..
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   Copyright 1998-2021 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

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.. index:: pair: multifile/1; Directive
.. _directives_multifile_1:

``multifile/1``
===============

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

::

   multifile(Name/Arity)
   multifile((Name/Arity, ...))
   multifile([Name/Arity, ...])

   multifile(Entity::Name/Arity)
   multifile((Entity::Name/Arity, ...))
   multifile([Entity::Name/Arity, ...])

   multifile(Module:Name/Arity)
   multifile((Module:Name/Arity, ...))
   multifile([Module:Name/Arity, ...])

   multifile(Name//Arity)
   multifile((Name//Arity, ...))
   multifile([Name//Arity, ...])

   multifile(Entity::Name//Arity)
   multifile((Entity::Name//Arity, ...))
   multifile([Entity::Name//Arity, ...])

   multifile(Module:Name//Arity)
   multifile((Module:Name//Arity, ...))
   multifile([Module:Name//Arity, ...])

Declares multifile predicates and multifile grammar rule non-terminals. In the
case of object or category multifile predicates, the predicate (or non-terminal)
must also have a :term:`scope directive <predicate scope directive>` in the
object or category holding its *primary declaration* (i.e. the declaration
without the ``Entity::`` prefix). Entities holding multifile predicate primary
declarations must be compiled and loaded prior to any entities contributing
with clauses for the multifile predicates (to prevent using multifile
predicates to break entity encapsulation).

Protocols cannot declare or define multifile predicates as protocols cannot
contain predicate definitions.

.. warning::

   Some backend Prolog compilers declare ``multifile`` as an operator
   for a lighter syntax. But this makes the code non-portable and is
   a practice best avoided.

Template and modes
------------------

::

   multifile(+qualified_predicate_indicator_term)
   multifile(+qualified_non_terminal_indicator_term)

Examples
--------

::

   :- multifile(table/3).
   :- multifile(user::hook/2).

.. seealso::

   :ref:`directives_public_1`,
   :ref:`directives_protected_1`,
   :ref:`directives_private_1`,
   :ref:`methods_predicate_property_2`
