Moose::Meta::TypeConstraint(3)

NAME
Moose::Meta::TypeConstraint - The Moose Type Constraint metaclass

VERSION
version 2.2009

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 <stevan.little@iinteractive.com>

•   Dave Rolsky <autarch@urth.org>

•   Jesse Luehrs <doy@tozt.net>

•   Shawn M Moore <code@sartak.org>

•   יובל קוג'מן (Yuval Kogman) <nothingmuch@woobling.org>

•   Karen Etheridge <ether@cpan.org>

•   Florian Ragwitz <rafl@debian.org>

•   Hans Dieter Pearcey <hdp@weftsoar.net>

•   Chris Prather <chris@prather.org>

•   Matt S Trout <mst@shadowcat.co.uk>

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.