Moose::Meta::TypeConstraint

NAME
VERSION
DESCRIPTION
INHERITANCE
METHODS
BUGS
AUTHORS
COPYRIGHT AND LICENSE

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NAME

Moose::Meta::TypeConstraint − The Moose Type Constraint metaclass

VERSION

version 2.2014

DESCRIPTION

This class represents a single type constraint. Moose’s built-in type constraints, as well as constraints you define, are all stored in a Moose::Meta::TypeConstraint::Registry object as objects of this class.

INHERITANCE

“Moose::Meta::TypeConstraint” is a subclass of Class::MOP::Object.

METHODS

Moose::Meta::TypeConstraint−>new(%options)
This creates a new type constraint based on the provided %options:

•

name

The constraint name. If a name is not provided, it will be set to “__ANON__”.

•

parent

A “Moose::Meta::TypeConstraint” object which is the parent type for the type being created. This is optional.

•

constraint

This is the subroutine reference that implements the actual constraint check. This defaults to a subroutine which always returns true.

•

message

A subroutine reference which is used to generate an error message when the constraint fails. This is optional.

•

coercion

A Moose::Meta::TypeCoercion object representing the coercions to the type. This is optional.

•

inlined

A subroutine which returns a string suitable for inlining this type constraint. It will be called as a method on the type constraint object, and will receive a single additional parameter, a variable name to be tested (usually “$_” or “$_[0]”.

This is optional.

•

inline_environment

A hash reference of variables to close over. The keys are variables names, and the values are references to the variables.

$constraint−>equals($type_name_or_object)
Returns true if the supplied name or type object is the same as the current type.

$constraint−>is_subtype_of($type_name_or_object)
Returns true if the supplied name or type object is a parent of the current type.

$constraint−>is_a_type_of($type_name_or_object)
Returns true if the given type is the same as the current type, or is a parent of the current type. This is a shortcut for checking “equals” and “is_subtype_of”.

$constraint−>coerce($value)
This will attempt to coerce the value to the type. If the type does not have any defined coercions this will throw an error.

If no coercion can produce a value matching $constraint, the original value is returned.

$constraint−>assert_coerce($value)
This method behaves just like “coerce”, but if the result is not valid according to $constraint, an error is thrown.

$constraint−>check($value)
Returns true if the given value passes the constraint for the type.

$constraint−>validate($value)
This is similar to “check”. However, if the type is valid then the method returns an explicit “undef”. If the type is not valid, we call “$self−>get_message($value)” internally to generate an error message.

$constraint−>assert_valid($value)
Like “check” and “validate”, this method checks whether $value is valid under the constraint. If it is, it will return true. If it is not, an exception will be thrown with the results of “$self−>get_message($value)”.

$constraint−>name
Returns the type’s name, as provided to the constructor.

$constraint−>parent
Returns the type’s parent, as provided to the constructor, if any.

$constraint−>has_parent
Returns true if the type has a parent type.

$constraint−>parents
Returns all of the types parents as an list of type constraint objects.

$constraint−>constraint
Returns the type’s constraint, as provided to the constructor.

$constraint−>get_message($value)
This generates a method for the given value. If the type does not have an explicit message, we generate a default message.

$constraint−>has_message
Returns true if the type has a message.

$constraint−>message
Returns the type’s message as a subroutine reference.

$constraint−>coercion
Returns the type’s Moose::Meta::TypeCoercion object, if one exists.

$constraint−>has_coercion
Returns true if the type has a coercion.

$constraint−>can_be_inlined
Returns true if this type constraint can be inlined. A type constraint which subtypes an inlinable constraint and does not add an additional constraint “inherits” its parent type’s inlining.

$constraint−>create_child_type(%options)
This returns a new type constraint of the same class using the provided %options. The “parent” option will be the current type.

This method exists so that subclasses of this class can override this behavior and change how child types are created.

BUGS

See ” BUGS” in Moose for details on reporting bugs.

AUTHORS

	•		Stevan Little
	•		Dave Rolsky
	•		Jesse Luehrs
	•		Shawn M Moore
	•		×××× ×§××’×× (Yuval Kogman)
	•		Karen Etheridge
	•		Florian Ragwitz
	•		Hans Dieter Pearcey
	•		Chris Prather
	•		Matt S Trout

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.

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