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MooseX-AttributeDefaults-0.02
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/ MooseX::AttributeDefaults

NAME

MooseX::AttributeDefaults - Role to provide default option for your attribute metaclasses

VERSION

Version 0.02

SYNOPSIS

Although you can do similar things by overriding attributes in subclasses of Moose::Meta::Attribute, there are a couple of gotchas (as of this writing, for instance, overriding 'is' does nothing at all). This role abstracts the implementation details of the available workarounds.

package My::Custom::Metaclass;
use Moose;

extends 'Moose::Meta::Attribute';
with    'MooseX::AttributeDefaults';

sub default_options {
  my ($class, $name) = @_;
  
  return (
    is      => 'ro',
    isa     => 'Str',
    default => "default value for $name";
  );
}

package Some::Class;
use Moose;

has 'attr' => (
  metaclass => 'My::Custom::Metaclass',
  predicate => 'has_attr',
);

# 'attr' is a ro string with "default value for attr" as its 
# default and a 'has_attr' predicate

### Or as a trait instead of a metaclass

package Acme::Common::Array;
use Moose::Role;

with qw(MooseX::AttributeDefaults);

sub default_options {
  is      => 'ro',
  isa     => 'ArrayRef',
  default => sub { [] },
}

package Some::Class;
use Moose;
use MooseX::AttributeHelpers;

has attr => (
  metaclass => 'Collection::Array',
  traits    => [qw(Acme::Common::Array)],
  provides  => {
    'push' => 'add_attr',
  },
);

REQUIRED METHODS

default_options

Return a list of options to default to. This is called as a class method with the attribute name as its only argument.

AUTHOR

Paul Driver, <frodwith at cpan.org>

COPYRIGHT & LICENSE

Copyright (C) 2008 Paul Driver.

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