# `instantiates_class/2-3`

## Description

    instantiates_class(Instance, Class)
    instantiates_class(Instance, Class, Scope)

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

## Modes and number of proofs

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

## Errors

`Instance` is neither a variable nor a valid object identifier:
`type_error(object_identifier, Instance)`
`Class` is neither a variable nor a valid object identifier:
`type_error(object_identifier, Class)`
`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

    % check that the water_jug is an instante of state_space:
    | ?- instantiates_class(water_jug, state_space).

    % enumerate the state_space instances where the
    % instantiation relation is public:
    | ?- instantiates_class(Space, state_space, public).

See also

current_object/1, extends_object/2-3, specializes_class/2-3