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Logtalk - Object oriented extension to Prolog
Release 2.23.1
Copyright (c) 1998-2005 Paulo Moura. All Rights Reserved.
% start by loading the example:
| ?- logtalk_load(engines(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/2 ;
P = horsepower_rpm/2 ;
P = bore_stroke/2 ;
P = fuel/1
yes
| ?- coupe::current_predicate(P).
P = fuel/1 ;
% 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
% 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'
HP = 110
RPM = 5000