Perl6Attribute - An example attribute metaclass for Perl 6 style attributes

Moose documentation Contained in the Moose distribution.

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NAME

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Perl6Attribute - An example attribute metaclass for Perl 6 style attributes

SYNOPSIS

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  package Foo;

  Foo->meta->add_attribute(Perl6Attribute->new('$.foo'));
  Foo->meta->add_attribute(Perl6Attribute->new('@.bar'));    
  Foo->meta->add_attribute(Perl6Attribute->new('%.baz'));    

  sub new  {
      my $class = shift;
      $class->meta->new_object(@_);
  }

DESCRIPTION

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This is an attribute metaclass which implements Perl 6 style attributes, including the auto-generating accessors.

This code is very simple, we only need to subclass Class::MOP::Attribute and override &new. Then we just pre-process the attribute name, and create the accessor name and default value based on it.

More advanced features like the handles trait (see A12 in Perl6::Bible) can be accomplished as well doing the same pre-processing approach. This is left as an exercise to the reader though (if you do it, please send me a patch though, and will update this).

AUTHORS

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Stevan Little <stevan@iinteractive.com>

Yuval Kogman <nothingmuch@woobling.com>

COPYRIGHT AND LICENSE

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Copyright 2006-2008 by Infinity Interactive, Inc.

http://www.iinteractive.com

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

Moose documentation Contained in the Moose distribution. 
package # hide the package from PAUSE
    Perl6Attribute;

use strict;
use warnings;

our $VERSION = '0.02';

use base 'Class::MOP::Attribute';

Perl6Attribute->meta->add_around_method_modifier('new' => sub {
	my $cont = shift;
    my ($class, $attribute_name, %options) = @_;
    
    # extract the sigil and accessor name
    my ($sigil, $accessor_name) = ($attribute_name =~ /^([\$\@\%])\.(.*)$/);
    
    # pass the accessor name
    $options{accessor} = $accessor_name;
    
    # create a default value based on the sigil
    $options{default} = sub { [] } if ($sigil eq '@');
    $options{default} = sub { {} } if ($sigil eq '%');        
    
    $cont->($class, $attribute_name, %options);
});

1;

__END__