NAME Lexical::Types - Extend the semantics of typed lexicals. VERSION Version 0.03 SYNOPSIS { package Str; } { package My::Types::Str; sub new { bless { }, shift } } use Lexical::Types as => sub { 'My::Types::' . $_[0] => 'new' }; my Str $x; # $x is now a My::Types::Str object { package My::Types::Int; sub TYPEDSCALAR { bless { }, shift } } use Lexical::Types; use constant Int => 'My::Types::Int'; my Int $y; # $y is now a My::Types::Int object DESCRIPTION This pragma allows you to hook the execution of typed lexicals declarations ("my Str $x"). In particular, it can be used to automatically tie or bless typed lexicals. It is not implemented with a source filter. FUNCTIONS "import [ as => [ $prefix | $mangler ] ]" Magically called when writing "use Lexical::Types". All the occurences of "my Str $x" in the current lexical scope will be changed to call at each run a given method in a given package. The method and package are determined by the parameter 'as' : * If it's left unspecified, the "TYPEDSCALAR" method in the "Str" package will be called. use Lexical::Types; my Str $x; # calls Str->TYPEDSCALAR * If a plain scalar $prefix is passed as the value, the "TYPEDSCALAR" method in the "${prefix}::Str" package will be used. use Lexical::Types as => 'My::'; # or "as => 'My'" my Str $x; # calls My::Str->TYPEDSCALAR * If the value given is a code reference $mangler, it will be called at compile-time with arguments 'Str' and 'TYPEDSCALAR' and is expected to return : * 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) ; use Lexical::Types as => sub { return $_[0] =~ /Str/ ? @_ : () }; my Str $y; # calls Str->TYPEDSCALAR my Int $x; # nothing special * or the desired package and method name, in that order (if any of those is "undef", the default value will be used instead). use Lexical::Types as => sub { 'My', 'new_' . lc($_[0]) }; my Str $x; # the coderef indicates to call My->new_str The initializer method receives an alias to the pad entry of $x in $_[1] and the original type name ("Str") in $_[2]. You can either edit $_[1] in place, in which case you should return an empty list, or return a new scalar that will be copied into $x. "unimport" Magically called when writing "no Lexical::Types". Turns the pragma off. INTEGRATION You can integrate Lexical::Types in your module so that using it will provide types to your users without asking them to load either Lexical::Types or the type classes manually. package MyTypes; BEGIN { require Lexical::Types; } sub import { eval 'package Str; package Int'; # The types you want to support Lexical::Types->import( as => sub { __PACKAGE__, 'new_' . lc($_[0]) } ); } sub unimport { Lexical::Types->unimport; } sub new_str { ... } sub new_int { ... } CAVEATS For "perl" to be able to parse "my Str $x", you need : * either the "Str" package to be defined ; * or for "Str" to be a constant sub returning a valid defined package. Those restrictions apply even if you use the 'as' option to redirect to another package, and are unlikely to find a workaround as this happens deep inside the lexer - far from the reach of an extension. Only one mangler or prefix can be in use at the same time in a given scope. DEPENDENCIES perl 5.8, XSLoader. SEE ALSO fields. Attribute::Handlers. AUTHOR Vincent Pit, "", . You can contact me by mail or on "irc.perl.org" (vincent). BUGS Please report any bugs or feature requests to "bug-lexical-types at rt.cpan.org", or through the web interface at . I will be notified, and then you'll automatically be notified of progress on your bug as I make changes. SUPPORT You can find documentation for this module with the perldoc command. perldoc Lexical::Types Tests code coverage report is available at . ACKNOWLEDGEMENTS Inspired by Ricardo Signes. Thanks Florian Ragwitz for suggesting the use of constants for types. COPYRIGHT & LICENSE Copyright 2009 Vincent Pit, all rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.