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 C<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, $cr, $opts) = @_;
162 while ($proto =~ s/(\\?)(\[[^\]]+\]|[^\];])//) {
163 my ($ref, $p) = ($1, $2);
164 $p = $1 if $p =~ /^\[([^\]]+)\]/;
165 my $cur = '$_[' . $i . ']';
168 return 'my $r = ' . $opts->{ref} . '(' . $cur . '); '
171 "if (\$r eq '" . $reftypes{$_} ."') { "
172 . _wrap($name, $proto, ($i + 1),
173 $args . $_ . '{' . $cur . '}, ',
177 'e { ' . $opts->{wrong_ref} . ' }'
179 $args .= $p . '{' . $cur . '}, ';
181 } elsif ($p =~ /[\@\%]/) {
182 $args .= '@_[' . $i . '..$#_]';
183 } elsif ($p =~ /\&/) {
184 my %h = do { my $c; map { $_ => $c++ } @$cr };
186 if (not exists $h{$i}) {
192 $args .= 'sub{&{$c[' . $j . ']}}, ';
193 } elsif ($p eq '_') {
194 $args .= '((@_ > ' . $i . ') ? ' . $cur . ' : $_), ';
196 $args .= $cur . ', ';
201 return $name . '(' . $args . ')';
206 croak 'No subroutine specified' unless $name;
210 $proto = prototype $name;
211 } elsif ($r eq 'HASH') {
212 croak 'Forced prototype hash reference must contain exactly one key/value pair' unless keys %$name == 1;
213 ($name, $proto) = %$name;
215 croak 'Unhandled ' . $r . ' reference as first argument';
218 $name =~ s/[\s\$\@\%\*\&;].*//;
219 return $name, $proto;
223 my ($name, $proto) = _check_name shift;
224 croak 'Optional arguments must be passed as key => value pairs' if @_ % 2;
226 $opts{ref} ||= 'ref';
227 $opts{sub} = 1 if not defined $opts{sub};
228 $opts{compile} = 1 if not defined $opts{compile} and $opts{sub};
229 $opts{wrong_ref} = 'undef' if not defined $opts{wrong_ref};
232 if (defined $proto) {
233 $call = _wrap $name, $proto, 0, '', \@cr, \%opts;
235 $call = _wrap $name, '', 0, '@_';
239 . join('', map { 'push @c, $_[' . $_ . ']; ' } @cr)
242 $call = '{ ' . $call . ' }';
243 $call = 'sub ' . $call if $opts{sub};
244 if ($opts{compile}) {
246 croak _clean_msg $@ if $@;
251 =head2 C<recall $name, @args>
253 Calls the function C<$name> with the prototyped argument list C<@args>.
254 That is, C<@args> should be what C<@_> is when you call a subroutine with C<$name> as prototype.
255 You can still force the prototype by passing C<< { $name => $proto } >> as the first argument.
258 recall { 'CORE::push' => '\@$' }, $a, 1, 2, 3; # $a just contains 1
260 It's implemented in terms of L</wrap>, and hence calls C<eval> at each run.
261 If you plan to recall several times, consider using L</wrap> instead.
266 my $wrap = eval { wrap shift };
267 croak _clean_msg $@ if $@;
273 The functions L</flatten>, L</wrap> and L</recall> are only exported on request, either by providing their name or by the C<':funcs'> and C<':all'> tags.
277 use base qw/Exporter/;
279 use vars qw/@EXPORT @EXPORT_OK %EXPORT_TAGS/;
283 'funcs' => [ qw/flatten wrap recall/ ]
285 @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
286 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
290 L<Carp>, L<Exporter> (core modules since perl 5), L<Scalar::Util> (since 5.7.3).
294 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
296 You can contact me by mail or on C<irc.perl.org> (vincent).
300 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>.
301 I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
305 You can find documentation for this module with the perldoc command.
307 perldoc Sub::Prototype::Util
309 Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Sub-Prototype-Util>.
311 =head1 COPYRIGHT & LICENSE
313 Copyright 2008 Vincent Pit, all rights reserved.
315 This program is free software; you can redistribute it and/or modify it
316 under the same terms as Perl itself.
320 1; # End of Sub::Prototype::Util