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



NAME

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


VERSION

version 2.1605


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 the Moose::Cookbook::Basics::Point_AttributesAndSubclassing manpage 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 the Try::Tiny manpage to catch this error message.

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


SEE ALSO

the Moose::Cookbook::Basics::Point_AttributesAndSubclassing manpage
the Moose::Util::TypeConstraints manpage
the Moose::Meta::Attribute manpage


AUTHORS


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.

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