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

## threaded_engine_next/2

#### Description

    threaded_engine_next(Engine, Answer)

Retrieves the next answer from an engine. This predicate blocks until an answer becomes available. The predicate fails when there are no more solutions to the engine goal. If the engine goal throws an exception, calling this predicate will re-throw the exception and subsequent calls will fail.

#### Template and modes

    threaded_engine_next(@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

Gets the next engine answer:
  `threaded_engine_next(worker_1, Answer)`

#### See also

`threaded_engine_create/3`, `threaded_engine_next_reified/2`, `threaded_engine_yield/1`