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

## threaded_engine_answer/2

#### Description

    threaded_engine_answer(Engine, Answer)

Retrieves an answer from an engine. When the engine goal is running, this predicate blocks until an answer becomes available. The predicate fails when there are no more solutions to the engine goal.

#### Template and modes

    threaded_engine_answer(@nonvar, ?term)

#### Errors

Engine is a variable:
  `instantiation_error`
Engine is neither a variable nor the name of an existing engine:
  `existence_error(engine, Engine)`

#### Examples

Returns the atom `ready` as an engine answer:
  `threaded_engine_return(ready)`

#### See also

`threaded_engine_create/3`, `threaded_engine_return/1`