1 package Sub::Prototype::Util;
9 use Scalar::Util qw/reftype/;
13 Sub::Prototype::Util - Prototype-related utility routines.
21 use vars qw/$VERSION/;
27 use Sub::Prototype::Util qw/flatten wrap recall/;
30 my @args = ( \@a, 1, { d => 2 }, undef, 3 );
32 my @flat = flatten '\@$;$', @args; # ('a', 'b', 'c', 1, { d => 2 })
33 recall 'CORE::push', @args; # @a contains 'a', 'b', 'c', 1, { d => 2 }, undef, 3
34 my $splice = wrap 'CORE::splice';
35 my @b = $splice->(\@a, 4, 2); # @a is now ('a', 'b', 'c', 1, 3) and @b is ({ d => 2 }, undef)
39 Prototypes are evil, but sometimes you just have to bear with them, especially when messing with core functions.
40 This module provides several utilities aimed at facilitating "overloading" of prototyped functions.
42 They all handle C<5.10>'s C<_> prototype.
48 my %sigils = qw/SCALAR $ ARRAY @ HASH % GLOB * CODE &/;
49 my %reftypes = reverse %sigils;
54 if (!defined $a || !defined($r = reftype $a)) { # not defined or plain scalar
55 croak 'Got ' . ((defined $a) ? 'a plain scalar' : 'undef')
56 . ' where a reference was expected';
58 croak 'Unexpected ' . $r . ' reference' unless exists $sigils{$r}
59 and $p =~ /\Q$sigils{$r}\E/;
65 $msg =~ s/(?:\s+called)?\s+at\s+.*$//s;
69 =head2 C<flatten $proto, @args>
71 Flattens the array C<@args> according to the prototype C<$proto>.
72 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.
78 return @_ unless defined $proto;
80 while ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])/g) {
84 my $r = _check_ref $a, $p;
85 push @args, $r eq 'SCALAR'
93 : &$a # _check_ref ensures this must be a code ref
97 } elsif ($p =~ /[\@\%]/) {
101 croak 'Not enough arguments to match this prototype' unless @_;
108 =head2 C<wrap $name, %opts>
110 Generates a wrapper that calls the function C<$name> with a prototyped argument list.
111 That is, the wrapper's arguments should be what C<@_> is when you define a subroutine with the same prototype as C<$name>.
114 my $push = wrap 'CORE::push';
115 $push->($a, 3, 4); # returns 3 + 2 = 5 and $a now contains 0 .. 4
117 You can force the use of a specific prototype.
118 In this case, C<$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.
120 my $push = wrap { 'CORE::push' => '\@$' }; # only pushes 1 arg
122 Others arguments are seen as key / value pairs that are meant to tune the code generated by L</wrap>.
127 =item C<< ref => $func >>
129 Specifies the function used in the generated code to test the reference type of scalars.
130 Defaults to C<'ref'>.
131 You may also want to use C<Scalar::Util::reftype>.
133 =item C<< wrong_ref => $code >>
135 The code executed when a reference of incorrect type is encountered.
136 The result of this snippet is also the result of the generated code, hence it defaults to C<'undef'>.
137 It's a good place to C<croak> or C<die> too.
139 =item C<< sub => $bool >>
141 Encloses the code into a C<sub { }> block.
144 =item C<< compile => $bool >>
146 Makes L</wrap> compile the code generated and return the resulting code reference.
147 Be careful that in this case C<ref> must be a fully qualified function name.
148 Defaults to true, but turned off when C<sub> is false.
152 For example, this allows you to recall into C<CORE::grep> and C<CORE::map> by using the C<\&@> prototype :
154 my $grep = wrap { 'CORE::grep' => '\&@' };
155 sub mygrep (&@) { $grep->(@_) } # the prototypes are intentionally different
160 my ($name, $proto, $i, $args, $cr, $opts) = @_;
161 while ($proto =~ s/(\\?)(\[[^\]]+\]|[^\];])//) {
162 my ($ref, $p) = ($1, $2);
163 $p = $1 if $p =~ /^\[([^\]]+)\]/;
164 my $cur = '$_[' . $i . ']';
167 return 'my $r = ' . $opts->{ref} . '(' . $cur . '); '
170 "if (\$r eq '" . $reftypes{$_} ."') { "
171 . _wrap($name, $proto, ($i + 1),
172 $args . $_ . '{' . $cur . '}, ',
176 'e { ' . $opts->{wrong_ref} . ' }'
178 $args .= $p . '{' . $cur . '}, ';
180 } elsif ($p =~ /[\@\%]/) {
181 $args .= '@_[' . $i . '..$#_]';
182 } elsif ($p =~ /\&/) {
183 my %h = do { my $c; map { $_ => $c++ } @$cr };
185 if (not exists $h{$i}) {
191 $args .= 'sub{&{$c[' . $j . ']}}, ';
192 } elsif ($p eq '_') {
193 $args .= '((@_ > ' . $i . ') ? ' . $cur . ' : $_), ';
195 $args .= $cur . ', ';
200 return $name . '(' . $args . ')';
205 croak 'No subroutine specified' unless $name;
209 $proto = prototype $name;
210 } elsif ($r eq 'HASH') {
211 croak 'Forced prototype hash reference must contain exactly one key/value pair' unless keys %$name == 1;
212 ($name, $proto) = %$name;
214 croak 'Unhandled ' . $r . ' reference as first argument';
217 $name =~ s/[\s\$\@\%\*\&;].*//;
218 return $name, $proto;
222 my ($name, $proto) = _check_name shift;
223 croak 'Optional arguments must be passed as key => value pairs' if @_ % 2;
225 $opts{ref} ||= 'ref';
226 $opts{sub} = 1 if not defined $opts{sub};
227 $opts{compile} = 1 if not defined $opts{compile} and $opts{sub};
228 $opts{wrong_ref} = 'undef' if not defined $opts{wrong_ref};
231 if (defined $proto) {
232 $call = _wrap $name, $proto, 0, '', \@cr, \%opts;
234 $call = _wrap $name, '', 0, '@_';
238 . join('', map { 'push @c, $_[' . $_ . ']; ' } @cr)
241 $call = '{ ' . $call . ' }';
242 $call = 'sub ' . $call if $opts{sub};
243 if ($opts{compile}) {
245 croak _clean_msg $@ if $@;
250 =head2 C<recall $name, @args>
252 Calls the function C<$name> with the prototyped argument list C<@args>.
253 That is, C<@args> should be what C<@_> is when you call a subroutine with C<$name> as prototype.
254 You can still force the prototype by passing C<< { $name => $proto } >> as the first argument.
257 recall { 'CORE::push' => '\@$' }, $a, 1, 2, 3; # $a just contains 1
259 It's implemented in terms of L</wrap>, and hence calls C<eval> at each run.
260 If you plan to recall several times, consider using L</wrap> instead.
265 my $wrap = eval { wrap shift };
266 croak _clean_msg $@ if $@;
272 The functions L</flatten>, L</wrap> and L</recall> are only exported on request, either by providing their name or by the C<':funcs'> and C<':all'> tags.
276 use base qw/Exporter/;
278 use vars qw/@EXPORT @EXPORT_OK %EXPORT_TAGS/;
282 'funcs' => [ qw/flatten wrap recall/ ]
284 @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
285 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
289 L<Carp>, L<Exporter> (core modules since perl 5), L<Scalar::Util> (since 5.7.3).
293 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
295 You can contact me by mail or on C<irc.perl.org> (vincent).
299 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>.
300 I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
304 You can find documentation for this module with the perldoc command.
306 perldoc Sub::Prototype::Util
308 Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Sub-Prototype-Util>.
310 =head1 COPYRIGHT & LICENSE
312 Copyright 2008 Vincent Pit, all rights reserved.
314 This program is free software; you can redistribute it and/or modify it
315 under the same terms as Perl itself.
319 1; # End of Sub::Prototype::Util