldebtut>
143 =item Weak references
145 Introduced in Perl 5.6.0
147 =item Internal file glob
149 Introduced in Perl 5.6.0
151 =item fork() emulation
153 Introduced in Perl 5.6.1
157 =item -Dusemultiplicity -Duseithreads
159 Introduced in Perl 5.6.0
161 Accepted in Perl 5.8.0
163 =item Support for long doubles
165 Introduced in Perl 5.6.0
167 Accepted in Perl 5.8.1
169 =item The C<\N> regex character class
171 The C<\N> character class, not to be confused with the named character
172 sequence C<\N{NAME}>, denotes any non-newline character in a regular
175 Introduced in Perl 5.12
177 Exact version of acceptance unclear, but no later than Perl 5.18.
179 =item C<(?{code})> and C<(??{ code })>
181 Introduced in Perl 5.6.0
183 Accepted in Perl 5.20.0
187 =item Linux abstract Unix domain sockets
189 Introduced in Perl 5.9.2
191 Accepted before Perl 5.20.0. The Socket library is now primarily maintained
192 on CPAN, rather than in the perl core.
196 =item Lvalue subroutines
198 Introduced in Perl 5.6.0
200 Accepted in Perl 5.20.0
204 =item Backtracking control verbs
208 Introduced in: Perl 5.10
210 Accepted in Perl 5.20.0
212 =item The <:pop> IO pseudolayer
216 Accepted in Perl 5.20.0
220 =head2 Removed features
222 These features are no longer considered experimental and their functionality
223 has disappeared. It's your own fault if you wrote production programs using
224 these features after we explicitly told you not to (see L<perlpolicy>).
228 =item 5.005-style threading
230 Introduced in Perl 5.005
236 Introduced in Perl 5.005
238 Moved from Perl 5.9.0 to CPAN
240 =item The pseudo-hash data type
242 Introduced in Perl 5.6.0
244 Removed in Perl 5.9.0
246 =item GetOpt::Long Options can now take multiple values at once (experimental)
248 C<Getopt::Long> upgraded to version 2.35
250 Removed in Perl 5.8.8
254 The C<-A> command line switch
256 Introduced in Perl 5.9.0
258 Removed in Perl 5.9.5
260 =item Test::Harness::Straps
262 Moved from Perl 5.10.1 to CPAN
266 The experimental C<legacy> pragma was swallowed by the C<feature> pragma.
268 Introduced in: 5.11.2
276 brian d foy C<< <brian.d.foy@gmail.com> >>
278 SE<eacute>bastien Aperghis-Tramoni C<< <saper@cpan.org> >>
282 Copyright 2010, brian d foy C<< <brian.d.foy@gmail.com> >>
286 You can use and redistribute this document under the same terms as Perl