| Filename | /home/leont/perl5/perlbrew/perls/perl-5.32.0/lib/5.32.0/feature.pm |
| Statements | Executed 68 statements in 47µs |
| Calls | P | F | Exclusive Time |
Inclusive Time |
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|---|---|---|---|---|---|
| 1 | 1 | 1 | 22µs | 22µs | feature::__common |
| 1 | 1 | 1 | 2µs | 24µs | feature::import |
| 0 | 0 | 0 | 0s | 0s | feature::croak |
| 0 | 0 | 0 | 0s | 0s | feature::unimport |
| 0 | 0 | 0 | 0s | 0s | feature::unknown_feature |
| 0 | 0 | 0 | 0s | 0s | feature::unknown_feature_bundle |
| Line | State ments |
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|---|---|---|---|---|---|
| 1 | # -*- buffer-read-only: t -*- | ||||
| 2 | # !!!!!!! DO NOT EDIT THIS FILE !!!!!!! | ||||
| 3 | # This file is built by regen/feature.pl. | ||||
| 4 | # Any changes made here will be lost! | ||||
| 5 | |||||
| 6 | package feature; | ||||
| 7 | |||||
| 8 | 1 | 300ns | our $VERSION = '1.58'; | ||
| 9 | |||||
| 10 | 1 | 3µs | our %feature = ( | ||
| 11 | fc => 'feature_fc', | ||||
| 12 | isa => 'feature_isa', | ||||
| 13 | say => 'feature_say', | ||||
| 14 | state => 'feature_state', | ||||
| 15 | switch => 'feature_switch', | ||||
| 16 | bitwise => 'feature_bitwise', | ||||
| 17 | indirect => 'feature_indirect', | ||||
| 18 | evalbytes => 'feature_evalbytes', | ||||
| 19 | signatures => 'feature_signatures', | ||||
| 20 | current_sub => 'feature___SUB__', | ||||
| 21 | refaliasing => 'feature_refaliasing', | ||||
| 22 | postderef_qq => 'feature_postderef_qq', | ||||
| 23 | unicode_eval => 'feature_unieval', | ||||
| 24 | declared_refs => 'feature_myref', | ||||
| 25 | unicode_strings => 'feature_unicode', | ||||
| 26 | ); | ||||
| 27 | |||||
| 28 | 1 | 4µs | our %feature_bundle = ( | ||
| 29 | "5.10" => [qw(indirect say state switch)], | ||||
| 30 | "5.11" => [qw(indirect say state switch unicode_strings)], | ||||
| 31 | "5.15" => [qw(current_sub evalbytes fc indirect say state switch unicode_eval unicode_strings)], | ||||
| 32 | "5.23" => [qw(current_sub evalbytes fc indirect postderef_qq say state switch unicode_eval unicode_strings)], | ||||
| 33 | "5.27" => [qw(bitwise current_sub evalbytes fc indirect postderef_qq say state switch unicode_eval unicode_strings)], | ||||
| 34 | "all" => [qw(bitwise current_sub declared_refs evalbytes fc indirect isa postderef_qq refaliasing say signatures state switch unicode_eval unicode_strings)], | ||||
| 35 | "default" => [qw(indirect)], | ||||
| 36 | ); | ||||
| 37 | |||||
| 38 | 1 | 500ns | $feature_bundle{"5.12"} = $feature_bundle{"5.11"}; | ||
| 39 | 1 | 100ns | $feature_bundle{"5.13"} = $feature_bundle{"5.11"}; | ||
| 40 | 1 | 100ns | $feature_bundle{"5.14"} = $feature_bundle{"5.11"}; | ||
| 41 | 1 | 400ns | $feature_bundle{"5.16"} = $feature_bundle{"5.15"}; | ||
| 42 | 1 | 200ns | $feature_bundle{"5.17"} = $feature_bundle{"5.15"}; | ||
| 43 | 1 | 100ns | $feature_bundle{"5.18"} = $feature_bundle{"5.15"}; | ||
| 44 | 1 | 100ns | $feature_bundle{"5.19"} = $feature_bundle{"5.15"}; | ||
| 45 | 1 | 100ns | $feature_bundle{"5.20"} = $feature_bundle{"5.15"}; | ||
| 46 | 1 | 100ns | $feature_bundle{"5.21"} = $feature_bundle{"5.15"}; | ||
| 47 | 1 | 100ns | $feature_bundle{"5.22"} = $feature_bundle{"5.15"}; | ||
| 48 | 1 | 100ns | $feature_bundle{"5.24"} = $feature_bundle{"5.23"}; | ||
| 49 | 1 | 100ns | $feature_bundle{"5.25"} = $feature_bundle{"5.23"}; | ||
| 50 | 1 | 100ns | $feature_bundle{"5.26"} = $feature_bundle{"5.23"}; | ||
| 51 | 1 | 100ns | $feature_bundle{"5.28"} = $feature_bundle{"5.27"}; | ||
| 52 | 1 | 100ns | $feature_bundle{"5.29"} = $feature_bundle{"5.27"}; | ||
| 53 | 1 | 100ns | $feature_bundle{"5.30"} = $feature_bundle{"5.27"}; | ||
| 54 | 1 | 100ns | $feature_bundle{"5.31"} = $feature_bundle{"5.27"}; | ||
| 55 | 1 | 100ns | $feature_bundle{"5.32"} = $feature_bundle{"5.27"}; | ||
| 56 | 1 | 600ns | $feature_bundle{"5.9.5"} = $feature_bundle{"5.10"}; | ||
| 57 | 1 | 700ns | my %noops = ( | ||
| 58 | postderef => 1, | ||||
| 59 | lexical_subs => 1, | ||||
| 60 | ); | ||||
| 61 | 1 | 200ns | my %removed = ( | ||
| 62 | array_base => 1, | ||||
| 63 | ); | ||||
| 64 | |||||
| 65 | 1 | 100ns | our $hint_shift = 26; | ||
| 66 | 1 | 0s | our $hint_mask = 0x1c000000; | ||
| 67 | 1 | 500ns | our @hint_bundles = qw( default 5.10 5.11 5.15 5.23 5.27 ); | ||
| 68 | |||||
| 69 | # This gets set (for now) in $^H as well as in %^H, | ||||
| 70 | # for runtime speed of the uc/lc/ucfirst/lcfirst functions. | ||||
| 71 | # See HINT_UNI_8_BIT in perl.h. | ||||
| 72 | 1 | 0s | our $hint_uni8bit = 0x00000800; | ||
| 73 | |||||
| 74 | # TODO: | ||||
| 75 | # - think about versioned features (use feature switch => 2) | ||||
| 76 | |||||
| 77 | =head1 NAME | ||||
| 78 | |||||
| 79 | feature - Perl pragma to enable new features | ||||
| 80 | |||||
| 81 | =head1 SYNOPSIS | ||||
| 82 | |||||
| 83 | use feature qw(say switch); | ||||
| 84 | given ($foo) { | ||||
| 85 | when (1) { say "\$foo == 1" } | ||||
| 86 | when ([2,3]) { say "\$foo == 2 || \$foo == 3" } | ||||
| 87 | when (/^a[bc]d$/) { say "\$foo eq 'abd' || \$foo eq 'acd'" } | ||||
| 88 | when ($_ > 100) { say "\$foo > 100" } | ||||
| 89 | default { say "None of the above" } | ||||
| 90 | } | ||||
| 91 | |||||
| 92 | use feature ':5.10'; # loads all features available in perl 5.10 | ||||
| 93 | |||||
| 94 | use v5.10; # implicitly loads :5.10 feature bundle | ||||
| 95 | |||||
| 96 | =head1 DESCRIPTION | ||||
| 97 | |||||
| 98 | It is usually impossible to add new syntax to Perl without breaking | ||||
| 99 | some existing programs. This pragma provides a way to minimize that | ||||
| 100 | risk. New syntactic constructs, or new semantic meanings to older | ||||
| 101 | constructs, can be enabled by C<use feature 'foo'>, and will be parsed | ||||
| 102 | only when the appropriate feature pragma is in scope. (Nevertheless, the | ||||
| 103 | C<CORE::> prefix provides access to all Perl keywords, regardless of this | ||||
| 104 | pragma.) | ||||
| 105 | |||||
| 106 | =head2 Lexical effect | ||||
| 107 | |||||
| 108 | Like other pragmas (C<use strict>, for example), features have a lexical | ||||
| 109 | effect. C<use feature qw(foo)> will only make the feature "foo" available | ||||
| 110 | from that point to the end of the enclosing block. | ||||
| 111 | |||||
| 112 | { | ||||
| 113 | use feature 'say'; | ||||
| 114 | say "say is available here"; | ||||
| 115 | } | ||||
| 116 | print "But not here.\n"; | ||||
| 117 | |||||
| 118 | =head2 C<no feature> | ||||
| 119 | |||||
| 120 | Features can also be turned off by using C<no feature "foo">. This too | ||||
| 121 | has lexical effect. | ||||
| 122 | |||||
| 123 | use feature 'say'; | ||||
| 124 | say "say is available here"; | ||||
| 125 | { | ||||
| 126 | no feature 'say'; | ||||
| 127 | print "But not here.\n"; | ||||
| 128 | } | ||||
| 129 | say "Yet it is here."; | ||||
| 130 | |||||
| 131 | C<no feature> with no features specified will reset to the default group. To | ||||
| 132 | disable I<all> features (an unusual request!) use C<no feature ':all'>. | ||||
| 133 | |||||
| 134 | =head1 AVAILABLE FEATURES | ||||
| 135 | |||||
| 136 | =head2 The 'say' feature | ||||
| 137 | |||||
| 138 | C<use feature 'say'> tells the compiler to enable the Perl 6 style | ||||
| 139 | C<say> function. | ||||
| 140 | |||||
| 141 | See L<perlfunc/say> for details. | ||||
| 142 | |||||
| 143 | This feature is available starting with Perl 5.10. | ||||
| 144 | |||||
| 145 | =head2 The 'state' feature | ||||
| 146 | |||||
| 147 | C<use feature 'state'> tells the compiler to enable C<state> | ||||
| 148 | variables. | ||||
| 149 | |||||
| 150 | See L<perlsub/"Persistent Private Variables"> for details. | ||||
| 151 | |||||
| 152 | This feature is available starting with Perl 5.10. | ||||
| 153 | |||||
| 154 | =head2 The 'switch' feature | ||||
| 155 | |||||
| 156 | B<WARNING>: Because the L<smartmatch operator|perlop/"Smartmatch Operator"> is | ||||
| 157 | experimental, Perl will warn when you use this feature, unless you have | ||||
| 158 | explicitly disabled the warning: | ||||
| 159 | |||||
| 160 | no warnings "experimental::smartmatch"; | ||||
| 161 | |||||
| 162 | C<use feature 'switch'> tells the compiler to enable the Perl 6 | ||||
| 163 | given/when construct. | ||||
| 164 | |||||
| 165 | See L<perlsyn/"Switch Statements"> for details. | ||||
| 166 | |||||
| 167 | This feature is available starting with Perl 5.10. | ||||
| 168 | |||||
| 169 | =head2 The 'unicode_strings' feature | ||||
| 170 | |||||
| 171 | C<use feature 'unicode_strings'> tells the compiler to use Unicode rules | ||||
| 172 | in all string operations executed within its scope (unless they are also | ||||
| 173 | within the scope of either C<use locale> or C<use bytes>). The same applies | ||||
| 174 | to all regular expressions compiled within the scope, even if executed outside | ||||
| 175 | it. It does not change the internal representation of strings, but only how | ||||
| 176 | they are interpreted. | ||||
| 177 | |||||
| 178 | C<no feature 'unicode_strings'> tells the compiler to use the traditional | ||||
| 179 | Perl rules wherein the native character set rules is used unless it is | ||||
| 180 | clear to Perl that Unicode is desired. This can lead to some surprises | ||||
| 181 | when the behavior suddenly changes. (See | ||||
| 182 | L<perlunicode/The "Unicode Bug"> for details.) For this reason, if you are | ||||
| 183 | potentially using Unicode in your program, the | ||||
| 184 | C<use feature 'unicode_strings'> subpragma is B<strongly> recommended. | ||||
| 185 | |||||
| 186 | This feature is available starting with Perl 5.12; was almost fully | ||||
| 187 | implemented in Perl 5.14; and extended in Perl 5.16 to cover C<quotemeta>; | ||||
| 188 | was extended further in Perl 5.26 to cover L<the range | ||||
| 189 | operator|perlop/Range Operators>; and was extended again in Perl 5.28 to | ||||
| 190 | cover L<special-cased whitespace splitting|perlfunc/split>. | ||||
| 191 | |||||
| 192 | =head2 The 'unicode_eval' and 'evalbytes' features | ||||
| 193 | |||||
| 194 | Together, these two features are intended to replace the legacy string | ||||
| 195 | C<eval> function, which behaves problematically in some instances. They are | ||||
| 196 | available starting with Perl 5.16, and are enabled by default by a | ||||
| 197 | S<C<use 5.16>> or higher declaration. | ||||
| 198 | |||||
| 199 | C<unicode_eval> changes the behavior of plain string C<eval> to work more | ||||
| 200 | consistently, especially in the Unicode world. Certain (mis)behaviors | ||||
| 201 | couldn't be changed without breaking some things that had come to rely on | ||||
| 202 | them, so the feature can be enabled and disabled. Details are at | ||||
| 203 | L<perlfunc/Under the "unicode_eval" feature>. | ||||
| 204 | |||||
| 205 | C<evalbytes> is like string C<eval>, but operating on a byte stream that is | ||||
| 206 | not UTF-8 encoded. Details are at L<perlfunc/evalbytes EXPR>. Without a | ||||
| 207 | S<C<use feature 'evalbytes'>> nor a S<C<use v5.16>> (or higher) declaration in | ||||
| 208 | the current scope, you can still access it by instead writing | ||||
| 209 | C<CORE::evalbytes>. | ||||
| 210 | |||||
| 211 | =head2 The 'current_sub' feature | ||||
| 212 | |||||
| 213 | This provides the C<__SUB__> token that returns a reference to the current | ||||
| 214 | subroutine or C<undef> outside of a subroutine. | ||||
| 215 | |||||
| 216 | This feature is available starting with Perl 5.16. | ||||
| 217 | |||||
| 218 | =head2 The 'array_base' feature | ||||
| 219 | |||||
| 220 | This feature supported the legacy C<$[> variable. See L<perlvar/$[>. | ||||
| 221 | It was on by default but disabled under C<use v5.16> (see | ||||
| 222 | L</IMPLICIT LOADING>, below) and unavailable since perl 5.30. | ||||
| 223 | |||||
| 224 | This feature is available under this name starting with Perl 5.16. In | ||||
| 225 | previous versions, it was simply on all the time, and this pragma knew | ||||
| 226 | nothing about it. | ||||
| 227 | |||||
| 228 | =head2 The 'fc' feature | ||||
| 229 | |||||
| 230 | C<use feature 'fc'> tells the compiler to enable the C<fc> function, | ||||
| 231 | which implements Unicode casefolding. | ||||
| 232 | |||||
| 233 | See L<perlfunc/fc> for details. | ||||
| 234 | |||||
| 235 | This feature is available from Perl 5.16 onwards. | ||||
| 236 | |||||
| 237 | =head2 The 'lexical_subs' feature | ||||
| 238 | |||||
| 239 | In Perl versions prior to 5.26, this feature enabled | ||||
| 240 | declaration of subroutines via C<my sub foo>, C<state sub foo> | ||||
| 241 | and C<our sub foo> syntax. See L<perlsub/Lexical Subroutines> for details. | ||||
| 242 | |||||
| 243 | This feature is available from Perl 5.18 onwards. From Perl 5.18 to 5.24, | ||||
| 244 | it was classed as experimental, and Perl emitted a warning for its | ||||
| 245 | usage, except when explicitly disabled: | ||||
| 246 | |||||
| 247 | no warnings "experimental::lexical_subs"; | ||||
| 248 | |||||
| 249 | As of Perl 5.26, use of this feature no longer triggers a warning, though | ||||
| 250 | the C<experimental::lexical_subs> warning category still exists (for | ||||
| 251 | compatibility with code that disables it). In addition, this syntax is | ||||
| 252 | not only no longer experimental, but it is enabled for all Perl code, | ||||
| 253 | regardless of what feature declarations are in scope. | ||||
| 254 | |||||
| 255 | =head2 The 'postderef' and 'postderef_qq' features | ||||
| 256 | |||||
| 257 | The 'postderef_qq' feature extends the applicability of L<postfix | ||||
| 258 | dereference syntax|perlref/Postfix Dereference Syntax> so that postfix array | ||||
| 259 | and scalar dereference are available in double-quotish interpolations. For | ||||
| 260 | example, it makes the following two statements equivalent: | ||||
| 261 | |||||
| 262 | my $s = "[@{ $h->{a} }]"; | ||||
| 263 | my $s = "[$h->{a}->@*]"; | ||||
| 264 | |||||
| 265 | This feature is available from Perl 5.20 onwards. In Perl 5.20 and 5.22, it | ||||
| 266 | was classed as experimental, and Perl emitted a warning for its | ||||
| 267 | usage, except when explicitly disabled: | ||||
| 268 | |||||
| 269 | no warnings "experimental::postderef"; | ||||
| 270 | |||||
| 271 | As of Perl 5.24, use of this feature no longer triggers a warning, though | ||||
| 272 | the C<experimental::postderef> warning category still exists (for | ||||
| 273 | compatibility with code that disables it). | ||||
| 274 | |||||
| 275 | The 'postderef' feature was used in Perl 5.20 and Perl 5.22 to enable | ||||
| 276 | postfix dereference syntax outside double-quotish interpolations. In those | ||||
| 277 | versions, using it triggered the C<experimental::postderef> warning in the | ||||
| 278 | same way as the 'postderef_qq' feature did. As of Perl 5.24, this syntax is | ||||
| 279 | not only no longer experimental, but it is enabled for all Perl code, | ||||
| 280 | regardless of what feature declarations are in scope. | ||||
| 281 | |||||
| 282 | =head2 The 'signatures' feature | ||||
| 283 | |||||
| 284 | B<WARNING>: This feature is still experimental and the implementation may | ||||
| 285 | change in future versions of Perl. For this reason, Perl will | ||||
| 286 | warn when you use the feature, unless you have explicitly disabled the | ||||
| 287 | warning: | ||||
| 288 | |||||
| 289 | no warnings "experimental::signatures"; | ||||
| 290 | |||||
| 291 | This enables unpacking of subroutine arguments into lexical variables | ||||
| 292 | by syntax such as | ||||
| 293 | |||||
| 294 | sub foo ($left, $right) { | ||||
| 295 | return $left + $right; | ||||
| 296 | } | ||||
| 297 | |||||
| 298 | See L<perlsub/Signatures> for details. | ||||
| 299 | |||||
| 300 | This feature is available from Perl 5.20 onwards. | ||||
| 301 | |||||
| 302 | =head2 The 'refaliasing' feature | ||||
| 303 | |||||
| 304 | B<WARNING>: This feature is still experimental and the implementation may | ||||
| 305 | change in future versions of Perl. For this reason, Perl will | ||||
| 306 | warn when you use the feature, unless you have explicitly disabled the | ||||
| 307 | warning: | ||||
| 308 | |||||
| 309 | no warnings "experimental::refaliasing"; | ||||
| 310 | |||||
| 311 | This enables aliasing via assignment to references: | ||||
| 312 | |||||
| 313 | \$a = \$b; # $a and $b now point to the same scalar | ||||
| 314 | \@a = \@b; # to the same array | ||||
| 315 | \%a = \%b; | ||||
| 316 | \&a = \&b; | ||||
| 317 | foreach \%hash (@array_of_hash_refs) { | ||||
| 318 | ... | ||||
| 319 | } | ||||
| 320 | |||||
| 321 | See L<perlref/Assigning to References> for details. | ||||
| 322 | |||||
| 323 | This feature is available from Perl 5.22 onwards. | ||||
| 324 | |||||
| 325 | =head2 The 'bitwise' feature | ||||
| 326 | |||||
| 327 | This makes the four standard bitwise operators (C<& | ^ ~>) treat their | ||||
| 328 | operands consistently as numbers, and introduces four new dotted operators | ||||
| 329 | (C<&. |. ^. ~.>) that treat their operands consistently as strings. The | ||||
| 330 | same applies to the assignment variants (C<&= |= ^= &.= |.= ^.=>). | ||||
| 331 | |||||
| 332 | See L<perlop/Bitwise String Operators> for details. | ||||
| 333 | |||||
| 334 | This feature is available from Perl 5.22 onwards. Starting in Perl 5.28, | ||||
| 335 | C<use v5.28> will enable the feature. Before 5.28, it was still | ||||
| 336 | experimental and would emit a warning in the "experimental::bitwise" | ||||
| 337 | category. | ||||
| 338 | |||||
| 339 | =head2 The 'declared_refs' feature | ||||
| 340 | |||||
| 341 | B<WARNING>: This feature is still experimental and the implementation may | ||||
| 342 | change in future versions of Perl. For this reason, Perl will | ||||
| 343 | warn when you use the feature, unless you have explicitly disabled the | ||||
| 344 | warning: | ||||
| 345 | |||||
| 346 | no warnings "experimental::declared_refs"; | ||||
| 347 | |||||
| 348 | This allows a reference to a variable to be declared with C<my>, C<state>, | ||||
| 349 | our C<our>, or localized with C<local>. It is intended mainly for use in | ||||
| 350 | conjunction with the "refaliasing" feature. See L<perlref/Declaring a | ||||
| 351 | Reference to a Variable> for examples. | ||||
| 352 | |||||
| 353 | This feature is available from Perl 5.26 onwards. | ||||
| 354 | |||||
| 355 | =head2 The 'isa' feature | ||||
| 356 | |||||
| 357 | This allows the use of the C<isa> infix operator, which tests whether the | ||||
| 358 | scalar given by the left operand is an object of the class given by the | ||||
| 359 | right operand. See L<perlop/Class Instance Operator> for more details. | ||||
| 360 | |||||
| 361 | This feature is available from Perl 5.32 onwards. | ||||
| 362 | |||||
| 363 | =head2 The 'indirect' feature | ||||
| 364 | |||||
| 365 | This feature allows the use of L<indirect object | ||||
| 366 | syntax|perlobj/Indirect Object Syntax> for method calls, e.g. C<new | ||||
| 367 | Foo 1, 2;>. It is enabled by default, but can be turned off to | ||||
| 368 | disallow indirect object syntax. | ||||
| 369 | |||||
| 370 | This feature is available under this name from Perl 5.32 onwards. In | ||||
| 371 | previous versions, it was simply on all the time. To disallow (or | ||||
| 372 | warn on) indirect object syntax on older Perls, see the L<indirect> | ||||
| 373 | CPAN module. | ||||
| 374 | |||||
| 375 | =head1 FEATURE BUNDLES | ||||
| 376 | |||||
| 377 | It's possible to load multiple features together, using | ||||
| 378 | a I<feature bundle>. The name of a feature bundle is prefixed with | ||||
| 379 | a colon, to distinguish it from an actual feature. | ||||
| 380 | |||||
| 381 | use feature ":5.10"; | ||||
| 382 | |||||
| 383 | The following feature bundles are available: | ||||
| 384 | |||||
| 385 | bundle features included | ||||
| 386 | --------- ----------------- | ||||
| 387 | :default indirect | ||||
| 388 | |||||
| 389 | :5.10 say state switch indirect | ||||
| 390 | |||||
| 391 | :5.12 say state switch unicode_strings indirect | ||||
| 392 | |||||
| 393 | :5.14 say state switch unicode_strings indirect | ||||
| 394 | |||||
| 395 | :5.16 say state switch unicode_strings | ||||
| 396 | unicode_eval evalbytes current_sub fc | ||||
| 397 | indirect | ||||
| 398 | |||||
| 399 | :5.18 say state switch unicode_strings | ||||
| 400 | unicode_eval evalbytes current_sub fc | ||||
| 401 | indirect | ||||
| 402 | |||||
| 403 | :5.20 say state switch unicode_strings | ||||
| 404 | unicode_eval evalbytes current_sub fc | ||||
| 405 | indirect | ||||
| 406 | |||||
| 407 | :5.22 say state switch unicode_strings | ||||
| 408 | unicode_eval evalbytes current_sub fc | ||||
| 409 | indirect | ||||
| 410 | |||||
| 411 | :5.24 say state switch unicode_strings | ||||
| 412 | unicode_eval evalbytes current_sub fc | ||||
| 413 | postderef_qq indirect | ||||
| 414 | |||||
| 415 | :5.26 say state switch unicode_strings | ||||
| 416 | unicode_eval evalbytes current_sub fc | ||||
| 417 | postderef_qq indirect | ||||
| 418 | |||||
| 419 | :5.28 say state switch unicode_strings | ||||
| 420 | unicode_eval evalbytes current_sub fc | ||||
| 421 | postderef_qq bitwise indirect | ||||
| 422 | |||||
| 423 | :5.30 say state switch unicode_strings | ||||
| 424 | unicode_eval evalbytes current_sub fc | ||||
| 425 | postderef_qq bitwise indirect | ||||
| 426 | |||||
| 427 | :5.32 say state switch unicode_strings | ||||
| 428 | unicode_eval evalbytes current_sub fc | ||||
| 429 | postderef_qq bitwise indirect | ||||
| 430 | |||||
| 431 | The C<:default> bundle represents the feature set that is enabled before | ||||
| 432 | any C<use feature> or C<no feature> declaration. | ||||
| 433 | |||||
| 434 | Specifying sub-versions such as the C<0> in C<5.14.0> in feature bundles has | ||||
| 435 | no effect. Feature bundles are guaranteed to be the same for all sub-versions. | ||||
| 436 | |||||
| 437 | use feature ":5.14.0"; # same as ":5.14" | ||||
| 438 | use feature ":5.14.1"; # same as ":5.14" | ||||
| 439 | |||||
| 440 | =head1 IMPLICIT LOADING | ||||
| 441 | |||||
| 442 | Instead of loading feature bundles by name, it is easier to let Perl do | ||||
| 443 | implicit loading of a feature bundle for you. | ||||
| 444 | |||||
| 445 | There are two ways to load the C<feature> pragma implicitly: | ||||
| 446 | |||||
| 447 | =over 4 | ||||
| 448 | |||||
| 449 | =item * | ||||
| 450 | |||||
| 451 | By using the C<-E> switch on the Perl command-line instead of C<-e>. | ||||
| 452 | That will enable the feature bundle for that version of Perl in the | ||||
| 453 | main compilation unit (that is, the one-liner that follows C<-E>). | ||||
| 454 | |||||
| 455 | =item * | ||||
| 456 | |||||
| 457 | By explicitly requiring a minimum Perl version number for your program, with | ||||
| 458 | the C<use VERSION> construct. That is, | ||||
| 459 | |||||
| 460 | use v5.10.0; | ||||
| 461 | |||||
| 462 | will do an implicit | ||||
| 463 | |||||
| 464 | no feature ':all'; | ||||
| 465 | use feature ':5.10'; | ||||
| 466 | |||||
| 467 | and so on. Note how the trailing sub-version | ||||
| 468 | is automatically stripped from the | ||||
| 469 | version. | ||||
| 470 | |||||
| 471 | But to avoid portability warnings (see L<perlfunc/use>), you may prefer: | ||||
| 472 | |||||
| 473 | use 5.010; | ||||
| 474 | |||||
| 475 | with the same effect. | ||||
| 476 | |||||
| 477 | If the required version is older than Perl 5.10, the ":default" feature | ||||
| 478 | bundle is automatically loaded instead. | ||||
| 479 | |||||
| 480 | Unlike C<use feature ":5.12">, saying C<use v5.12> (or any higher version) | ||||
| 481 | also does the equivalent of C<use strict>; see L<perlfunc/use> for details. | ||||
| 482 | |||||
| 483 | =back | ||||
| 484 | |||||
| 485 | =cut | ||||
| 486 | |||||
| 487 | # spent 24µs (2+22) within feature::import which was called:
# once (2µs+22µs) by experimental::_enable at line 61 of experimental.pm | ||||
| 488 | 1 | 100ns | shift; | ||
| 489 | |||||
| 490 | 1 | 100ns | if (!@_) { | ||
| 491 | croak("No features specified"); | ||||
| 492 | } | ||||
| 493 | |||||
| 494 | 1 | 2µs | 1 | 22µs | __common(1, @_); # spent 22µs making 1 call to feature::__common |
| 495 | } | ||||
| 496 | |||||
| 497 | sub unimport { | ||||
| 498 | shift; | ||||
| 499 | |||||
| 500 | # A bare C<no feature> should reset to the default bundle | ||||
| 501 | if (!@_) { | ||||
| 502 | $^H &= ~($hint_uni8bit|$hint_mask); | ||||
| 503 | return; | ||||
| 504 | } | ||||
| 505 | |||||
| 506 | __common(0, @_); | ||||
| 507 | } | ||||
| 508 | |||||
| 509 | |||||
| 510 | # spent 22µs within feature::__common which was called:
# once (22µs+0s) by feature::import at line 494 | ||||
| 511 | 1 | 200ns | my $import = shift; | ||
| 512 | 1 | 400ns | my $bundle_number = $^H & $hint_mask; | ||
| 513 | my $features = $bundle_number != $hint_mask | ||||
| 514 | 1 | 500ns | && $feature_bundle{$hint_bundles[$bundle_number >> $hint_shift]}; | ||
| 515 | 1 | 200ns | if ($features) { | ||
| 516 | # Features are enabled implicitly via bundle hints. | ||||
| 517 | # Delete any keys that may be left over from last time. | ||||
| 518 | 1 | 8µs | delete @^H{ values(%feature) }; | ||
| 519 | 1 | 400ns | $^H |= $hint_mask; | ||
| 520 | 1 | 300ns | for (@$features) { | ||
| 521 | 11 | 7µs | $^H{$feature{$_}} = 1; | ||
| 522 | 11 | 1µs | $^H |= $hint_uni8bit if $_ eq 'unicode_strings'; | ||
| 523 | } | ||||
| 524 | } | ||||
| 525 | 1 | 2µs | while (@_) { | ||
| 526 | 1 | 100ns | my $name = shift; | ||
| 527 | 1 | 1µs | if (substr($name, 0, 1) eq ":") { | ||
| 528 | my $v = substr($name, 1); | ||||
| 529 | if (!exists $feature_bundle{$v}) { | ||||
| 530 | $v =~ s/^([0-9]+)\.([0-9]+).[0-9]+$/$1.$2/; | ||||
| 531 | if (!exists $feature_bundle{$v}) { | ||||
| 532 | unknown_feature_bundle(substr($name, 1)); | ||||
| 533 | } | ||||
| 534 | } | ||||
| 535 | unshift @_, @{$feature_bundle{$v}}; | ||||
| 536 | next; | ||||
| 537 | } | ||||
| 538 | 1 | 100ns | if (!exists $feature{$name}) { | ||
| 539 | if (exists $noops{$name}) { | ||||
| 540 | next; | ||||
| 541 | } | ||||
| 542 | if (!$import && exists $removed{$name}) { | ||||
| 543 | next; | ||||
| 544 | } | ||||
| 545 | unknown_feature($name); | ||||
| 546 | } | ||||
| 547 | 1 | 400ns | if ($import) { | ||
| 548 | 1 | 700ns | $^H{$feature{$name}} = 1; | ||
| 549 | 1 | 100ns | $^H |= $hint_uni8bit if $name eq 'unicode_strings'; | ||
| 550 | } else { | ||||
| 551 | delete $^H{$feature{$name}}; | ||||
| 552 | $^H &= ~ $hint_uni8bit if $name eq 'unicode_strings'; | ||||
| 553 | } | ||||
| 554 | } | ||||
| 555 | } | ||||
| 556 | |||||
| 557 | sub unknown_feature { | ||||
| 558 | my $feature = shift; | ||||
| 559 | croak(sprintf('Feature "%s" is not supported by Perl %vd', | ||||
| 560 | $feature, $^V)); | ||||
| 561 | } | ||||
| 562 | |||||
| 563 | sub unknown_feature_bundle { | ||||
| 564 | my $feature = shift; | ||||
| 565 | croak(sprintf('Feature bundle "%s" is not supported by Perl %vd', | ||||
| 566 | $feature, $^V)); | ||||
| 567 | } | ||||
| 568 | |||||
| 569 | sub croak { | ||||
| 570 | require Carp; | ||||
| 571 | Carp::croak(@_); | ||||
| 572 | } | ||||
| 573 | |||||
| 574 | 1 | 11µs | 1; | ||
| 575 | |||||
| 576 | # ex: set ro: |