---

jupyter: jupytext: text_representation: extension: .md format_name: markdown format_version: '1.3' jupytext_version: 1.16.7 kernelspec: display_name: Logtalk language: logtalk name: logtalk_kernel ---

<!--

This file is part of Logtalk https://logtalk.org/ SPDX-FileCopyrightText: 1998-2025 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. -->

Design pattern: Mediator

Description: "Defines an object that encapsulates how a set of objects interact. Mediator promotes loose coupling by keeping objects from referring to each other explicitly, and it lets you vary their interaction independently."

This pattern can be used with both classes and prototypes.

Print Logtalk, Prolog backend, and kernel versions (if running as a notebook):

%versions

Start by loading the design pattern sample implementation:

logtalk_load(design_patterns('behavioral/mediator/loader')).

First, click the "book" button:

book_button::click.

<!-- book_button disabled view_button enabled search_button enabled booking...

true. -->

Next, click the "view" button:

view_button::click.

<!-- book_button enabled view_button disabled search_button enabled viewing...

true. -->

Finally, click the "search" button:

search_button::click.

<!-- book_button enabled view_button enabled search_button disabled searching...

true. -->