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   Copyright 1998-2019 Paulo Moura <pmoura@logtalk.org>

   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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.. index:: threaded_cancel/1
.. _predicates_threaded_cancel_1:

threaded_cancel/1
=================

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

::

   threaded_cancel(Tag)

Cancels a tagged threaded call. When there is no asynchronous call with the
given tag, calling this predicate succeeds assuming the asynchronous call
have already terminated or canceled. The threaded call identifier tag is
generated by calls to the :ref:`threaded_call/2 <predicates_threaded_call_1_2>`
and :ref:`threaded_once/2 <predicates_threaded_once_1_2>` predicates. Tags
shall be regarded as an opaque term; users shall not rely on its type.

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

::

   threaded_cancel(+nonvar) - one

Errors
------

| Tag is a variable:
|     ``instantiation_error``

Examples
--------

(none)

.. seealso::

   :ref:`predicates_threaded_call_1_2`,
   :ref:`predicates_threaded_exit_1_2`,
   :ref:`predicates_threaded_ignore_1`,
   :ref:`predicates_threaded_once_1_2`,
   :ref:`predicates_threaded_1`
