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.
73 It croaks if the arguments can't possibly match the required prototype, e.g. when a reference type is wrong or when not enough elements were provided.
79 return @_ unless defined $proto;
81 while ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])/g) {
85 my $r = _check_ref $a, $p;
86 push @args, $r eq 'SCALAR'
94 : &$a # _check_ref ensures this must be a code ref
98 } elsif ($p =~ /[\@\%]/) {
102 croak 'Not enough arguments to match this prototype' unless @_;
109 =head2 C<wrap $name, %opts>
111 Generates a wrapper that calls the function C<$name> with a prototyped argument list.
112 That is, the wrapper's arguments should be what C<@_> is when you define a subroutine with the same prototype as C<$name>.
115 my $push = wrap 'CORE::push';
116 $push->($a, 3, 4); # returns 3 + 2 = 5 and $a now contains 0 .. 4
118 You can force the use of a specific prototype.
119 In this case, C<$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.
121 my $push = wrap { 'CORE::push' => '\@$' }; # only pushes 1 arg
123 Others arguments are seen as key / value pairs that are meant to tune the code generated by L</wrap>.
128 =item C<< ref => $func >>
130 Specifies the function used in the generated code to test the reference type of scalars.
131 Defaults to C<'ref'>.
132 You may also want to use L<Scalar::Util/reftype>.
134 =item C<< wrong_ref => $code >>
136 The code executed when a reference of incorrect type is encountered.
137 The result of this snippet is also the result of the generated code, hence it defaults to C<'undef'>.
138 It's a good place to C<croak> or C<die> too.
140 =item C<< sub => $bool >>
142 Encloses the code into a C<sub { }> block.
145 =item C<< compile => $bool >>
147 Makes L</wrap> compile the code generated and return the resulting code reference.
148 Be careful that in this case C<ref> must be a fully qualified function name.
149 Defaults to true, but turned off when C<sub> is false.
153 For example, this allows you to recall into C<CORE::grep> and C<CORE::map> by using the C<\&@> prototype :
155 my $grep = wrap { 'CORE::grep' => '\&@' };
156 sub mygrep (&@) { $grep->(@_) } # the prototypes are intentionally different
161 my ($name, $proto, $i, $args, $coderefs, $opts) = @_;
163 while ($proto =~ s/(\\?)(\[[^\]]+\]|[^\];])//) {
164 my ($ref, $sigil) = ($1, $2);
165 $sigil = $1 if $sigil =~ /^\[([^\]]+)\]/;
170 if (length $sigil > 1) {
171 my $code = "my \$r = $opts->{ref}($cur); ";
174 $name, $proto, ($i + 1), $args . "$_\{$cur}, ", $coderefs, $opts
176 "if (\$r eq '$reftypes{$_}') { $subcall }";
178 $code .= join ' els', @branches, "e { $opts->{wrong_ref} }";
181 $args .= "$sigil\{$cur}, ";
183 } elsif ($sigil =~ /[\@\%]/) {
184 $args .= '@_[' . $i . '..$#_]';
185 } elsif ($sigil =~ /\&/) {
186 my %h = do { my $c; map { $_ => $c++ } @$coderefs };
194 $args .= "sub{&{\$c[$j]}}, ";
195 } elsif ($sigil eq '_') {
196 $args .= "((\@_ > $i) ? $cur : \$_), ";
206 return "$name($args)";
211 croak 'No subroutine specified' unless $name;
216 $proto = prototype $name;
217 } elsif ($r eq 'HASH') {
218 croak 'Forced prototype hash reference must contain exactly one key/value pair' unless keys %$name == 1;
219 ($name, $proto) = %$name;
221 croak 'Unhandled ' . $r . ' reference as first argument';
225 $name =~ s/[\s\$\@\%\*\&;].*//;
227 return $name, $proto;
231 my ($name, $proto) = _check_name shift;
232 croak 'Optional arguments must be passed as key => value pairs' if @_ % 2;
235 $opts{ref} ||= 'ref';
236 $opts{sub} = 1 unless defined $opts{sub};
237 $opts{compile} = 1 if not defined $opts{compile} and $opts{sub};
238 $opts{wrong_ref} = 'undef' unless defined $opts{wrong_ref};
242 if (defined $proto) {
243 $call = _wrap $name, $proto, 0, '', \@coderefs, \%opts;
245 $call = _wrap $name, '', 0, '@_';
249 my $decls = @coderefs > 1 ? 'my @c = @_[' . join(', ', @coderefs) . ']; '
250 : 'my @c = ($_[' . $coderefs[0] . ']); ';
251 $call = $decls . $call;
255 $call = "sub $call" if $opts{sub};
257 if ($opts{compile}) {
264 croak _clean_msg $err if $err;
270 =head2 C<recall $name, @args>
272 Calls the function C<$name> with the prototyped argument list C<@args>.
273 That is, C<@args> should be what C<@_> is when you call a subroutine with C<$name> as prototype.
274 You can still force the prototype by passing C<< { $name => $proto } >> as the first argument.
277 recall { 'CORE::push' => '\@$' }, $a, 1, 2, 3; # $a just contains 1
279 It's implemented in terms of L</wrap>, and hence calls C<eval> at each run.
280 If you plan to recall several times, consider using L</wrap> instead.
285 my $wrap = eval { wrap shift };
286 croak _clean_msg $@ if $@;
292 The functions L</flatten>, L</wrap> and L</recall> are only exported on request, either by providing their name or by the C<':funcs'> and C<':all'> tags.
296 use base qw/Exporter/;
298 use vars qw/@EXPORT @EXPORT_OK %EXPORT_TAGS/;
302 'funcs' => [ qw/flatten wrap recall/ ]
304 @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
305 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
309 L<Carp>, L<Exporter> (core modules since perl 5), L<Scalar::Util> (since 5.7.3).
313 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
315 You can contact me by mail or on C<irc.perl.org> (vincent).
319 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>.
320 I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
324 You can find documentation for this module with the perldoc command.
326 perldoc Sub::Prototype::Util
328 Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Sub-Prototype-Util>.
330 =head1 COPYRIGHT & LICENSE
332 Copyright 2008,2009,2010,2011 Vincent Pit, all rights reserved.
334 This program is free software; you can redistribute it and/or modify it
335 under the same terms as Perl itself.
339 1; # End of Sub::Prototype::Util