Logtalk reference manual
Built-in predicate: threaded_engine/1
Contents > Reference Manual > Built-in Predicates > threaded_engine/1

## threaded_engine/1

#### Description

    threaded_engine(Engine)

Enumerates, by backtracking, all existing engines. Engine names shall be regarded as opaque terms; users shall not rely on its type.

#### Template and modes

    threaded_engine(?nonvar)

#### Errors

`(none)`

#### Examples

Check that an engine named `worker_1` exists:
  `threaded_engine(worker_1)`
Write the names of all existing engines:
  `forall(threaded_engine(Engine), (writeq(Engine), nl))`

#### See also

`threaded_engine_create/3`, `threaded_engine_self/1`, `threaded_engine_destroy/1`