--- name: "Moose::Meta::TypeConstraint" section: "3pm" platform: "linux" package: "perl-moose" version: "2.4001-2" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/Moose::Meta::TypeConstraint" --- # Moose::Meta::TypeConstraint(3pm) The Moose Type Constraint metaclass ## NAME Moose::Meta::TypeConstraint - The Moose Type Constraint metaclass ## VERSION version 2.4001 ## 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 \ - • יובל קוג'מן (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.