phpman > perldoc > Moose::Cookbook::Snack::Types

NAME
    Moose::Cookbook::Snack::Types - Snippets of code for using Types and Type Constraints

VERSION
    version 2.2200

SYNOPSIS
      package Point;
      use Moose;

      has 'x' => ( isa => 'Int', is => 'ro' );
      has 'y' => ( isa => 'Int', is => 'rw' );

      package main;
      use Try::Tiny;

      my $point = try {
          Point->new( x => 'fifty', y => 'forty' );
      }
      catch {
          print "Oops: $_";
      };

      my $point;
      my $xval             = 'forty-two';
      my $xattribute       = Point->meta->find_attribute_by_name('x');
      my $xtype_constraint = $xattribute->type_constraint;

      if ( $xtype_constraint->check($xval) ) {
          $point = Point->new( x => $xval, y => 0 );
      }
      else {
          print "Value: $xval is not an " . $xtype_constraint->name . "\n";
      }

DESCRIPTION
    This is the Point example from Moose::Cookbook::Basics::Point_AttributesAndSubclassing with type
    checking added.

    If we try to assign a string value to an attribute that is an "Int", Moose will die with an
    explicit error message. The error will include the attribute name, as well as the type
    constraint name and the value which failed the constraint check.

    We use Try::Tiny to catch this error message.

    Later, we get the Moose::Meta::TypeConstraint object from a Moose::Meta::Attribute and use the
    Moose::Meta::TypeConstraint to check a value directly.

SEE ALSO
    Moose::Cookbook::Basics::Point_AttributesAndSubclassing
    Moose::Util::TypeConstraints
    Moose::Meta::Attribute

AUTHORS
    *   Stevan Little <stevan AT cpan.org>

    *   Dave Rolsky <autarch AT urth.org>

    *   Jesse Luehrs <doy AT cpan.org>

    *   Shawn M Moore <sartak AT cpan.org>

    *   יובל קוג'מן (Yuval Kogman) <nothingmuch AT woobling.org>

    *   Karen Etheridge <ether AT cpan.org>

    *   Florian Ragwitz <rafl AT debian.org>

    *   Hans Dieter Pearcey <hdp AT cpan.org>

    *   Chris Prather <chris AT prather.org>

    *   Matt S Trout <mstrout AT cpan.org>

COPYRIGHT AND LICENSE
    This software is copyright (c) 2006 by Infinity Interactive, Inc.

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