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This file is part of Logtalk https://logtalk.org/ SPDX-FileCopyrightText: 1998-2023 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.

To load this example and for sample queries, please see the SCRIPT.txt file.

This is a simple example illustrating the concept of prototypes, which provide an alternative to classes for object-oriented programming, using characters from the Alf television sitcom. Logtalk supports both classes and prototypes. It can be used as either a prototype-based language or a class-based language. Moreover, prototypes and classes can be freely used in the same application.

Class-based OOP languages are far more popular and, unfortunately, many books and teaching materials equate OOP languages with class-based OOP languages. Some examples of other prototype-based OOP languages include Self, JavaScript, Io, NewtonScript, Lua, and Slate.