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;
52 my ($arg, $sigil) = @_;
55 if (not defined $arg or not defined($reftype = reftype $arg)) {
56 # not defined or plain scalar
57 my $that = (defined $arg) ? 'a plain scalar' : 'undef';
58 croak "Got $that where a reference was expected";
61 croak "Unexpected $reftype reference" unless exists $sigils{$reftype}
62 and $sigil =~ /\Q$sigils{$reftype}\E/;
70 $msg =~ s/(?:\s+called)?\s+at\s+.*$//s;
75 =head2 C<flatten $proto, @args>
77 Flattens the array C<@args> according to the prototype C<$proto>.
78 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.
79 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.
86 return @_ unless defined $proto;
89 while ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])/g) {
94 my $reftype = _check_ref $arg, $sigil;
96 push @args, $reftype eq 'SCALAR'
98 : ($reftype eq 'ARRAY'
100 : ($reftype eq 'HASH'
102 : ($reftype eq 'GLOB'
104 : &$arg # _check_ref ensures this must be a code ref
109 } elsif ($sigil =~ /[\@\%]/) {
113 croak 'Not enough arguments to match this prototype' unless @_;
121 =head2 C<wrap $name, %opts>
123 Generates a wrapper that calls the function C<$name> with a prototyped argument list.
124 That is, the wrapper's arguments should be what C<@_> is when you define a subroutine with the same prototype as C<$name>.
127 my $push = wrap 'CORE::push';
128 $push->($a, 3, 4); # returns 3 + 2 = 5 and $a now contains 0 .. 4
130 You can force the use of a specific prototype.
131 In this case, C<$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.
133 my $push = wrap { 'CORE::push' => '\@$' }; # only pushes 1 arg
135 Others arguments are seen as key / value pairs that are meant to tune the code generated by L</wrap>.
140 =item C<< ref => $func >>
142 Specifies the function used in the generated code to test the reference type of scalars.
143 Defaults to C<'ref'>.
144 You may also want to use L<Scalar::Util/reftype>.
146 =item C<< wrong_ref => $code >>
148 The code executed when a reference of incorrect type is encountered.
149 The result of this snippet is also the result of the generated code, hence it defaults to C<'undef'>.
150 It's a good place to C<croak> or C<die> too.
152 =item C<< sub => $bool >>
154 Encloses the code into a C<sub { }> block.
157 =item C<< compile => $bool >>
159 Makes L</wrap> compile the code generated and return the resulting code reference.
160 Be careful that in this case C<ref> must be a fully qualified function name.
161 Defaults to true, but turned off when C<sub> is false.
165 For example, this allows you to recall into C<CORE::grep> and C<CORE::map> by using the C<\&@> prototype :
167 my $grep = wrap { 'CORE::grep' => '\&@' };
168 sub mygrep (&@) { $grep->(@_) } # the prototypes are intentionally different
173 my ($name, $proto, $i, $args, $coderefs, $opts) = @_;
175 while ($proto =~ s/(\\?)(\[[^\]]+\]|[^\];])//) {
176 my ($ref, $sigil) = ($1, $2);
177 $sigil = $1 if $sigil =~ /^\[([^\]]+)\]/;
182 if (length $sigil > 1) {
183 my $code = "my \$r = $opts->{ref}($cur); ";
186 $name, $proto, ($i + 1), $args . "$_\{$cur}, ", $coderefs, $opts
188 "if (\$r eq '$reftypes{$_}') { $subcall }";
190 $code .= join ' els', @branches, "e { $opts->{wrong_ref} }";
193 $args .= "$sigil\{$cur}, ";
195 } elsif ($sigil =~ /[\@\%]/) {
196 $args .= '@_[' . $i . '..$#_]';
197 } elsif ($sigil =~ /\&/) {
198 my %h = do { my $c; map { $_ => $c++ } @$coderefs };
206 $args .= "sub{&{\$c[$j]}}, ";
207 } elsif ($sigil eq '_') {
208 $args .= "((\@_ > $i) ? $cur : \$_), ";
218 return "$name($args)";
223 croak 'No subroutine specified' unless $name;
228 $proto = prototype $name;
229 } elsif ($r eq 'HASH') {
230 croak 'Forced prototype hash reference must contain exactly one key/value pair' unless keys %$name == 1;
231 ($name, $proto) = %$name;
233 croak 'Unhandled ' . $r . ' reference as first argument';
237 $name =~ s/[\s\$\@\%\*\&;].*//;
239 return $name, $proto;
243 my ($name, $proto) = _check_name shift;
244 croak 'Optional arguments must be passed as key => value pairs' if @_ % 2;
247 $opts{ref} ||= 'ref';
248 $opts{sub} = 1 unless defined $opts{sub};
249 $opts{compile} = 1 if not defined $opts{compile} and $opts{sub};
250 $opts{wrong_ref} = 'undef' unless defined $opts{wrong_ref};
254 if (defined $proto) {
255 $call = _wrap $name, $proto, 0, '', \@coderefs, \%opts;
257 $call = _wrap $name, '', 0, '@_';
261 my $decls = @coderefs > 1 ? 'my @c = @_[' . join(', ', @coderefs) . ']; '
262 : 'my @c = ($_[' . $coderefs[0] . ']); ';
263 $call = $decls . $call;
267 $call = "sub $call" if $opts{sub};
269 if ($opts{compile}) {
276 croak _clean_msg $err if $err;
282 =head2 C<recall $name, @args>
284 Calls the function C<$name> with the prototyped argument list C<@args>.
285 That is, C<@args> should be what C<@_> is when you call a subroutine with C<$name> as prototype.
286 You can still force the prototype by passing C<< { $name => $proto } >> as the first argument.
289 recall { 'CORE::push' => '\@$' }, $a, 1, 2, 3; # $a just contains 1
291 It's implemented in terms of L</wrap>, and hence calls C<eval> at each run.
292 If you plan to recall several times, consider using L</wrap> instead.
299 my $safe_wrap = sub {
305 $wrap = eval { wrap $name };
313 # goto tends to crash a lot on perl 5.8.0
315 my ($wrap, $err) = $safe_wrap->(shift);
316 croak _clean_msg $err if $err;
321 my ($wrap, $err) = $safe_wrap->(shift);
322 croak _clean_msg $err if $err;
330 The functions L</flatten>, L</wrap> and L</recall> are only exported on request, either by providing their name or by the C<':funcs'> and C<':all'> tags.
334 use base qw<Exporter>;
336 use vars qw<@EXPORT @EXPORT_OK %EXPORT_TAGS>;
340 'funcs' => [ qw<flatten wrap recall> ]
342 @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
343 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
347 L<Carp>, L<Exporter> (core modules since perl 5), L<Scalar::Util> (since 5.7.3).
351 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
353 You can contact me by mail or on C<irc.perl.org> (vincent).
357 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>.
358 I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
362 You can find documentation for this module with the perldoc command.
364 perldoc Sub::Prototype::Util
366 Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Sub-Prototype-Util>.
368 =head1 COPYRIGHT & LICENSE
370 Copyright 2008,2009,2010,2011 Vincent Pit, all rights reserved.
372 This program is free software; you can redistribute it and/or modify it
373 under the same terms as Perl itself.
377 1; # End of Sub::Prototype::Util