:- object(polygon,
instantiates(abstract_class),
specializes(object)).
:- info([
version is 1.1,
date is 2000/10/31,
author is 'Paulo Moura',
comment is 'Polygon predicates.']).
:- uses(list).
:- public(move/2).
:- mode(move(+integer, +integer), one).
:- public(number_of_sides/1).
:- mode(number_of_sides(?integer), zero_or_one).
:- private(position_/2).
:- dynamic(position_/2).
:- mode(position_(?integer, ?integer), zero_or_one).
:- public(position/2).
:- mode(position(?integer, ?integer), zero_or_one).
version is 2,
date is 1998/2/23,
comment is 'Default protocol for all polygons.']).
position(X, Y) :-
::position_(X, Y).
move(X, Y) :-
::retractall(position_(_, _)),
::assertz(position_(X, Y)).
trans_x(X) :-
::retractall(position_(_, Y)),
trans_y(Y) :-
::retractall(position_(X, _)),
default_init_option(position-(0, 0)).
default_init_option(Default) :-
^^default_init_option(Default).
process_init_option(position-(X, Y)) :-
::move(X, Y).
process_init_option(Option) :-
^^process_init_option(Option).
:- end_object.
