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

## complements_object/2

#### Description

    complements_object(Category, Object)

Enumerates, by backtracking, all category–object pairs such that the category explicitly complements the object.

#### Template and modes

    complements_object(?category_identifier, ?object_identifier)

#### Errors

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

#### Examples

    | ?- complements_object(logging, employee).