MooseX::AttributeTree::Accessor - Moose accessor role for inheritance through the object tree

MooseX-AttributeTree documentation Contained in the MooseX-AttributeTree distribution.

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NAME

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MooseX::AttributeTree::Accessor - Moose accessor role for inheritance through the object tree

VERSION

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This document describes version 0.03 of MooseX::AttributeTree::Accessor, released November 14, 2010 as part of MooseX-AttributeTree version 0.03.

DESCRIPTION

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MooseX::AttributeTree::Accessor is the backend that does the work for the TreeInherit trait. See MooseX::AttributeTree for details.

AUTHOR

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Christopher J. Madsen <perl AT cjmweb.net>

Please report any bugs or feature requests to <bug-MooseX-AttributeTree AT rt.cpan.org>, or through the web interface at http://rt.cpan.org/Public/Bug/Report.html?Queue=MooseX-AttributeTree

You can follow or contribute to MooseX-AttributeTree's development at git://github.com/madsen/moosex-attributetree.git.

COPYRIGHT AND LICENSE

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This software is copyright (c) 2010 by Christopher J. Madsen.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

DISCLAIMER OF WARRANTY

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BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENSE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

MooseX-AttributeTree documentation Contained in the MooseX-AttributeTree distribution. 
#---------------------------------------------------------------------
package MooseX::AttributeTree::Accessor;
#
# Copyright 2009 Christopher J. Madsen
#
# Author: Christopher J. Madsen <perl@cjmweb.net>
# Created: October 9, 2009
#
# This program is free software; you can redistribute it and/or modify
# it under the same terms as Perl itself.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See either the
# GNU General Public License or the Artistic License for more details.
#
# ABSTRACT: Moose accessor role for inheritance through the object tree
#---------------------------------------------------------------------

our $VERSION = '0.03';

use MooseX::Role::Parameterized;

parameter qw(parent_link
  is       ro
  isa      Str
  required 1
);

parameter qw(fetch_method
  is       ro
  isa      Maybe[Str]
  required 1
);

parameter qw(default
  is       ro
  isa      Maybe[Value|CodeRef]
  required 1
);

role {
  my $parent_link  = $_[0]->parent_link;
  my $fetch_method = $_[0]->fetch_method;
  my $default      = $_[0]->default;

  # I haven't created inline versions of the methods yet:
  method 'is_inline' => sub { 0 };

  method '_generate_accessor_method' => sub {
    my $attr = (shift)->associated_attribute;
    my ($method, @args) = $fetch_method
        ? ($fetch_method, $attr->name)
        : ($attr->get_read_method);

    return sub {
      $attr->set_value($_[0], $_[1]) if scalar(@_) == 2;

      if ($attr->has_value($_[0])) {
        return $attr->get_value($_[0]);
      } else {
        my $result;
        if (my $parent = $_[0]->$parent_link) {
          $result = $parent->$method(@args);
        } # end if $parent
        return (defined $result ? $result :
                ref $default ? $_[0]->$default : $default);
      } # end else this object has no value for the attribute
    } # end anonymous accessor sub
  }; # end _generate_accessor_method

  method '_generate_reader_method' => sub {
    my $attr = (shift)->associated_attribute;
    my ($method, @args) = $fetch_method
        ? ($fetch_method, $attr->name)
        : ($attr->get_read_method);

    return sub {
      $attr->throw_error('Cannot assign a value to a read-only accessor',
                         data => \@_) if @_ > 1;

      if ($attr->has_value($_[0])) {
        return $attr->get_value($_[0]);
      } else {
        my $result;
        if (my $parent = $_[0]->$parent_link) {
          $result = $parent->$method(@args);
        } # end if $parent
        return (defined $result ? $result :
                ref $default ? $_[0]->$default : $default);
      } # end else this object has no value for the attribute
    } # end anonymous reader sub
  }; # end _generate_reader_method

}; # end role

#=====================================================================
# Package Return Value:

1;

__END__