1PERLEXPERIMENT(1)      Perl Programmers Reference Guide      PERLEXPERIMENT(1)
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NAME

6       perlexperiment - A listing of experimental features in Perl
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DESCRIPTION

9       This document lists the current and past experimental features in the
10       perl core. Although all of these are documented with their appropriate
11       topics, this succinct listing gives you an overview and basic facts
12       about their status.
13
14       So far we've merely tried to find and list the experimental features
15       and infer their inception, versions, etc. There's a lot of speculation
16       here.
17
18   Current experiments
19       Smart match ("~~")
20               Introduced in Perl 5.10.0
21
22               Modified in Perl 5.10.1, 5.12.0
23
24               Using this feature triggers warnings in the category
25               "experimental::smartmatch".
26
27               The ticket for this experiment is [perl #13173]
28               <https://github.com/Perl/perl5/issues/13173>.
29
30       Pluggable keywords
31               Introduced in Perl 5.11.2
32
33               See "PL_keyword_plugin" in perlapi for the mechanism.
34
35               The ticket for this experiment is [perl #13199]
36               <https://github.com/Perl/perl5/issues/13199>.
37
38       Regular Expression Set Operations
39               Introduced in Perl 5.18
40
41               Using this feature triggers warnings in the category
42               "experimental::regex_sets".
43
44               The ticket for this experiment is [perl #13197]
45               <https://github.com/Perl/perl5/issues/13197>.
46
47               See also: "Extended Bracketed Character Classes" in
48               perlrecharclass
49
50       Subroutine signatures
51               Introduced in Perl 5.20.0
52
53               Using this feature triggers warnings in the category
54               "experimental::signatures".
55
56               The ticket for this experiment is [perl #13681]
57               <https://github.com/Perl/perl5/issues/13681>.
58
59       Aliasing via reference
60               Introduced in Perl 5.22.0
61
62               Using this feature triggers warnings in the category
63               "experimental::refaliasing".
64
65               The ticket for this experiment is [perl #14150]
66               <https://github.com/Perl/perl5/issues/14150>.
67
68               See also: "Assigning to References" in perlref
69
70       The "const" attribute
71               Introduced in Perl 5.22.0
72
73               Using this feature triggers warnings in the category
74               "experimental::const_attr".
75
76               The ticket for this experiment is [perl #14428]
77               <https://github.com/Perl/perl5/issues/14428>.
78
79               See also: "Constant Functions" in perlsub
80
81       use re 'strict';
82               Introduced in Perl 5.22.0
83
84               Using this feature triggers warnings in the category
85               "experimental::re_strict".
86
87               The ticket for this experiment is [perl #18755]
88               <https://github.com/Perl/perl5/issues/18755>
89
90               See "'strict' mode" in re
91
92       The <:win32> IO pseudolayer
93               Using this feature triggers warnings in the category
94               "experimental::win32_perlio".
95
96               The ticket for this experiment is [perl #13198]
97               <https://github.com/Perl/perl5/issues/13198>.
98
99               See also "PERLIO" in perlrun
100
101       Declaring a reference to a variable
102               Introduced in Perl 5.26.0
103
104               Using this feature triggers warnings in the category
105               "experimental::declared_refs".
106
107               The ticket for this experiment is [perl #15458]
108               <https://github.com/Perl/perl5/issues/15458>.
109
110               See also: "Declaring a Reference to a Variable" in perlref
111
112       There is an "installhtml" target in the Makefile.
113               The ticket for this experiment is [perl #12726]
114               <https://github.com/Perl/perl5/issues/12726>.
115
116       (Limited) Variable-length look-behind
117               Introduced in Perl 5.30.0.
118
119               Variability of up to 255 characters is handled.
120
121               Using this feature triggers warnings in the category
122               "experimental::vlb".
123
124               The ticket for this experiment is [perl #18756]
125               <https://github.com/Perl/perl5/issues/18756>.
126
127               See also: "(*positive_lookbehind:pattern)" in perlre and
128               "(*negative_lookbehind:pattern)" in perlre
129
130       Unicode private use character hooks
131               Introduced in Perl 5.30.0.
132
133               This feature is part of an interface intended for internal and
134               experimental use by the perl5 developers.  You are unlikely to
135               encounter it in the wild.
136
137               Using this feature triggers warnings in the category
138               "experimental::private_use".
139
140               The ticket for this experiment is [perl #18758]
141               <https://github.com/Perl/perl5/issues/18758>.
142
143       Unicode property wildcards
144               Introduced in Perl 5.30.0.
145
146               This feature allows regular expression matching against Unicode
147               character properties to be expressed more concisely.
148
149               Using this feature triggers warnings in the category
150               "experimental::uniprop_wildcards".
151
152               The ticket for this experiment is [perl #18759]
153               <https://github.com/Perl/perl5/issues/18759>.
154
155       isa infix operator
156               Introduced in Perl 5.32.0.
157
158               Using this feature triggers warnings in the category
159               "experimental::isa".
160
161               The ticket for this experiment is [perl #18754]
162               <https://github.com/Perl/perl5/issues/18754>
163
164       try/catch control structure
165               Introduced in Perl 5.34.0.
166
167               Using this feature triggers warnings in the category
168               "experimental::try".
169
170               The ticket for this experiment is [perl #18760]
171               <https://github.com/Perl/perl5/issues/18760>
172
173   Accepted features
174       These features were so wildly successful and played so well with others
175       that we decided to remove their experimental status and admit them as
176       full, stable features in the world of Perl, lavishing all the benefits
177       and luxuries thereof.  They are also awarded +5 Stability and +3
178       Charisma.
179
180       64-bit support
181               Introduced in Perl 5.005
182
183       die accepts a reference
184               Introduced in Perl 5.005
185
186       DB module
187               Introduced in Perl 5.6.0
188
189               See also perldebug, perldebtut
190
191       Weak references
192               Introduced in Perl 5.6.0
193
194       Internal file glob
195               Introduced in Perl 5.6.0
196
197       fork() emulation
198               Introduced in Perl 5.6.1
199
200               See also perlfork
201
202       -Dusemultiplicity -Duseithreads
203               Introduced in Perl 5.6.0
204
205               Accepted in Perl 5.8.0
206
207       Support for long doubles
208               Introduced in Perl 5.6.0
209
210               Accepted in Perl 5.8.1
211
212       The "\N" regex character class
213               The "\N" character class, not to be confused with the named
214               character sequence "\N{NAME}", denotes any non-newline
215               character in a regular expression.
216
217               Introduced in Perl 5.12
218
219               Exact version of acceptance unclear, but no later than Perl
220               5.18.
221
222       "(?{code})" and "(??{ code })"
223               Introduced in Perl 5.6.0
224
225               Accepted in Perl 5.20.0
226
227               See also perlre
228
229       Linux abstract Unix domain sockets
230               Introduced in Perl 5.9.2
231
232               Accepted before Perl 5.20.0.  The Socket library is now
233               primarily maintained on CPAN, rather than in the perl core.
234
235               See also Socket
236
237       Lvalue subroutines
238               Introduced in Perl 5.6.0
239
240               Accepted in Perl 5.20.0
241
242               See also perlsub
243
244       Backtracking control verbs
245               "(*ACCEPT)"
246
247               Introduced in Perl 5.10
248
249               Accepted in Perl 5.20.0
250
251       The <:pop> IO pseudolayer
252               See also "PERLIO" in perlrun
253
254               Accepted in Perl 5.20.0
255
256       "\s" in regexp matches vertical tab
257               Accepted in Perl 5.22.0
258
259       Postfix dereference syntax
260               Introduced in Perl 5.20.0
261
262               Accepted in Perl 5.24.0
263
264       Lexical subroutines
265               Introduced in Perl 5.18.0
266
267               Accepted in Perl 5.26.0
268
269       String- and number-specific bitwise operators
270               Introduced in Perl 5.22.0
271
272               Accepted in Perl 5.28.0
273
274       Alphabetic assertions
275               Introduced in Perl 5.28.0
276
277               Accepted in Perl 5.32.0
278
279       Script runs
280               Introduced in Perl 5.28.0
281
282               Accepted in Perl 5.32.0
283
284   Removed features
285       These features are no longer considered experimental and their
286       functionality has disappeared. It's your own fault if you wrote
287       production programs using these features after we explicitly told you
288       not to (see perlpolicy).
289
290       5.005-style threading
291               Introduced in Perl 5.005
292
293               Removed in Perl 5.10
294
295       perlcc  Introduced in Perl 5.005
296
297               Moved from Perl 5.9.0 to CPAN
298
299       The pseudo-hash data type
300               Introduced in Perl 5.6.0
301
302               Removed in Perl 5.9.0
303
304       GetOpt::Long Options can now take multiple values at once
305       (experimental)
306               "Getopt::Long" upgraded to version 2.35
307
308               Removed in Perl 5.8.8
309
310       Assertions
311               The "-A" command line switch
312
313               Introduced in Perl 5.9.0
314
315               Removed in Perl 5.9.5
316
317       Test::Harness::Straps
318               Moved from Perl 5.10.1 to CPAN
319
320       "legacy"
321               The experimental "legacy" pragma was swallowed by the "feature"
322               pragma.
323
324               Introduced in Perl 5.11.2
325
326               Removed in Perl 5.11.3
327
328       Lexical $_
329               Using this feature triggered warnings in the category
330               "experimental::lexical_topic".
331
332               Introduced in Perl 5.10.0
333
334               Removed in Perl 5.24.0
335
336       Array and hash container functions accept references
337               Using this feature triggered warnings in the category
338               "experimental::autoderef".
339
340               Superseded by "Postfix dereference syntax".
341
342               Introduced in Perl 5.14.0
343
344               Removed in Perl 5.24.0
345
346       "our" can have an experimental optional attribute "unique"
347               Introduced in Perl 5.8.0
348
349               Deprecated in Perl 5.10.0
350
351               Removed in Perl 5.28.0
352

SEE ALSO

354       For a complete list of features check feature.
355

AUTHORS

357       brian d foy "<brian.d.foy@gmail.com>"
358
359       Sebastien Aperghis-Tramoni "<saper@cpan.org>"
360

362       Copyright 2010, brian d foy "<brian.d.foy@gmail.com>"
363

LICENSE

365       You can use and redistribute this document under the same terms as Perl
366       itself.
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370perl v5.34.0                      2021-10-18                 PERLEXPERIMENT(1)
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