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/;
66 $msg =~ s/(?:\s+called)?\s+at\s+.*$//s;
71 =head2 C<flatten $proto, @args>
73 Flattens the array C<@args> according to the prototype C<$proto>.
74 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.
75 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.
82 return @_ unless defined $proto;
85 while ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])/g) {
90 my $reftype = _check_ref $arg, $sigil;
92 push @args, $reftype eq 'SCALAR'
94 : ($reftype eq 'ARRAY'
100 : &$arg # _check_ref ensures this must be a code ref
105 } elsif ($sigil =~ /[\@\%]/) {
109 croak 'Not enough arguments to match this prototype' unless @_;
117 =head2 C<wrap $name, %opts>
119 Generates a wrapper that calls the function C<$name> with a prototyped argument list.
120 That is, the wrapper's arguments should be what C<@_> is when you define a subroutine with the same prototype as C<$name>.
123 my $push = wrap 'CORE::push';
124 $push->($a, 3, 4); # returns 3 + 2 = 5 and $a now contains 0 .. 4
126 You can force the use of a specific prototype.
127 In this case, C<$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.
129 my $push = wrap { 'CORE::push' => '\@$' }; # only pushes 1 arg
131 Others arguments are seen as key / value pairs that are meant to tune the code generated by L</wrap>.
136 =item C<< ref => $func >>
138 Specifies the function used in the generated code to test the reference type of scalars.
139 Defaults to C<'ref'>.
140 You may also want to use L<Scalar::Util/reftype>.
142 =item C<< wrong_ref => $code >>
144 The code executed when a reference of incorrect type is encountered.
145 The result of this snippet is also the result of the generated code, hence it defaults to C<'undef'>.
146 It's a good place to C<croak> or C<die> too.
148 =item C<< sub => $bool >>
150 Encloses the code into a C<sub { }> block.
153 =item C<< compile => $bool >>
155 Makes L</wrap> compile the code generated and return the resulting code reference.
156 Be careful that in this case C<ref> must be a fully qualified function name.
157 Defaults to true, but turned off when C<sub> is false.
161 For example, this allows you to recall into C<CORE::grep> and C<CORE::map> by using the C<\&@> prototype :
163 my $grep = wrap { 'CORE::grep' => '\&@' };
164 sub mygrep (&@) { $grep->(@_) } # the prototypes are intentionally different
169 my ($name, $proto, $i, $args, $coderefs, $opts) = @_;
171 while ($proto =~ s/(\\?)(\[[^\]]+\]|[^\];])//) {
172 my ($ref, $sigil) = ($1, $2);
173 $sigil = $1 if $sigil =~ /^\[([^\]]+)\]/;
178 if (length $sigil > 1) {
179 my $code = "my \$r = $opts->{ref}($cur); ";
182 $name, $proto, ($i + 1), $args . "$_\{$cur}, ", $coderefs, $opts
184 "if (\$r eq '$reftypes{$_}') { $subcall }";
186 $code .= join ' els', @branches, "e { $opts->{wrong_ref} }";
189 $args .= "$sigil\{$cur}, ";
191 } elsif ($sigil =~ /[\@\%]/) {
192 $args .= '@_[' . $i . '..$#_]';
193 } elsif ($sigil =~ /\&/) {
194 my %h = do { my $c; map { $_ => $c++ } @$coderefs };
202 $args .= "sub{&{\$c[$j]}}, ";
203 } elsif ($sigil eq '_') {
204 $args .= "((\@_ > $i) ? $cur : \$_), ";
214 return "$name($args)";
219 croak 'No subroutine specified' unless $name;
224 $proto = prototype $name;
225 } elsif ($r eq 'HASH') {
226 croak 'Forced prototype hash reference must contain exactly one key/value pair' unless keys %$name == 1;
227 ($name, $proto) = %$name;
229 croak 'Unhandled ' . $r . ' reference as first argument';
233 $name =~ s/[\s\$\@\%\*\&;].*//;
235 return $name, $proto;
239 my ($name, $proto) = _check_name shift;
240 croak 'Optional arguments must be passed as key => value pairs' if @_ % 2;
243 $opts{ref} ||= 'ref';
244 $opts{sub} = 1 unless defined $opts{sub};
245 $opts{compile} = 1 if not defined $opts{compile} and $opts{sub};
246 $opts{wrong_ref} = 'undef' unless defined $opts{wrong_ref};
250 if (defined $proto) {
251 $call = _wrap $name, $proto, 0, '', \@coderefs, \%opts;
253 $call = _wrap $name, '', 0, '@_';
257 my $decls = @coderefs > 1 ? 'my @c = @_[' . join(', ', @coderefs) . ']; '
258 : 'my @c = ($_[' . $coderefs[0] . ']); ';
259 $call = $decls . $call;
263 $call = "sub $call" if $opts{sub};
265 if ($opts{compile}) {
272 croak _clean_msg $err if $err;
278 =head2 C<recall $name, @args>
280 Calls the function C<$name> with the prototyped argument list C<@args>.
281 That is, C<@args> should be what C<@_> is when you call a subroutine with C<$name> as prototype.
282 You can still force the prototype by passing C<< { $name => $proto } >> as the first argument.
285 recall { 'CORE::push' => '\@$' }, $a, 1, 2, 3; # $a just contains 1
287 It's implemented in terms of L</wrap>, and hence calls C<eval> at each run.
288 If you plan to recall several times, consider using L</wrap> instead.
298 $wrap = eval { wrap $name };
301 croak _clean_msg $err if $err;
308 The functions L</flatten>, L</wrap> and L</recall> are only exported on request, either by providing their name or by the C<':funcs'> and C<':all'> tags.
312 use base qw/Exporter/;
314 use vars qw/@EXPORT @EXPORT_OK %EXPORT_TAGS/;
318 'funcs' => [ qw/flatten wrap recall/ ]
320 @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
321 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
325 L<Carp>, L<Exporter> (core modules since perl 5), L<Scalar::Util> (since 5.7.3).
329 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
331 You can contact me by mail or on C<irc.perl.org> (vincent).
335 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>.
336 I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
340 You can find documentation for this module with the perldoc command.
342 perldoc Sub::Prototype::Util
344 Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Sub-Prototype-Util>.
346 =head1 COPYRIGHT & LICENSE
348 Copyright 2008,2009,2010,2011 Vincent Pit, all rights reserved.
350 This program is free software; you can redistribute it and/or modify it
351 under the same terms as Perl itself.
355 1; # End of Sub::Prototype::Util