.. 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

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.. rst-class:: align-right

built-in predicate

.. index:: pair: create_protocol/3; Built-in predicate .. _predicates_create_protocol_3:

create_protocol/3

Description

::

create_protocol(Identifier, Relations, Directives)

Creates a new, dynamic, protocol. This predicate is often used as a primitive to implement high-level protocol creation methods.

Note that, when opting for runtime generated protocol identifiers, it's possible to run out of identifiers when using a :term:`backend Prolog compiler` with bounded integer support. The portable solution, when creating a large number of dynamic protocols in long-running applications, is to recycle, whenever possible, the identifiers.

When using Logtalk multi-threading features, predicates calling this built-in predicate may need to be declared synchronized in order to avoid race conditions.

Modes and number of proofs

::

create_protocol(?protocol_identifier, @list(protocol_relation), @list(protocol_directive)) - one

Errors

| Either Relations or Directives is a variable: | instantiation_error | Identifier is neither a variable nor a valid protocol identifier: | type_error(protocol_identifier, Identifier) | Identifier is already in use: | permission_error(modify, category, Identifier) | permission_error(modify, object, Identifier) | permission_error(modify, protocol, Identifier) | Relations is neither a variable nor a proper list: | type_error(list, Relations) | Repeated entity relation clause: | permission_error(repeat, entity_relation, extends/1) | Directives is neither a variable nor a proper list: | type_error(list, Directives)

Examples

::

| ?- create_protocol( logging, [extends(monitoring)], [public([log_file/1, log_on/0, log_off/0])] ).

.. seealso::

:ref:predicates_abolish_protocol_1, :ref:predicates_current_protocol_1, :ref:predicates_protocol_property_2, :ref:predicates_conforms_to_protocol_2_3, :ref:predicates_extends_protocol_2_3, :ref:predicates_implements_protocol_2_3