| Filename | /home/hinrik/perl5/perlbrew/perls/perl-5.13.5/lib/5.13.5/feature.pm |
| Statements | Executed 318 statements in 1.08ms |
| Calls | P | F | Exclusive Time |
Inclusive Time |
Subroutine |
|---|---|---|---|---|---|
| 12 | 12 | 12 | 834µs | 982µs | feature::import |
| 12 | 1 | 1 | 91µs | 91µs | feature::CORE:subst (opcode) |
| 24 | 1 | 1 | 57µs | 57µs | feature::CORE:substcont (opcode) |
| 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 | package feature; | ||||
| 2 | |||||
| 3 | 1 | 4µs | our $VERSION = '1.18'; | ||
| 4 | |||||
| 5 | # (feature name) => (internal name, used in %^H) | ||||
| 6 | 1 | 9µs | my %feature = ( | ||
| 7 | switch => 'feature_switch', | ||||
| 8 | say => "feature_say", | ||||
| 9 | state => "feature_state", | ||||
| 10 | unicode_strings => "feature_unicode", | ||||
| 11 | ); | ||||
| 12 | |||||
| 13 | # This gets set (for now) in $^H as well as in %^H, | ||||
| 14 | # for runtime speed of the uc/lc/ucfirst/lcfirst functions. | ||||
| 15 | # See HINT_UNI_8_BIT in perl.h. | ||||
| 16 | 1 | 2µs | our $hint_uni8bit = 0x00000800; | ||
| 17 | |||||
| 18 | # NB. the latest bundle must be loaded by the -E switch (see toke.c) | ||||
| 19 | |||||
| 20 | 1 | 23µs | my %feature_bundle = ( | ||
| 21 | "5.10" => [qw(switch say state)], | ||||
| 22 | "5.11" => [qw(switch say state unicode_strings)], | ||||
| 23 | "5.12" => [qw(switch say state unicode_strings)], | ||||
| 24 | "5.13" => [qw(switch say state unicode_strings)], | ||||
| 25 | ); | ||||
| 26 | |||||
| 27 | # special case | ||||
| 28 | 1 | 3µs | $feature_bundle{"5.9.5"} = $feature_bundle{"5.10"}; | ||
| 29 | |||||
| 30 | # TODO: | ||||
| 31 | # - think about versioned features (use feature switch => 2) | ||||
| 32 | |||||
| 33 | =head1 NAME | ||||
| 34 | |||||
| 35 | feature - Perl pragma to enable new features | ||||
| 36 | |||||
| 37 | =head1 SYNOPSIS | ||||
| 38 | |||||
| 39 | use feature qw(switch say); | ||||
| 40 | given ($foo) { | ||||
| 41 | when (1) { say "\$foo == 1" } | ||||
| 42 | when ([2,3]) { say "\$foo == 2 || \$foo == 3" } | ||||
| 43 | when (/^a[bc]d$/) { say "\$foo eq 'abd' || \$foo eq 'acd'" } | ||||
| 44 | when ($_ > 100) { say "\$foo > 100" } | ||||
| 45 | default { say "None of the above" } | ||||
| 46 | } | ||||
| 47 | |||||
| 48 | use feature ':5.10'; # loads all features available in perl 5.10 | ||||
| 49 | |||||
| 50 | =head1 DESCRIPTION | ||||
| 51 | |||||
| 52 | It is usually impossible to add new syntax to Perl without breaking | ||||
| 53 | some existing programs. This pragma provides a way to minimize that | ||||
| 54 | risk. New syntactic constructs, or new semantic meanings to older | ||||
| 55 | constructs, can be enabled by C<use feature 'foo'>, and will be parsed | ||||
| 56 | only when the appropriate feature pragma is in scope. | ||||
| 57 | |||||
| 58 | =head2 Lexical effect | ||||
| 59 | |||||
| 60 | Like other pragmas (C<use strict>, for example), features have a lexical | ||||
| 61 | effect. C<use feature qw(foo)> will only make the feature "foo" available | ||||
| 62 | from that point to the end of the enclosing block. | ||||
| 63 | |||||
| 64 | { | ||||
| 65 | use feature 'say'; | ||||
| 66 | say "say is available here"; | ||||
| 67 | } | ||||
| 68 | print "But not here.\n"; | ||||
| 69 | |||||
| 70 | =head2 C<no feature> | ||||
| 71 | |||||
| 72 | Features can also be turned off by using C<no feature "foo">. This too | ||||
| 73 | has lexical effect. | ||||
| 74 | |||||
| 75 | use feature 'say'; | ||||
| 76 | say "say is available here"; | ||||
| 77 | { | ||||
| 78 | no feature 'say'; | ||||
| 79 | print "But not here.\n"; | ||||
| 80 | } | ||||
| 81 | say "Yet it is here."; | ||||
| 82 | |||||
| 83 | C<no feature> with no features specified will turn off all features. | ||||
| 84 | |||||
| 85 | =head2 The 'switch' feature | ||||
| 86 | |||||
| 87 | C<use feature 'switch'> tells the compiler to enable the Perl 6 | ||||
| 88 | given/when construct. | ||||
| 89 | |||||
| 90 | See L<perlsyn/"Switch statements"> for details. | ||||
| 91 | |||||
| 92 | =head2 The 'say' feature | ||||
| 93 | |||||
| 94 | C<use feature 'say'> tells the compiler to enable the Perl 6 | ||||
| 95 | C<say> function. | ||||
| 96 | |||||
| 97 | See L<perlfunc/say> for details. | ||||
| 98 | |||||
| 99 | =head2 the 'state' feature | ||||
| 100 | |||||
| 101 | C<use feature 'state'> tells the compiler to enable C<state> | ||||
| 102 | variables. | ||||
| 103 | |||||
| 104 | See L<perlsub/"Persistent Private Variables"> for details. | ||||
| 105 | |||||
| 106 | =head2 the 'unicode_strings' feature | ||||
| 107 | |||||
| 108 | C<use feature 'unicode_strings'> tells the compiler to treat | ||||
| 109 | all strings outside of C<use locale> and C<use bytes> as Unicode. It is | ||||
| 110 | available starting with Perl 5.11.3, but is not fully implemented. | ||||
| 111 | |||||
| 112 | See L<perlunicode/The "Unicode Bug"> for details. | ||||
| 113 | |||||
| 114 | =head1 FEATURE BUNDLES | ||||
| 115 | |||||
| 116 | It's possible to load a whole slew of features in one go, using | ||||
| 117 | a I<feature bundle>. The name of a feature bundle is prefixed with | ||||
| 118 | a colon, to distinguish it from an actual feature. At present, the | ||||
| 119 | only feature bundle is C<use feature ":5.10"> which is equivalent | ||||
| 120 | to C<use feature qw(switch say state)>. | ||||
| 121 | |||||
| 122 | Specifying sub-versions such as the C<0> in C<5.10.0> in feature bundles has | ||||
| 123 | no effect: feature bundles are guaranteed to be the same for all sub-versions. | ||||
| 124 | |||||
| 125 | =head1 IMPLICIT LOADING | ||||
| 126 | |||||
| 127 | There are two ways to load the C<feature> pragma implicitly : | ||||
| 128 | |||||
| 129 | =over 4 | ||||
| 130 | |||||
| 131 | =item * | ||||
| 132 | |||||
| 133 | By using the C<-E> switch on the command-line instead of C<-e>. It enables | ||||
| 134 | all available features in the main compilation unit (that is, the one-liner.) | ||||
| 135 | |||||
| 136 | =item * | ||||
| 137 | |||||
| 138 | By requiring explicitly a minimal Perl version number for your program, with | ||||
| 139 | the C<use VERSION> construct, and when the version is higher than or equal to | ||||
| 140 | 5.10.0. That is, | ||||
| 141 | |||||
| 142 | use 5.10.0; | ||||
| 143 | |||||
| 144 | will do an implicit | ||||
| 145 | |||||
| 146 | use feature ':5.10'; | ||||
| 147 | |||||
| 148 | and so on. Note how the trailing sub-version is automatically stripped from the | ||||
| 149 | version. | ||||
| 150 | |||||
| 151 | But to avoid portability warnings (see L<perlfunc/use>), you may prefer: | ||||
| 152 | |||||
| 153 | use 5.010; | ||||
| 154 | |||||
| 155 | with the same effect. | ||||
| 156 | |||||
| 157 | =back | ||||
| 158 | |||||
| 159 | =cut | ||||
| 160 | |||||
| 161 | # spent 982µs (834+148) within feature::import which was called 12 times, avg 82µs/call:
# once (160µs+42µs) by hailo::BEGIN@3.1 at line 3 of bin/hailo
# once (65µs+15µs) by Hailo::Storage::Schema::BEGIN@3.13 at line 3 of lib/Hailo/Storage/Schema.pm
# once (66µs+8µs) by Hailo::Storage::BEGIN@3.12 at line 3 of lib/Hailo/Storage.pm
# once (64µs+9µs) by Hailo::Role::Storage::BEGIN@3.15 at line 3 of lib/Hailo/Role/Storage.pm
# once (62µs+10µs) by Hailo::Storage::SQLite::BEGIN@3.11 at line 3 of lib/Hailo/Storage/SQLite.pm
# once (61µs+10µs) by Hailo::BEGIN@3.8 at line 3 of lib/Hailo.pm
# once (62µs+8µs) by Hailo::Engine::Default::BEGIN@3.16 at line 3 of lib/Hailo/Engine/Default.pm
# once (61µs+10µs) by Hailo::Role::Tokenizer::BEGIN@3.19 at line 3 of lib/Hailo/Role/Tokenizer.pm
# once (59µs+10µs) by Hailo::Command::BEGIN@3.2 at line 3 of lib/Hailo/Command.pm
# once (61µs+9µs) by Hailo::Role::Engine::BEGIN@3.17 at line 3 of lib/Hailo/Role/Engine.pm
# once (57µs+9µs) by Hailo::Tokenizer::Words::BEGIN@3.18 at line 3 of lib/Hailo/Tokenizer/Words.pm
# once (57µs+8µs) by Hailo::Role::Arguments::BEGIN@3.14 at line 3 of lib/Hailo/Role/Arguments.pm | ||||
| 162 | 312 | 1.02ms | my $class = shift; | ||
| 163 | if (@_ == 0) { | ||||
| 164 | croak("No features specified"); | ||||
| 165 | } | ||||
| 166 | while (@_) { | ||||
| 167 | my $name = shift(@_); | ||||
| 168 | if (substr($name, 0, 1) eq ":") { | ||||
| 169 | my $v = substr($name, 1); | ||||
| 170 | if (!exists $feature_bundle{$v}) { | ||||
| 171 | 36 | 148µs | $v =~ s/^([0-9]+)\.([0-9]+).[0-9]+$/$1.$2/; # spent 91µs making 12 calls to feature::CORE:subst, avg 8µs/call
# spent 57µs making 24 calls to feature::CORE:substcont, avg 2µs/call | ||
| 172 | if (!exists $feature_bundle{$v}) { | ||||
| 173 | unknown_feature_bundle(substr($name, 1)); | ||||
| 174 | } | ||||
| 175 | } | ||||
| 176 | unshift @_, @{$feature_bundle{$v}}; | ||||
| 177 | next; | ||||
| 178 | } | ||||
| 179 | if (!exists $feature{$name}) { | ||||
| 180 | unknown_feature($name); | ||||
| 181 | } | ||||
| 182 | $^H{$feature{$name}} = 1; | ||||
| 183 | $^H |= $hint_uni8bit if $name eq 'unicode_strings'; | ||||
| 184 | } | ||||
| 185 | } | ||||
| 186 | |||||
| 187 | sub unimport { | ||||
| 188 | my $class = shift; | ||||
| 189 | |||||
| 190 | # A bare C<no feature> should disable *all* features | ||||
| 191 | if (!@_) { | ||||
| 192 | delete @^H{ values(%feature) }; | ||||
| 193 | $^H &= ~ $hint_uni8bit; | ||||
| 194 | return; | ||||
| 195 | } | ||||
| 196 | |||||
| 197 | while (@_) { | ||||
| 198 | my $name = shift; | ||||
| 199 | if (substr($name, 0, 1) eq ":") { | ||||
| 200 | my $v = substr($name, 1); | ||||
| 201 | if (!exists $feature_bundle{$v}) { | ||||
| 202 | $v =~ s/^([0-9]+)\.([0-9]+).[0-9]+$/$1.$2/; | ||||
| 203 | if (!exists $feature_bundle{$v}) { | ||||
| 204 | unknown_feature_bundle(substr($name, 1)); | ||||
| 205 | } | ||||
| 206 | } | ||||
| 207 | unshift @_, @{$feature_bundle{$v}}; | ||||
| 208 | next; | ||||
| 209 | } | ||||
| 210 | if (!exists($feature{$name})) { | ||||
| 211 | unknown_feature($name); | ||||
| 212 | } | ||||
| 213 | else { | ||||
| 214 | delete $^H{$feature{$name}}; | ||||
| 215 | $^H &= ~ $hint_uni8bit if $name eq 'unicode_strings'; | ||||
| 216 | } | ||||
| 217 | } | ||||
| 218 | } | ||||
| 219 | |||||
| 220 | sub unknown_feature { | ||||
| 221 | my $feature = shift; | ||||
| 222 | croak(sprintf('Feature "%s" is not supported by Perl %vd', | ||||
| 223 | $feature, $^V)); | ||||
| 224 | } | ||||
| 225 | |||||
| 226 | sub unknown_feature_bundle { | ||||
| 227 | my $feature = shift; | ||||
| 228 | croak(sprintf('Feature bundle "%s" is not supported by Perl %vd', | ||||
| 229 | $feature, $^V)); | ||||
| 230 | } | ||||
| 231 | |||||
| 232 | sub croak { | ||||
| 233 | require Carp; | ||||
| 234 | Carp::croak(@_); | ||||
| 235 | } | ||||
| 236 | |||||
| 237 | 1 | 22µs | 1; | ||
# spent 91µs within feature::CORE:subst which was called 12 times, avg 8µs/call:
# 12 times (91µs+0s) by feature::import at line 171, avg 8µs/call | |||||
# spent 57µs within feature::CORE:substcont which was called 24 times, avg 2µs/call:
# 24 times (57µs+0s) by feature::import at line 171, avg 2µs/call |