1 package Sub::Prototype::Util;
7 use Scalar::Util qw/reftype/;
11 Sub::Prototype::Util - Prototype-related utility routines.
19 use vars qw/$VERSION/;
25 use Sub::Prototype::Util qw/flatten wrap recall/;
28 my @args = ( \@a, 1, { d => 2 }, undef, 3 );
30 my @flat = flatten '\@$;$', @args; # ('a', 'b', 'c', 1, { d => 2 })
31 recall 'CORE::push', @args; # @a contains 'a', 'b', 'c', 1, { d => 2 }, undef, 3
32 my $splice = wrap 'CORE::splice';
33 my @b = $splice->(\@a, 4, 2); # @a is now ('a', 'b', 'c', 1, 3) and @b is ({ d => 2 }, undef)
37 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.
39 They all handle C<5.10>'s C<_> prototype.
45 my %sigils = qw/SCALAR $ ARRAY @ HASH % GLOB * CODE &/;
46 my %reftypes = reverse %sigils;
51 if (!defined $a || !defined($r = reftype $a)) { # not defined or plain scalar
52 croak 'Got ' . ((defined $a) ? 'a plain scalar' : 'undef')
53 . ' where a reference was expected';
55 croak 'Unexpected ' . $r . ' reference' unless exists $sigils{$r}
56 and $p =~ /\Q$sigils{$r}\E/;
62 $msg =~ s/(?:\s+called)?\s+at\s+.*$//s;
66 =head2 C<flatten $proto, @args>
68 Flattens the array C<@args> according to the prototype C<$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.
74 return @_ unless defined $proto;
76 while ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])/g) {
80 my $r = _check_ref $a, $p;
81 push @args, $r eq 'SCALAR'
89 : &$a # _check_ref ensures this must be a code ref
93 } elsif ($p =~ /[\@\%]/) {
97 croak 'Not enough arguments to match this prototype' unless @_;
104 =head2 C<wrap $name, %opts>
106 Generates a wrapper that calls the function C<$name> with a prototyped argument list. That is, the wrapper's arguments should be what C<@_> is when you define a subroutine with the same prototype as C<$name>.
109 my $push = wrap 'CORE::push';
110 $push->($a, 3, 4); # returns 3 + 2 = 5 and $a now contains 0 .. 4
112 You can force the use of a specific prototype. In this case, C<$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.
114 my $push = wrap { 'CORE::push' => '\@$' }; # only pushes 1 arg
116 Others arguments are seen as key / value pairs that are meant to tune the code generated by L</wrap>. Valid keys are :
120 =item C<< ref => $func >>
122 Specifies the function used in the generated code to test the reference type of scalars. Defaults to C<'ref'>. You may also want to use C<Scalar::Util::reftype>.
124 =item C<< wrong_ref => $code >>
126 The code executed when a reference of incorrect type is encountered. The result of this snippet is also the result of the generated code, hence it defaults to C<'undef'>. It's a good place to C<croak> or C<die> too.
128 =item C<< sub => $bool >>
130 Encloses the code into a C<sub { }> block. Default is true.
132 =item C<< compile => $bool >>
134 Makes L</wrap> compile the code generated and return the resulting code reference. Be careful that in this case C<ref> must be a fully qualified function name. Defaults to true, but turned off when C<sub> is false.
138 For example, this allows you to recall into C<CORE::grep> and C<CORE::map> by using the C<\&@> prototype :
140 my $grep = wrap { 'CORE::grep' => '\&@' };
141 sub mygrep (&@) { $grep->(@_) } # the prototypes are intentionally different
146 my ($name, $proto, $i, $args, $cr, $opts) = @_;
147 while ($proto =~ s/(\\?)(\[[^\]]+\]|[^\];])//) {
148 my ($ref, $p) = ($1, $2);
149 $p = $1 if $p =~ /^\[([^\]]+)\]/;
150 my $cur = '$_[' . $i . ']';
153 return 'my $r = ' . $opts->{ref} . '(' . $cur . '); '
156 "if (\$r eq '" . $reftypes{$_} ."') { "
157 . _wrap($name, $proto, ($i + 1),
158 $args . $_ . '{' . $cur . '}, ',
162 'e { ' . $opts->{wrong_ref} . ' }'
164 $args .= $p . '{' . $cur . '}, ';
166 } elsif ($p =~ /[\@\%]/) {
167 $args .= '@_[' . $i . '..$#_]';
168 } elsif ($p =~ /\&/) {
169 my %h = do { my $c; map { $_ => $c++ } @$cr };
171 if (not exists $h{$i}) {
177 $args .= 'sub{&{$c[' . $j . ']}}, ';
178 } elsif ($p eq '_') {
179 $args .= '((@_ > ' . $i . ') ? ' . $cur . ' : $_), ';
181 $args .= $cur . ', ';
186 return $name . '(' . $args . ')';
191 croak 'No subroutine specified' unless $name;
195 $proto = prototype $name;
196 } elsif ($r eq 'HASH') {
197 croak 'Forced prototype hash reference must contain exactly one key/value pair' unless keys %$name == 1;
198 ($name, $proto) = %$name;
200 croak 'Unhandled ' . $r . ' reference as first argument';
203 $name =~ s/[\s\$\@\%\*\&;].*//;
204 return $name, $proto;
208 my ($name, $proto) = _check_name shift;
209 croak 'Optional arguments must be passed as key => value pairs' if @_ % 2;
211 $opts{ref} ||= 'ref';
212 $opts{sub} = 1 if not defined $opts{sub};
213 $opts{compile} = 1 if not defined $opts{compile} and $opts{sub};
214 $opts{wrong_ref} = 'undef' if not defined $opts{wrong_ref};
217 if (defined $proto) {
218 $call = _wrap $name, $proto, 0, '', \@cr, \%opts;
220 $call = _wrap $name, '', 0, '@_';
224 . join('', map { 'push @c, $_[' . $_ . ']; ' } @cr)
227 $call = '{ ' . $call . ' }';
228 $call = 'sub ' . $call if $opts{sub};
229 if ($opts{compile}) {
231 croak _clean_msg $@ if $@;
236 =head2 C<recall $name, @args>
238 Calls the function C<$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>. You can still force the prototype by passing C<< { $name => $proto } >> as the first argument.
241 recall { 'CORE::push' => '\@$' }, $a, 1, 2, 3; # $a just contains 1
243 It's implemented in terms of L</wrap>, and hence calls C<eval> at each run.
244 If you plan to recall several times, consider using L</wrap> instead.
249 my $wrap = eval { wrap shift };
250 croak _clean_msg $@ if $@;
256 The functions L</flatten>, L</wrap> and L</recall> are only exported on request, either by providing their name or by the C<':funcs'> and C<':all'> tags.
260 use base qw/Exporter/;
262 use vars qw/@EXPORT @EXPORT_OK %EXPORT_TAGS/;
266 'funcs' => [ qw/flatten wrap recall/ ]
268 @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
269 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
273 L<Carp>, L<Exporter> (core modules since perl 5), L<Scalar::Util> (since 5.7.3).
277 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
279 You can contact me by mail or on C<irc.perl.org> (vincent).
283 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.
287 You can find documentation for this module with the perldoc command.
289 perldoc Sub::Prototype::Util
291 Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Sub-Prototype-Util>.
293 =head1 COPYRIGHT & LICENSE
295 Copyright 2008 Vincent Pit, all rights reserved.
297 This program is free software; you can redistribute it and/or modify it
298 under the same terms as Perl itself.
302 1; # End of Sub::Prototype::Util