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.
38 This module provides several utilities aimed at facilitating "overloading" of prototyped functions.
40 They all handle C<5.10>'s C<_> prototype.
46 my %sigils = qw/SCALAR $ ARRAY @ HASH % GLOB * CODE &/;
47 my %reftypes = reverse %sigils;
52 if (!defined $a || !defined($r = reftype $a)) { # not defined or plain scalar
53 croak 'Got ' . ((defined $a) ? 'a plain scalar' : 'undef')
54 . ' where a reference was expected';
56 croak 'Unexpected ' . $r . ' reference' unless exists $sigils{$r}
57 and $p =~ /\Q$sigils{$r}\E/;
63 $msg =~ s/(?:\s+called)?\s+at\s+.*$//s;
67 =head2 C<flatten $proto, @args>
69 Flattens the array C<@args> according to the prototype C<$proto>.
70 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.
76 return @_ unless defined $proto;
78 while ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])/g) {
82 my $r = _check_ref $a, $p;
83 push @args, $r eq 'SCALAR'
91 : &$a # _check_ref ensures this must be a code ref
95 } elsif ($p =~ /[\@\%]/) {
99 croak 'Not enough arguments to match this prototype' unless @_;
106 =head2 C<wrap $name, %opts>
108 Generates a wrapper that calls the function C<$name> with a prototyped argument list.
109 That is, the wrapper's arguments should be what C<@_> is when you define a subroutine with the same prototype as C<$name>.
112 my $push = wrap 'CORE::push';
113 $push->($a, 3, 4); # returns 3 + 2 = 5 and $a now contains 0 .. 4
115 You can force the use of a specific prototype.
116 In this case, C<$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.
118 my $push = wrap { 'CORE::push' => '\@$' }; # only pushes 1 arg
120 Others arguments are seen as key / value pairs that are meant to tune the code generated by L</wrap>.
125 =item C<< ref => $func >>
127 Specifies the function used in the generated code to test the reference type of scalars.
128 Defaults to C<'ref'>.
129 You may also want to use C<Scalar::Util::reftype>.
131 =item C<< wrong_ref => $code >>
133 The code executed when a reference of incorrect type is encountered.
134 The result of this snippet is also the result of the generated code, hence it defaults to C<'undef'>.
135 It's a good place to C<croak> or C<die> too.
137 =item C<< sub => $bool >>
139 Encloses the code into a C<sub { }> block.
142 =item C<< compile => $bool >>
144 Makes L</wrap> compile the code generated and return the resulting code reference.
145 Be careful that in this case C<ref> must be a fully qualified function name.
146 Defaults to true, but turned off when C<sub> is false.
150 For example, this allows you to recall into C<CORE::grep> and C<CORE::map> by using the C<\&@> prototype :
152 my $grep = wrap { 'CORE::grep' => '\&@' };
153 sub mygrep (&@) { $grep->(@_) } # the prototypes are intentionally different
158 my ($name, $proto, $i, $args, $cr, $opts) = @_;
159 while ($proto =~ s/(\\?)(\[[^\]]+\]|[^\];])//) {
160 my ($ref, $p) = ($1, $2);
161 $p = $1 if $p =~ /^\[([^\]]+)\]/;
162 my $cur = '$_[' . $i . ']';
165 return 'my $r = ' . $opts->{ref} . '(' . $cur . '); '
168 "if (\$r eq '" . $reftypes{$_} ."') { "
169 . _wrap($name, $proto, ($i + 1),
170 $args . $_ . '{' . $cur . '}, ',
174 'e { ' . $opts->{wrong_ref} . ' }'
176 $args .= $p . '{' . $cur . '}, ';
178 } elsif ($p =~ /[\@\%]/) {
179 $args .= '@_[' . $i . '..$#_]';
180 } elsif ($p =~ /\&/) {
181 my %h = do { my $c; map { $_ => $c++ } @$cr };
183 if (not exists $h{$i}) {
189 $args .= 'sub{&{$c[' . $j . ']}}, ';
190 } elsif ($p eq '_') {
191 $args .= '((@_ > ' . $i . ') ? ' . $cur . ' : $_), ';
193 $args .= $cur . ', ';
198 return $name . '(' . $args . ')';
203 croak 'No subroutine specified' unless $name;
207 $proto = prototype $name;
208 } elsif ($r eq 'HASH') {
209 croak 'Forced prototype hash reference must contain exactly one key/value pair' unless keys %$name == 1;
210 ($name, $proto) = %$name;
212 croak 'Unhandled ' . $r . ' reference as first argument';
215 $name =~ s/[\s\$\@\%\*\&;].*//;
216 return $name, $proto;
220 my ($name, $proto) = _check_name shift;
221 croak 'Optional arguments must be passed as key => value pairs' if @_ % 2;
223 $opts{ref} ||= 'ref';
224 $opts{sub} = 1 if not defined $opts{sub};
225 $opts{compile} = 1 if not defined $opts{compile} and $opts{sub};
226 $opts{wrong_ref} = 'undef' if not defined $opts{wrong_ref};
229 if (defined $proto) {
230 $call = _wrap $name, $proto, 0, '', \@cr, \%opts;
232 $call = _wrap $name, '', 0, '@_';
236 . join('', map { 'push @c, $_[' . $_ . ']; ' } @cr)
239 $call = '{ ' . $call . ' }';
240 $call = 'sub ' . $call if $opts{sub};
241 if ($opts{compile}) {
243 croak _clean_msg $@ if $@;
248 =head2 C<recall $name, @args>
250 Calls the function C<$name> with the prototyped argument list C<@args>.
251 That is, C<@args> should be what C<@_> is when you call a subroutine with C<$name> as prototype.
252 You can still force the prototype by passing C<< { $name => $proto } >> as the first argument.
255 recall { 'CORE::push' => '\@$' }, $a, 1, 2, 3; # $a just contains 1
257 It's implemented in terms of L</wrap>, and hence calls C<eval> at each run.
258 If you plan to recall several times, consider using L</wrap> instead.
263 my $wrap = eval { wrap shift };
264 croak _clean_msg $@ if $@;
270 The functions L</flatten>, L</wrap> and L</recall> are only exported on request, either by providing their name or by the C<':funcs'> and C<':all'> tags.
274 use base qw/Exporter/;
276 use vars qw/@EXPORT @EXPORT_OK %EXPORT_TAGS/;
280 'funcs' => [ qw/flatten wrap recall/ ]
282 @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
283 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
287 L<Carp>, L<Exporter> (core modules since perl 5), L<Scalar::Util> (since 5.7.3).
291 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
293 You can contact me by mail or on C<irc.perl.org> (vincent).
297 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>.
298 I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
302 You can find documentation for this module with the perldoc command.
304 perldoc Sub::Prototype::Util
306 Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Sub-Prototype-Util>.
308 =head1 COPYRIGHT & LICENSE
310 Copyright 2008 Vincent Pit, all rights reserved.
312 This program is free software; you can redistribute it and/or modify it
313 under the same terms as Perl itself.
317 1; # End of Sub::Prototype::Util