1 package Lexical::Types;
12 Lexical::Types - Extend the semantics of typed lexicals.
30 sub TYPEDSCALAR { Some::String::Implementation->new }
35 my Str $x; # $x is now a Some::String::Implementation object
39 This module allows you to hook the execution of typed lexicals declarations (C<my Str $x>).
40 In particular, it can be used to automatically tie or bless typed lexicals.
42 It is B<not> implemented with a source filter.
48 XSLoader::load(__PACKAGE__, $VERSION);
53 =head2 C<< import [ as => [ $prefix | $mangler ] ] >>
55 Magically called when writing C<use Lexical::Types>.
56 All the occurences of C<my Str $x> in the current lexical scope will be changed to call at each run a given method in a given package.
57 The method and package are determined by the parameter C<'as'> :
63 If it's left unspecified, the C<TYPEDSCALAR> method in the C<Str> package will be called.
66 my Str $x; # calls Str->TYPEDSCALAR
70 If a plain scalar C<$prefix> is passed as the value, the C<TYPEDSCALAR> method in the C<${prefix}::Str> package will be used.
72 use Lexical::Types as => 'My::'; # or "as => 'My'"
73 my Str $x; # calls My::Str->TYPEDSCALAR
77 If the value given is a code reference C<$mangler>, it will be called at compile-time with arguments C<'Str'> and C<'TYPEDSCALAR'> and is expected to return :
83 either an empty list, in which case the current typed lexical definition will be skipped (thus it won't be altered to trigger a run-time hook) ;
85 use Lexical::Types as => sub { return $_[0] =~ /Str/ ? () : @_ };
86 my Str $x; # nothing special
87 my Int $y; # calls Int->TYPEDSCALAR
91 or the desired package and method name, in that order (if any of those is C<undef>, the default value will be used instead).
93 use Lexical::Types as => sub { 'My', 'new_' . lc($_[0]) };
94 my Str $x; # the coderef indicates to call My->new_str
100 The initializer method receives an alias to the pad entry of C<$x> in C<$_[1]> and the original type name (C<Str>) in C<$_[2]>.
101 You can either edit C<$_[1]> in place, in which case you should return an empty list, or return a new scalar that will be copied into C<$x>.
111 my $as = delete $args{'as'};
117 $as .= '::' if $as !~ /::$/;
118 $hint = _tag(sub { $as . $_[0] });
120 croak "Invalid $r reference for 'as'";
127 # Yes, we store a coderef inside the hints hash, but that's just for compile
129 $^H{+(__PACKAGE__)} = $hint;
134 Magically called when writing C<no Lexical::Types>.
135 Turns the module off.
140 $^H{+(__PACKAGE__)} = undef;
145 You can integrate L<Lexical::Types> in your module so that using it will provide types to your users without asking them to load either L<Lexical::Types> or the type classes manually.
149 BEGIN { require Lexical::Types; }
152 eval 'package Str; package Int'; # The types you want to support
153 Lexical::Types->import(
154 as => sub { __PACKAGE__, 'new_' . lc($_[0]) }
159 Lexical::Types->unimport;
168 For C<perl> to be able to parse C<my Str $x>, the package C<Str> must be defined somewhere, and this even if you use the C<'as'> option to redirect to another package.
169 It's unlikely to find a workaround, as this happens deep inside the lexer, far from the reach of an extension.
171 Only one mangler or prefix can be in use at the same time in a given scope.
175 L<perl> 5.8, L<XSLoader>.
181 L<Attribute::Handlers>.
185 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
187 You can contact me by mail or on C<irc.perl.org> (vincent).
191 Please report any bugs or feature requests to C<bug-lexical-types at rt.cpan.org>, or through the web interface at L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Lexical-Types>. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
195 You can find documentation for this module with the perldoc command.
197 perldoc Lexical::Types
199 Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Lexical-Types>.
201 =head1 ACKNOWLEDGEMENTS
203 Inspired by Ricardo Signes.
205 =head1 COPYRIGHT & LICENSE
207 Copyright 2009 Vincent Pit, all rights reserved.
209 This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
213 1; # End of Lexical::Types