Logtalk reference manual
Built-in predicate: extends_object/2-3
Contents > Reference Manual > Built-in Predicates > extends_object/2-3

## extends_object/2-3

#### Description

    extends_object(Prototype, Parent)
    extends_object(Prototype, Parent, Scope)

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

#### Template and modes

    extends_object(?object_identifier, ?object_identifier)
    extends_object(?object_identifier, ?object_identifier, ?scope)

#### Errors

Prototype is neither a variable nor a valid object identifier:
  `type_error(object_identifier, Prototype)`
Parent is neither a variable nor a valid object identifier:
  `type_error(object_identifier, Parent)`
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

    | ?- extends_object(Object, state_space).

    | ?- extends_object(Object, list, public).

#### See also

`current_object/1`, `instantiates_class/2-3`, `specializes_class/2-3`