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.. rst-class:: align-right

built-in predicate

.. index:: pair: specializes_class/2-3; Built-in predicate .. _predicates_specializes_class_2_3:

specializes_class/2-3

Description

::

specializes_class(Class, Superclass) specializes_class(Class, Superclass, Scope)

Enumerates, by backtracking, all pairs of objects such that the first one specializes the second. The relation scope is represented by the atoms public, protected, and private.

Modes and number of proofs

::

specializes_class(?object_identifier, ?object_identifier) - zero_or_more specializes_class(?object_identifier, ?object_identifier, ?scope) - zero_or_more

Errors

| Class is neither a variable nor a valid object identifier: | type_error(object_identifier, Class) | Superclass is neither a variable nor a valid object identifier: | type_error(object_identifier, Superclass) | Scope is neither a variable nor an atom: | type_error(atom, Scope) | Scope is an atom but an invalid entity scope: | domain_error(scope, Scope)

Examples

::

% enumerate the state_space subclasses: | ?- specializes_class(Subclass, state_space).

% enumerate the state_space subclasses where the % specialization relation is public: | ?- specializes_class(Subclass, state_space, public).

.. seealso::

:ref:predicates_current_object_1, :ref:predicates_extends_object_2_3, :ref:predicates_instantiates_class_2_3