:- object(regular_polygon,
instantiates(abstract_class),
specializes(polygon)).
:- info([
author is 'Paulo Moura',
version is 1.1,
date is 2004/1/8,
comment is 'Generic regular polygon.']).
:- public(side/1).
:- mode(side(?atom), zero_or_one).
:- info(side/1, [
comment is 'Regular polygon side length.',
argnames is ['Length']]).
side(1). % default side length
perimeter(Perimeter) :-
::nsides(Number),
::side(Side),
Perimeter is Number*Side.
:- end_object.
