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;
77 my @flattened = flatten($proto, @args);
79 Flattens the array C<@args> according to the prototype C<$proto>.
80 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.
81 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.
88 return @_ unless defined $proto;
91 while ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])/g) {
96 my $reftype = _check_ref $arg, $sigil;
98 push @args, $reftype eq 'SCALAR'
100 : ($reftype eq 'ARRAY'
102 : ($reftype eq 'HASH'
104 : ($reftype eq 'GLOB'
106 : &$arg # _check_ref ensures this must be a code ref
111 } elsif ($sigil =~ /[\@\%]/) {
115 croak 'Not enough arguments to match this prototype' unless @_;
125 my $wrapper = wrap($name, %opts);
126 my $wrapper = wrap({ $name => $proto }, %opts);
128 Generates a wrapper that calls the function C<$name> with a prototyped argument list.
129 That is, the wrapper's arguments should be what C<@_> is when you define a subroutine with the same prototype as C<$name>.
132 my $push = wrap 'CORE::push';
133 $push->($a, 3, 4); # returns 3 + 2 = 5 and $a now contains 0 .. 4
135 You can force the use of a specific prototype.
136 In this case, C<$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.
138 my $push = wrap { 'CORE::push' => '\@$' }; # only pushes 1 arg
140 The remaining arguments C<%opts> are treated as key / value pairs that are meant to tune the code generated by L</wrap>.
145 =item C<< ref => $func >>
147 Specifies the function used in the generated code to test the reference type of scalars.
148 Defaults to C<'ref'>.
149 You may also want to use L<Scalar::Util/reftype>.
151 =item C<< wrong_ref => $code >>
153 The code executed when a reference of incorrect type is encountered.
154 The result of this snippet is also the result of the generated code, hence it defaults to C<'undef'>.
155 It's a good place to C<croak> or C<die> too.
157 =item C<< sub => $bool >>
159 Encloses the code into a C<sub { }> block.
162 =item C<< compile => $bool >>
164 Makes L</wrap> compile the code generated and return the resulting code reference.
165 Be careful that in this case C<ref> must be a fully qualified function name.
166 Defaults to true, but turned off when C<sub> is false.
170 For example, this allows you to recall into C<CORE::grep> and C<CORE::map> by using the C<\&@> prototype :
172 my $grep = wrap { 'CORE::grep' => '\&@' };
173 sub mygrep (&@) { $grep->(@_) } # the prototypes are intentionally different
178 my ($name, $proto, $i, $args, $coderefs, $opts) = @_;
180 while ($proto =~ s/(\\?)(\[[^\]]+\]|[^\];])//) {
181 my ($ref, $sigil) = ($1, $2);
182 $sigil = $1 if $sigil =~ /^\[([^\]]+)\]/;
187 if (length $sigil > 1) {
188 my $code = "my \$r = $opts->{ref}($cur); ";
191 $name, $proto, ($i + 1), $args . "$_\{$cur}, ", $coderefs, $opts
193 "if (\$r eq '$reftypes{$_}') { $subcall }";
195 $code .= join ' els', @branches, "e { $opts->{wrong_ref} }";
198 $args .= "$sigil\{$cur}, ";
200 } elsif ($sigil =~ /[\@\%]/) {
201 $args .= '@_[' . $i . '..$#_]';
202 } elsif ($sigil =~ /\&/) {
203 my %h = do { my $c; map { $_ => $c++ } @$coderefs };
211 $args .= "sub{&{\$c[$j]}}, ";
212 } elsif ($sigil eq '_') {
213 $args .= "((\@_ > $i) ? $cur : \$_), ";
223 return "$name($args)";
228 croak 'No subroutine specified' unless $name;
233 $proto = prototype $name;
234 } elsif ($r eq 'HASH') {
235 croak 'Forced prototype hash reference must contain exactly one key/value pair' unless keys %$name == 1;
236 ($name, $proto) = %$name;
238 croak 'Unhandled ' . $r . ' reference as first argument';
242 $name =~ s/[\s\$\@\%\*\&;].*//;
244 return $name, $proto;
248 my ($name, $proto) = _check_name shift;
249 croak 'Optional arguments must be passed as key => value pairs' if @_ % 2;
252 $opts{ref} ||= 'ref';
253 $opts{sub} = 1 unless defined $opts{sub};
254 $opts{compile} = 1 if not defined $opts{compile} and $opts{sub};
255 $opts{wrong_ref} = 'undef' unless defined $opts{wrong_ref};
259 if (defined $proto) {
260 $call = _wrap $name, $proto, 0, '', \@coderefs, \%opts;
262 $call = _wrap $name, '', 0, '@_';
266 my $decls = @coderefs > 1 ? 'my @c = @_[' . join(', ', @coderefs) . ']; '
267 : 'my @c = ($_[' . $coderefs[0] . ']); ';
268 $call = $decls . $call;
272 $call = "sub $call" if $opts{sub};
274 if ($opts{compile}) {
281 croak _clean_msg $err if $err;
289 my @res = recall($name, @args);
290 my @res = recall({ $name => $proto }, @args);
292 Calls the function C<$name> with the prototyped argument list C<@args>.
293 That is, C<@args> should be what C<@_> is when you call a subroutine with C<$name> as prototype.
294 You can still force the prototype by passing C<< { $name => $proto } >> as the first argument.
297 recall { 'CORE::push' => '\@$' }, $a, 1, 2, 3; # $a just contains 1
299 It's implemented in terms of L</wrap>, and hence calls C<eval> at each run.
300 If you plan to recall several times, consider using L</wrap> instead.
307 my $safe_wrap = sub {
313 $wrap = eval { wrap $name };
321 # goto tends to crash a lot on perl 5.8.0
323 my ($wrap, $err) = $safe_wrap->(shift);
324 croak _clean_msg $err if $err;
329 my ($wrap, $err) = $safe_wrap->(shift);
330 croak _clean_msg $err if $err;
338 The functions L</flatten>, L</wrap> and L</recall> are only exported on request, either by providing their name or by the C<':funcs'> and C<':all'> tags.
342 use base qw<Exporter>;
344 use vars qw<@EXPORT @EXPORT_OK %EXPORT_TAGS>;
348 'funcs' => [ qw<flatten wrap recall> ]
350 @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
351 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
355 L<Carp>, L<Exporter> (core modules since perl 5), L<Scalar::Util> (since 5.7.3).
359 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
361 You can contact me by mail or on C<irc.perl.org> (vincent).
365 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>.
366 I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
370 You can find documentation for this module with the perldoc command.
372 perldoc Sub::Prototype::Util
374 Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Sub-Prototype-Util>.
376 =head1 COPYRIGHT & LICENSE
378 Copyright 2008,2009,2010,2011 Vincent Pit, all rights reserved.
380 This program is free software; you can redistribute it and/or modify it
381 under the same terms as Perl itself.
385 1; # End of Sub::Prototype::Util