.. This file is part of Logtalk https://logtalk.org/ SPDX-FileCopyrightText: 1998-2024 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. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

.. rst-class:: align-right

built-in predicate

.. index:: pair: threaded_engine_next_reified/2; Built-in predicate .. _predicates_threaded_engine_next_reified_2:

threaded_engine_next_reified/2

Description

::

threaded_engine_next_reified(Engine, Answer)

Retrieves an answer from an engine and signals it to start computing the next answer. This predicate always succeeds and blocks until an answer becomes available. Answers are returned using the terms the(Answer), no, and exception(Error).

.. 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_next_reified(@nonvar, ?nonvar) - one

Errors

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

Examples

::

% get the next reified answer from the worker_1 engine: | ?- threaded_engine_next_reified(worker_1, Answer).

.. seealso::

:ref:predicates_threaded_engine_create_3, :ref:predicates_threaded_engine_next_2, :ref:predicates_threaded_engine_yield_1