..
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   SPDX-FileCopyrightText: 1998-2026 Paulo Moura <pmoura@logtalk.org>
   SPDX-License-Identifier: Apache-2.0

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
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       http://www.apache.org/licenses/LICENSE-2.0

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.. rst-class:: align-right

**built-in predicate**

.. index:: pair: threaded_engine_self/1; Built-in predicate
.. _predicates_threaded_engine_self_1:

``threaded_engine_self/1``
==========================

Description
-----------

::

   threaded_engine_self(Engine)

Queries the name of engine calling the predicate. Fails if not called from
within an engine or if the argument doesn't unify with the engine name.

.. note::

   This predicate requires a :term:`backend Prolog compiler` providing
   compatible multi-threading primitives. The value of the read-only
   :ref:`engines <flag_engines>` flag is set to ``supported`` when that
   is the case.

Modes and number of proofs
--------------------------

::

   threaded_engine_self(?nonvar) - zero_or_one

Errors
------

(none)

Examples
--------

::

   % find the name of the engine making the query:
   ..., threaded_engine_self(Engine), ...

   % check if the the engine making the query is worker_1:
   ..., threaded_engine_self(worker_1), ...

.. seealso::

   :ref:`predicates_threaded_engine_create_3`,
   :ref:`predicates_threaded_engine_destroy_1`,
   :ref:`predicates_threaded_engine_1`
