NAME¶
Moose::Cookbook::Snack::Types - Snippets of code for using Types and Type
Constraints
VERSION¶
version 2.0603
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::Utils::TypeConstraints
- Moose::Meta::Attribute
AUTHOR¶
Moose is maintained by the Moose Cabal, along with the help of many
contributors. See "CABAL" in Moose and "CONTRIBUTORS" in
Moose for details.
COPYRIGHT AND LICENSE¶
This software is copyright (c) 2012 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.