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/sicstus/rectangle2.lgt

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+
+:- object(rectangle(_Width, _Height)).
+
+
+	:- info([
+		authors is 'Paulo Moura',
+		version is 1.0,
+		date is 2000/4/22,
+		comment is 'Parametric object for representing geometric rectangles.',
+		parnames is ['Width', 'Height']]).
+
+
+	:- public(width/1).
+
+	:- mode(width(?number), zero_or_one).
+
+	:- info(width/1, [
+		comment is 'Rectangle width.',
+		argnames is ['Width']]).
+
+
+	:- public(height/1).
+
+	:- mode(height(?number), zero_or_one).
+
+	:- info(height/1, [
+		comment is 'Rectangle height.',
+		argnames is ['Height']]).
+
+
+	:- public(area/1).
+
+	:- mode(area(-number), one).
+
+	:- info(area/1, [
+		comment is 'Rectangle area.',
+		argnames is ['Area']]).
+
+
+	width(Width) :-
+		parameter(1, Width).
+
+
+	height(Height) :-
+		parameter(2, Height).
+
+
+	area(Area) :-
+		::width(Width),
+		::height(Height),
+		Area is Width*Height.
+
+
+:- end_object.