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/reflection/class.lgt

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+
+:- object(class,
+	instantiates(class),
+	specializes(abstract_class)).
+
+
+	:- info([
+		authors is 'Paulo Moura',
+		version is 1.0,
+		date is 2000/4/22,
+		comment is 'Instantiation root and default metaclass for all classes.']).
+
+
+	:- public(new/1).
+	:- mode(new(+object), zero_or_one).
+
+	:- public(delete/1).
+	:- mode(delete(+object), zero_or_one).
+
+	:- public(instances/1).
+	:- mode(instances(-list), one).
+
+
+	new(Object) :-
+		self(Self),
+		create_object(Object, [instantiates(Self)], [], []).
+
+
+	delete(Object) :-
+		self(Self),
+		instantiates_class(Object, Self),
+		\+ instantiates_class(_, Object),
+		\+ specializes_class(_, Object),
+		abolish_object(Object).
+
+
+	instances(Instances) :-
+		self(Self),
+		findall(Instance, instantiates_class(Instance, Self), Instances).
+
+
+	abstract_class :-
+		fail.
+
+
+:- end_object.