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 shift; # without prototype, this argument wouldn't have been passed
105 =head2 C<wrap $name, %opts>
107 Generates a wrapper that calls the function C<$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>.
110 my $push = wrap 'CORE::push';
111 $push->($a, 3, 4); # returns 3 + 2 = 5 and $a now contains 0 .. 4
113 You can force the use of a specific prototype. In this case, C<$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.
115 my $push = wrap { 'CORE::push' => '\@$' }; # only pushes 1 arg
117 Others arguments are seen as key / value pairs that are meant to tune the code generated by L</wrap>. Valid keys are :
121 =item C<< ref => $func >>
123 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>.
125 =item C<< wrong_ref => $code >>
127 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.
129 =item C<< sub => $bool >>
131 Encloses the code into a C<sub { }> block. Default is true.
133 =item C<< compile => $bool >>
135 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.
139 For example, this allows you to recall into C<CORE::grep> and C<CORE::map> by using the C<\&@> prototype :
141 my $grep = wrap { 'CORE::grep' => '\&@' };
142 sub mygrep (&@) { $grep->(@_) } # the prototypes are intentionally different
147 my ($name, $proto, $i, $args, $cr, $opts) = @_;
148 while ($proto =~ s/(\\?)(\[[^\]]+\]|[^\];])//) {
149 my ($ref, $p) = ($1, $2);
150 $p = $1 if $p =~ /^\[([^\]]+)\]/;
151 my $cur = '$_[' . $i . ']';
154 return 'my $r = ' . $opts->{ref} . '(' . $cur . '); '
157 "if (\$r eq '" . $reftypes{$_} ."') { "
158 . _wrap($name, $proto, ($i + 1),
159 $args . $_ . '{' . $cur . '}, ',
163 'e { ' . $opts->{wrong_ref} . ' }'
165 $args .= $p . '{' . $cur . '}, ';
167 } elsif ($p =~ /[\@\%]/) {
168 $args .= '@_[' . $i . '..$#_]';
169 } elsif ($p =~ /\&/) {
170 my %h = do { my $c; map { $_ => $c++ } @$cr };
172 if (not exists $h{$i}) {
178 $args .= 'sub{&{$c[' . $j . ']}}, ';
179 } elsif ($p eq '_') {
180 $args .= '((@_ > ' . $i . ') ? ' . $cur . ' : $_), ';
182 $args .= $cur . ', ';
187 return $name . '(' . $args . ')';
192 croak 'No subroutine specified' unless $name;
196 $proto = prototype $name;
197 } elsif ($r eq 'HASH') {
198 croak 'Forced prototype hash reference must contain exactly one key/value pair' unless keys %$name == 1;
199 ($name, $proto) = %$name;
201 croak 'Unhandled ' . $r . ' reference as first argument';
204 $name =~ s/[\s\$\@\%\*\&;].*//;
205 return $name, $proto;
209 my ($name, $proto) = _check_name shift;
210 croak 'Optional arguments must be passed as key => value pairs' if @_ % 2;
212 $opts{ref} ||= 'ref';
213 $opts{sub} = 1 if not defined $opts{sub};
214 $opts{compile} = 1 if not defined $opts{compile} and $opts{sub};
215 $opts{wrong_ref} = 'undef' if not defined $opts{wrong_ref};
218 if (defined $proto) {
219 $call = _wrap $name, $proto, 0, '', \@cr, \%opts;
221 $call = _wrap $name, '', 0, '@_';
225 . join('', map { 'push @c, $_[' . $_ . ']; ' } @cr)
228 $call = '{ ' . $call . ' }';
229 $call = 'sub ' . $call if $opts{sub};
230 if ($opts{compile}) {
232 croak _clean_msg $@ if $@;
237 =head2 C<recall $name, @args>
239 Calls the function C<$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 => $proto } >> as the first argument.
242 recall { 'CORE::push' => '\@$' }, $a, 1, 2, 3; # $a just contains 1
244 It's implemented in terms of L</wrap>, and hence calls C<eval> at each run.
245 If you plan to recall several times, consider using L</wrap> instead.
250 my $wrap = eval { wrap shift };
251 croak _clean_msg $@ if $@;
257 The functions L</flatten>, L</wrap> and L</recall> are only exported on request, either by providing their name or by the C<':funcs'> and C<':all'> tags.
261 use base qw/Exporter/;
263 use vars qw/@EXPORT @EXPORT_OK %EXPORT_TAGS/;
267 'funcs' => [ qw/flatten wrap recall/ ]
269 @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
270 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
274 L<Carp>, L<Exporter> (core modules since perl 5), L<Scalar::Util> (since 5.7.3).
278 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
280 You can contact me by mail or on C<irc.perl.org> (vincent).
284 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.
288 You can find documentation for this module with the perldoc command.
290 perldoc Sub::Prototype::Util
292 Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Sub-Prototype-Util>.
294 =head1 COPYRIGHT & LICENSE
296 Copyright 2008 Vincent Pit, all rights reserved.
298 This program is free software; you can redistribute it and/or modify it
299 under the same terms as Perl itself.
303 1; # End of Sub::Prototype::Util