Include Paulo Moura's Logtalk OO LP system

git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@53 b08c6af1-5177-4d33-ba66-4b1c6b8b522a

Logtalk/examples/polygons/polygon.lgt

@@ -0,0 +1,71 @@
+
+:- object(polygon,
+	instantiates(abstract_class),
+	specializes(object)).
+
+
+	:- info([
+		version is 1.1,
+		date is 2000/10/31,
+		authors 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).
+
+
+	:- info([
+		version is 2,
+		date is 1998/2/23,
+		authors is 'Paulo Moura',
+		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)),
+		::assertz(position_(X, Y)).
+
+
+	trans_y(Y) :-
+		::retractall(position_(X, _)),
+		::assertz(position_(X, Y)).
+
+
+	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.
+