Moose::Cookbook::Snack::Types - Snippets of code for using Types and Type Constraints |
Moose::Cookbook::Snack::Types - Snippets of code for using Types and Type Constraints
version 2.1605
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"; }
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.
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 |