Profile: /opt/wise/lib/perl5/5.10.0/feature.pm

File	/opt/wise/lib/perl5/5.10.0/feature.pm
Statements Executed	90
Total Time	0.000196 seconds

Subroutines — ordered by exclusive time
Calls	P	F	Exclusive Time	Inclusive Time	Subroutine
4	4	4	0.00018	0.00018	feature::	import
0	0	0	0	0	feature::	croak
0	0	0	0	0	feature::	unimport
0	0	0	0	0	feature::	unknown_feature
0	0	0	0	0	feature::	unknown_feature_bundle

Line	Stmts.	Exclusive Time	Avg.	Code
1				package feature;
2
3	1	1.0e-6	1.0e-6	our $VERSION = '1.11';
4
5				# (feature name) => (internal name, used in %^H)
6	1	3.0e-6	3.0e-6	my %feature = (
7				switch => 'feature_switch',
8				say => "feature_say",
9				state => "feature_state",
10				);
11
12	1	5.0e-6	5.0e-6	my %feature_bundle = (
13				"5.10.0" => [qw(switch say state)],
14				);
15
16				# latest version here
17	1	1.6e-5	1.6e-5	$feature_bundle{"5.10"} = $feature_bundle{sprintf("%vd",$^V)};
18
19	1	1.0e-6	1.0e-6	$feature_bundle{"5.9.5"} = $feature_bundle{"5.10.0"};
20
21				# TODO:
22				# - think about versioned features (use feature switch => 2)
23
24				=head1 NAME
25
26				feature - Perl pragma to enable new syntactic features
27
28				=head1 SYNOPSIS
29
30				use feature qw(switch say);
31				given ($foo) {
32				when (1) { say "\$foo == 1" }
33				when ([2,3]) { say "\$foo == 2 \|\| \$foo == 3" }
34				when (/^a[bc]d$/) { say "\$foo eq 'abd' \|\| \$foo eq 'acd'" }
35				when ($_ > 100) { say "\$foo > 100" }
36				default { say "None of the above" }
37				}
38
39				use feature ':5.10'; # loads all features available in perl 5.10
40
41				=head1 DESCRIPTION
42
43				It is usually impossible to add new syntax to Perl without breaking
44				some existing programs. This pragma provides a way to minimize that
45				risk. New syntactic constructs can be enabled by C<use feature 'foo'>,
46				and will be parsed only when the appropriate feature pragma is in
47				scope.
48
49				=head2 Lexical effect
50
51				Like other pragmas (C<use strict>, for example), features have a lexical
52				effect. C<use feature qw(foo)> will only make the feature "foo" available
53				from that point to the end of the enclosing block.
54
55				{
56				use feature 'say';
57				say "say is available here";
58				}
59				print "But not here.\n";
60
61				=head2 C<no feature>
62
63				Features can also be turned off by using C<no feature "foo">. This too
64				has lexical effect.
65
66				use feature 'say';
67				say "say is available here";
68				{
69				no feature 'say';
70				print "But not here.\n";
71				}
72				say "Yet it is here.";
73
74				C<no feature> with no features specified will turn off all features.
75
76				=head2 The 'switch' feature
77
78				C<use feature 'switch'> tells the compiler to enable the Perl 6
79				given/when construct.
80
81				See L<perlsyn/"Switch statements"> for details.
82
83				=head2 The 'say' feature
84
85				C<use feature 'say'> tells the compiler to enable the Perl 6
86				C<say> function.
87
88				See L<perlfunc/say> for details.
89
90				=head2 the 'state' feature
91
92				C<use feature 'state'> tells the compiler to enable C<state>
93				variables.
94
95				See L<perlsub/"Persistent Private Variables"> for details.
96
97				=head1 FEATURE BUNDLES
98
99				It's possible to load a whole slew of features in one go, using
100				a I<feature bundle>. The name of a feature bundle is prefixed with
101				a colon, to distinguish it from an actual feature. At present, the
102				only feature bundles are C<use feature ":5.10"> and C<use feature ":5.10.0">,
103				which both are equivalent to C<use feature qw(switch say state)>.
104
105				In the forthcoming 5.10.X perl releases, C<use feature ":5.10"> will be
106				equivalent to the latest C<use feature ":5.10.X">.
107
108				=head1 IMPLICIT LOADING
109
110				There are two ways to load the C<feature> pragma implicitly :
111
112				=over 4
113
114				=item *
115
116				By using the C<-E> switch on the command-line instead of C<-e>. It enables
117				all available features in the main compilation unit (that is, the one-liner.)
118
119				=item *
120
121				By requiring explicitly a minimal Perl version number for your program, with
122				the C<use VERSION> construct, and when the version is higher than or equal to
123				5.10.0. That is,
124
125				use 5.10.0;
126
127				will do an implicit
128
129				use feature ':5.10.0';
130
131				and so on.
132
133				But to avoid portability warnings (see L<perlfunc/use>), you may prefer:
134
135				use 5.010;
136
137				with the same effect.
138
139				=back
140
141				=cut
142
143				# spent 185µs within feature::import which was called 4 times, avg 46µs/call: # once (59µs+0) at line 6 of /wise/base/deliv/dev/lib/perl/WISE/UtilsLight.pm # once (47µs+0) at line 7 of /wise/base/deliv/dev/lib/perl/WISE/IPACTbl.pm # once (40µs+0) at line 4 of /wise/base/deliv/dev/lib/perl/WISE/FITSIO/Utils.pm # once (39µs+0) at line 6 of /wise/base/deliv/dev/bin/getfix sub import {
144	12	2.7e-5	2.3e-6	my $class = shift;
145				if (@_ == 0) {
146				croak("No features specified");
147				}
148				while (@_) {
149	56	9.9e-5	1.8e-6	my $name = shift(@_);
150	16	3.0e-5	1.9e-6	if (substr($name, 0, 1) eq ":") {
151				my $v = substr($name, 1);
152				if (!exists $feature_bundle{$v}) {
153				unknown_feature_bundle($v);
154				}
155				unshift @_, @{$feature_bundle{$v}};
156				next;
157				}
158				if (!exists $feature{$name}) {
159				unknown_feature($name);
160				}
161				$^H{$feature{$name}} = 1;
162				}
163				}
164
165				sub unimport {
166				my $class = shift;
167
168				# A bare C<no feature> should disable all features
169				if (!@_) {
170				delete @^H{ values(%feature) };
171				return;
172				}
173
174				while (@_) {
175				my $name = shift;
176				if (substr($name, 0, 1) eq ":") {
177				my $v = substr($name, 1);
178				if (!exists $feature_bundle{$v}) {
179				unknown_feature_bundle($v);
180				}
181				unshift @_, @{$feature_bundle{$v}};
182				next;
183				}
184				if (!exists($feature{$name})) {
185				unknown_feature($name);
186				}
187				else {
188				delete $^H{$feature{$name}};
189				}
190				}
191				}
192
193				sub unknown_feature {
194				my $feature = shift;
195				croak(sprintf('Feature "%s" is not supported by Perl %vd',
196				$feature, $^V));
197				}
198
199				sub unknown_feature_bundle {
200				my $feature = shift;
201				croak(sprintf('Feature bundle "%s" is not supported by Perl %vd',
202				$feature, $^V));
203				}
204
205				sub croak {
206				require Carp;
207				Carp::croak(@_);
208				}
209
210	1	1.4e-5	1.4e-5	1;