Filename | /home/hinrik/perl5/perlbrew/perls/perl-5.13.5/lib/5.13.5/feature.pm |
Statements | Executed 292 statements in 915µs |
Calls | P | F | Exclusive Time |
Inclusive Time |
Subroutine |
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11 | 11 | 11 | 725µs | 844µs | import | feature::
11 | 1 | 1 | 77µs | 77µs | CORE:subst (opcode) | feature::
22 | 1 | 1 | 42µs | 42µs | CORE:substcont (opcode) | feature::
0 | 0 | 0 | 0s | 0s | croak | feature::
0 | 0 | 0 | 0s | 0s | unimport | feature::
0 | 0 | 0 | 0s | 0s | unknown_feature | feature::
0 | 0 | 0 | 0s | 0s | unknown_feature_bundle | feature::
Line | State ments |
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1 | package feature; | ||||
2 | |||||
3 | 1 | 2µs | our $VERSION = '1.18'; | ||
4 | |||||
5 | # (feature name) => (internal name, used in %^H) | ||||
6 | 1 | 23µs | 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 | 1µs | our $hint_uni8bit = 0x00000800; | ||
17 | |||||
18 | # NB. the latest bundle must be loaded by the -E switch (see toke.c) | ||||
19 | |||||
20 | 1 | 9µs | 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 | 2µs | $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 844µs (725+119) within feature::import which was called 11 times, avg 77µs/call:
# once (82µs+16µs) by Hailo::Engine::Default::BEGIN@9.11 at line 9 of Hailo/Engine/Default.pm
# once (72µs+16µs) by Hailo::Storage::Schema::BEGIN@9.8 at line 9 of Hailo/Storage/Schema.pm
# once (74µs+11µs) by Hailo::Storage::SQLite::BEGIN@9.5 at line 9 of Hailo/Storage/SQLite.pm
# once (73µs+11µs) by Hailo::Role::Engine::BEGIN@9.12 at line 9 of Hailo/Role/Engine.pm
# once (67µs+12µs) by main::BEGIN@5.1 at line 5 of reply.pl
# once (64µs+10µs) by Hailo::Role::Tokenizer::BEGIN@9.14 at line 9 of Hailo/Role/Tokenizer.pm
# once (63µs+9µs) by Hailo::Storage::BEGIN@9.6 at line 9 of Hailo/Storage.pm
# once (60µs+10µs) by Hailo::Role::Storage::BEGIN@9.10 at line 9 of Hailo/Role/Storage.pm
# once (61µs+8µs) by Hailo::Role::Arguments::BEGIN@9.9 at line 9 of Hailo/Role/Arguments.pm
# once (58µs+9µs) by Hailo::Tokenizer::Words::BEGIN@9.13 at line 9 of Hailo/Tokenizer/Words.pm
# once (52µs+7µs) by Hailo::BEGIN@9.2 at line 9 of Hailo.pm | ||||
162 | 33 | 114µs | my $class = shift; | ||
163 | if (@_ == 0) { | ||||
164 | croak("No features specified"); | ||||
165 | } | ||||
166 | while (@_) { | ||||
167 | 187 | 355µs | my $name = shift(@_); | ||
168 | 44 | 113µs | if (substr($name, 0, 1) eq ":") { | ||
169 | my $v = substr($name, 1); | ||||
170 | 22 | 289µs | if (!exists $feature_bundle{$v}) { | ||
171 | 33 | 119µs | $v =~ s/^([0-9]+)\.([0-9]+).[0-9]+$/$1.$2/; # spent 77µs making 11 calls to feature::CORE:subst, avg 7µs/call
# spent 42µs making 22 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 | 7µs | 1; | ||
# spent 77µs within feature::CORE:subst which was called 11 times, avg 7µs/call:
# 11 times (77µs+0s) by feature::import at line 171, avg 7µs/call | |||||
# spent 42µs within feature::CORE:substcont which was called 22 times, avg 2µs/call:
# 22 times (42µs+0s) by feature::import at line 171, avg 2µs/call |