# perldoc > Moose::Cookbook::Snack::Types

## NAME
    [Moose::Cookbook::Snack::Types](https://www.chedong.com/phpMan.php/perldoc/Moose%3A%3ACookbook%3A%3ASnack%3A%3ATypes/markdown) - Snippets of code for using Types and Type Constraints

## VERSION
    version 2.2207

## SYNOPSIS
      package Point;
      use Moose;

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

      package main;
      use [Try::Tiny](https://www.chedong.com/phpMan.php/perldoc/Try%3A%3ATiny/markdown);

      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](https://www.chedong.com/phpMan.php/perldoc/Moose%3A%3ACookbook%3A%3ABasics%3A%3APointAttributesAndSubclassing/markdown) 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](https://www.chedong.com/phpMan.php/perldoc/Try%3A%3ATiny/markdown) to catch this error message.

    Later, we get the [Moose::Meta::TypeConstraint](https://www.chedong.com/phpMan.php/perldoc/Moose%3A%3AMeta%3A%3ATypeConstraint/markdown) object from a [Moose::Meta::Attribute](https://www.chedong.com/phpMan.php/perldoc/Moose%3A%3AMeta%3A%3AAttribute/markdown) and use the
    [Moose::Meta::TypeConstraint](https://www.chedong.com/phpMan.php/perldoc/Moose%3A%3AMeta%3A%3ATypeConstraint/markdown) to check a value directly.

## SEE ALSO
    [Moose::Cookbook::Basics::Point_AttributesAndSubclassing](https://www.chedong.com/phpMan.php/perldoc/Moose%3A%3ACookbook%3A%3ABasics%3A%3APointAttributesAndSubclassing/markdown)
    [Moose::Util::TypeConstraints](https://www.chedong.com/phpMan.php/perldoc/Moose%3A%3AUtil%3A%3ATypeConstraints/markdown)
    [Moose::Meta::Attribute](https://www.chedong.com/phpMan.php/perldoc/Moose%3A%3AMeta%3A%3AAttribute/markdown)

## AUTHORS
    *   Stevan Little <<stevan@cpan.org>>

    *   Dave Rolsky <<autarch@urth.org>>

    *   Jesse Luehrs <<doy@cpan.org>>

    *   Shawn M Moore <<sartak@cpan.org>>

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

    *   Karen Etheridge <<ether@cpan.org>>

    *   Florian Ragwitz <<rafl@debian.org>>

    *   Hans Dieter Pearcey <<hdp@cpan.org>>

    *   Chris Prather <<chris@prather.org>>

    *   Matt S Trout <<mstrout@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.