Moose::Cookbook::Snack::Types(3pm)
NAME
Moose::Cookbook::Snack::Types - Snippets of code for using Types and
Type Constraints
SYNOPSIS
package Point;
use Moose;
has 'x' => ( isa => 'Int', is => 'ro' );
has 'y' => ( isa => 'Int', is => 'rw' );
package main;
my $point = eval { Point->new( x => 'fifty', y => 'forty' ); };
if ($@) {
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 "eval" to catch this error message in $@.
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
Jess Robinson <cpan@desert-island.me.uk>
COPYRIGHT AND LICENSE
Copyright 2006-2010 by Infinity Interactive, Inc.
<http://www.iinteractive.com>
- This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.