1 package Sub::Prototype::Util;
7 use Scalar::Util qw/reftype/;
11 Sub::Prototype::Util - Prototype-related utility routines.
19 use vars qw/$VERSION/;
25 use Sub::Prototype::Util qw/flatten recall/;
28 my @args = ( \@a, 1, { d => 2 }, undef, 3 );
30 my @flat = flatten '\@$;$', @args; # ('a', 'b', 'c', 1, { d => 2 })
31 recall 'CORE::push', @args; # @a contains 'a', 'b', 'c', 1, { d => 2 }, undef, 3
35 Prototypes are evil, but sometimes you just have to bear with them, especially when messing with core functions. This module provides several utilities aimed at facilitating "overloading" of prototyped functions.
37 They all handle C<5.10>'s C<_> prototype.
43 my %sigils = qw/SCALAR $ ARRAY @ HASH % GLOB * CODE &/;
48 if (!defined $a || !defined($r = reftype $a)) { # not defined or plain scalar
49 croak 'Got ' . ((defined $a) ? 'a plain scalar' : 'undef')
50 . ' where a reference was expected';
52 croak 'Unexpected ' . $r . ' reference' unless exists $sigils{$r}
53 and $p =~ /\Q$sigils{$r}\E/;
57 =head2 C<flatten $proto, @args>
59 Flattens the array C<@args> according to the prototype C<$proto>. When C<@args> is what C<@_> is after calling a subroutine with prototype C<$proto>, C<flatten> returns the list of what C<@_> would have been if there were no prototype.
65 return @_ unless defined $proto;
67 while ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])/g) {
71 my $r = _check_ref $a, $p;
73 SCALAR => sub { push @args, $$a },
74 ARRAY => sub { push @args, @$a },
75 HASH => sub { push @args, %$a },
76 GLOB => sub { push @args, *$a },
77 CODE => sub { push @args, &$a }
80 } elsif ($p =~ /[\@\%]/) {
83 } elsif ($p eq '_' && @_ == 0) {
92 =head2 C<recall $name, @args>
94 Calls the function C<$name> with the prototyped argument list C<@args>. That is, C<@args> should be what C<@_> is when you define a subroutine with the same prototype as C<$name>. For example,
97 recall 'CORE::push', $a, 1, 2, 3;
99 will call C<push @$a, 1, 2, 3> and so fill the arrayref C<$a> with C<1, 2, 3>. This is especially needed for core functions because you can't C<goto> into them.
101 You can also force the use of a specific prototype. In this case, C<$name> must be a hash reference that holds exactly one key/value pair, the key being the function name and the value the prototpye that should be used to call it.
103 recall { 'CORE::push' => '\@$' }, $a, 1, 2, 3; # will only push 1
105 This allows you to recall into C<CORE::grep> and C<CORE::map> by using the C<\&@> prototype :
107 sub mygrep (&@) { recall { 'CORE::grep' => '\&@' }, @_ } # the prototypes are intentionally different
113 croak 'No subroutine specified' unless $name;
117 croak 'Forced prototype hash reference must contain exactly one key/value pair' unless keys %$name == 1;
118 ($name, $proto) = %$name;
119 } elsif (length $r) {
120 croak 'Unhandled ' . $r . ' reference as first argument';
123 $name =~ s/[\s\$\@\%\*\&;].*//;
124 $proto = prototype $name unless $proto;
125 my $call = $name . '(';
127 if (defined $proto) {
129 while ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])/g) {
132 my $r = _check_ref $_[$i], $p;
133 $call .= $sigils{$r} . '{$_[' . $i . ']},';
134 } elsif ($p =~ /[\@\%]/) {
135 $call .= '@_[' . $i . '..' . (@_ - 1) . ']';
137 } elsif ($p =~ /\&/) {
139 $call .= 'sub{&{$cr[' . $#cr . ']}},';
140 } elsif ($p eq '_' && $i >= @_) {
143 $call .= '$_[' . $i . '],';
149 $call .= join ',', map '$_[' . $_ . ']', 0 .. @_ - 1;
152 my @ret = eval $call;
159 The functions L</flatten> and L</recall> are only exported on request, either by providing their name or by the C<':funcs'> and C<':all'> tags.
163 use base qw/Exporter/;
165 use vars qw/@EXPORT @EXPORT_OK %EXPORT_TAGS/;
169 'funcs' => [ qw/flatten recall/ ]
171 @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
172 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
176 L<Carp>, L<Exporter> (core modules since perl 5), L<Scalar::Util> (since 5.7.3).
180 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
182 You can contact me by mail or on #perl @ FreeNode (vincent or Prof_Vince).
186 Please report any bugs or feature requests to C<bug-sub-prototype-util at rt.cpan.org>, or through the web interface at L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Sub-Prototype-Util>. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
190 You can find documentation for this module with the perldoc command.
192 perldoc Sub::Prototype::Util
194 Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Sub-Prototype-Util>.
196 =head1 COPYRIGHT & LICENSE
198 Copyright 2008 Vincent Pit, all rights reserved.
200 This program is free software; you can redistribute it and/or modify it
201 under the same terms as Perl itself.
205 1; # End of Sub::Prototype::Util