/ 
Moose-2.2206
River stage four • 2916 direct dependents • 4004 total dependents
326 ++
/ Moose::Cookbook::Snack::Types

NAME

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

VERSION

version 2.2206

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@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.