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Upgrade to Scalar-List-Utils 1.45 from CPAN
[perl5.git] / cpan / Scalar-List-Utils / lib / Sub / Util.pm
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1# Copyright (c) 2014 Paul Evans <leonerd@leonerd.org.uk>. All rights reserved.
2# This program is free software; you can redistribute it and/or
3# modify it under the same terms as Perl itself.
4
5package Sub::Util;
6
7use strict;
8use warnings;
9
10require Exporter;
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11
12our @ISA = qw( Exporter );
13our @EXPORT_OK = qw(
14 prototype set_prototype
15 subname set_subname
16);
17
e8164ee7 18our $VERSION = "1.45";
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19$VERSION = eval $VERSION;
20
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21require List::Util; # as it has the XS
22List::Util->VERSION( $VERSION ); # Ensure we got the right XS version (RT#100863)
23
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24=head1 NAME
25
26Sub::Util - A selection of utility subroutines for subs and CODE references
27
28=head1 SYNOPSIS
29
46274848 30 use Sub::Util qw( prototype set_prototype subname set_subname );
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31
32=head1 DESCRIPTION
33
34C<Sub::Util> contains a selection of utility subroutines that are useful for
35operating on subs and CODE references.
36
37The rationale for inclusion in this module is that the function performs some
38work for which an XS implementation is essential because it cannot be
39implemented in Pure Perl, and which is sufficiently-widely used across CPAN
40that its popularity warrants inclusion in a core module, which this is.
41
42=cut
43
44=head1 FUNCTIONS
45
46=cut
47
48=head2 prototype
49
50 my $proto = prototype( $code )
51
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52I<Since version 1.40.>
53
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54Returns the prototype of the given C<$code> reference, if it has one, as a
55string. This is the same as the C<CORE::prototype> operator; it is included
56here simply for symmetry and completeness with the other functions.
57
58=cut
59
60sub prototype
61{
62 my ( $code ) = @_;
63 return CORE::prototype( $code );
64}
65
66=head2 set_prototype
67
68 my $code = set_prototype $prototype, $code;
69
70I<Since version 1.40.>
71
72Sets the prototype of the function given by the C<$code> reference, or deletes
73it if C<$prototype> is C<undef>. Returns the C<$code> reference itself.
74
75I<Caution>: This function takes arguments in a different order to the previous
76copy of the code from C<Scalar::Util>. This is to match the order of
77C<set_subname>, and other potential additions in this file. This order has
78been chosen as it allows a neat and simple chaining of other
79C<Sub::Util::set_*> functions as might become available, such as:
80
81 my $code =
82 set_subname name_here =>
83 set_prototype '&@' =>
84 set_attribute ':lvalue' =>
85 sub { ...... };
86
87=cut
88
89=head2 subname
90
91 my $name = subname( $code )
92
93I<Since version 1.40.>
94
95Returns the name of the given C<$code> reference, if it has one. Normal named
96subs will give a fully-qualified name consisting of the package and the
97localname separated by C<::>. Anonymous code references will give C<__ANON__>
98as the localname. If a name has been set using L</set_subname>, this name will
99be returned instead.
100
101This function was inspired by C<sub_fullname> from L<Sub::Identify>. The
102remaining functions that C<Sub::Identify> implements can easily be emulated
103using regexp operations, such as
104
105 sub get_code_info { return (subname $_[0]) =~ m/^(.+)::(.+?)$/ }
106 sub sub_name { return (get_code_info $_[0])[0] }
107 sub stash_name { return (get_code_info $_[0])[1] }
108
109I<Users of Sub::Name beware>: This function is B<not> the same as
110C<Sub::Name::subname>; it returns the existing name of the sub rather than
111changing it. To set or change a name, see instead L</set_subname>.
112
113=cut
114
115=head2 set_subname
116
117 my $code = set_subname $name, $code;
118
119I<Since version 1.40.>
120
121Sets the name of the function given by the C<$code> reference. Returns the
122C<$code> reference itself. If the C<$name> is unqualified, the package of the
123caller is used to qualify it.
124
125This is useful for applying names to anonymous CODE references so that stack
126traces and similar situations, to give a useful name rather than having the
127default of C<__ANON__>. Note that this name is only used for this situation;
128the C<set_subname> will not install it into the symbol table; you will have to
129do that yourself if required.
130
131However, since the name is not used by perl except as the return value of
132C<caller>, for stack traces or similar, there is no actual requirement that
133the name be syntactically valid as a perl function name. This could be used to
134attach extra information that could be useful in debugging stack traces.
135
136This function was copied from C<Sub::Name::subname> and renamed to the naming
137convention of this module.
138
139=cut
140
141=head1 AUTHOR
142
143The general structure of this module was written by Paul Evans
144<leonerd@leonerd.org.uk>.
145
146The XS implementation of L</set_subname> was copied from L<Sub::Name> by
147Matthijs van Duin <xmath@cpan.org>
148
149=cut
150
1511;