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This file is part of Logtalk <https://logtalk.org/>  
Copyright 1998-2020 Paulo Moura <pmoura@logtalk.org>

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.
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% start by loading the example:

| ?- logtalk_load(carengines(loader)).
...


% both cars provide the same interface, declared in the protocol
% that is implemented by the categories imported by each object:

| ?- sedan::current_predicate(P).

P = reference/1 ;
P = capacity/1 ;
P = cylinders/1 ;
P = horsepower_rpm/2 ;
P = bore_stroke/2 ;
P = fuel/1
yes


| ?- coupe::current_predicate(P).

P = reference/1 ;
P = capacity/1 ;
P = cylinders/1 ;
P = horsepower_rpm/2 ;
P = bore_stroke/2 ;
P = fuel/1 ;
yes


% the sedan engine properties are the ones defined in the corresponding 
% imported category (classic):

| ?- sedan::(reference(Name), cylinders(Cylinders), horsepower_rpm(HP, RPM)).

Name = 'M180.940'
Cylinders = 6
HP = 94
RPM = 4800 
yes


% the coupe engine properties are the ones defined in the corresponding 
% imported category (sport) plus the ones inherited from the top category 
% (classic) which are not overridden:

| ?- coupe::(reference(Name), cylinders(Cylinders), horsepower_rpm(HP, RPM)).

Name = 'M180.941'
Cylinders = 6
HP = 115
RPM = 3657 
yes
