Florian Ragwitz > Moose-2.0204 > Moose::Cookbook::Snack::Types

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NAME ^

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

VERSION ^

version 2.0204

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::Recipe1 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::Recipe1
Moose::Utils::TypeConstraints
Moose::Meta::Attribute

AUTHOR ^

Stevan Little <stevan@iinteractive.com>

COPYRIGHT AND LICENSE ^

This software is copyright (c) 2011 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.

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