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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 folder contains an alternative implementation of the family example, which in turn is a version of the classical family tree Prolog example.

This alternative solution defines a family/1 parametric object, providing predicates for common family relations like sister/2 and father/2. This parametric object allows concrete families to be plugged-in by defining the basic female, male, and parent relations as multifile predicates parameterized by the family database object. Several family objects can be loaded at the same time. Using a parametric object to query a family extended relations is convenient as the object parameter allows us to make the name of the concrete family easily available to any predicate.

The main advantage of this solution is that it avoids dynamic binding as found in the family example. Moreover, when this version is compiled in optimized mode, the multifile predicate clauses, which act as liking clauses, are inlined. The main downside of this solution is the boilerplate code that must be written (i.e., the multifile predicate definitions).