Logtalk 2.26.2 files.

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Logtalk/examples/reflection/reflection.lgt

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+
+/*
+In order to better grasp this example, draw a diagram of the hierarchy made of
+the three objects below with their instantiation and specialization relations.
+*/
+
+
+:- object(object,			% root of the inheritance graph
+	instantiates(class)).
+
+	:- info([
+		author is 'Paulo Moura',
+		version is 1.0,
+		date is 2000/4/22,
+		comment is 'Inheritance root for all objects.']).
+
+	:- public(strict_instance/0).
+	:- mode(strict_instance, zero_or_one).
+
+	:- public(print/0).
+	:- mode(print, one).
+
+	strict_instance.		% descendant instances of this class
+							% are, by default, strict instances
+	print :-
+		self(Self),
+		write('Object: '), writeq(Self), nl, nl,
+		write('  interface:'), nl,
+		forall(
+			::current_predicate(Predicate),
+			(write('    '), writeq(Predicate), nl)),
+		nl.
+
+:- end_object.
+
+
+:- object(class,			% default metaclass for all instantiable classes
+	instantiates(class),
+	specializes(abstract_class)).
+
+	:- info([
+		author 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 :-		% instances of this class are instantiable classes,
+		fail.				% not abstract classes
+
+:- end_object.
+
+
+:- object(abstract_class,	% default metaclass for all abstract classes
+	instantiates(class),
+	specializes(object)).
+
+	:- info([
+		author is 'Paulo Moura',
+		version is 1.0,
+		date is 2000/4/22,
+		comment is 'Default metaclass for all abstract classes.']).
+
+	:- public(metaclass/0).
+	:- mode(metaclass, zero_or_one).
+
+	:- public(abstract_class/0).
+	:- mode(abstract_class, zero_or_one).
+
+	abstract_class :-		% by default, descendant instances of this class are abstract
+		self(Self),			% classes except this class itself which is an instantiable class
+		Self \= abstract_class.
+
+	metaclass :-			% descendant instances of this class are metaclasses if
+		self(Self),			% their instances are themselves classes, i.e. if their 
+		once((				% instances accept the abstract_class/0 message 
+			instantiates_class(Class, Self),
+			Class::current_predicate(abstract_class/0))).
+
+	strict_instance :-		% instances of this class are not strict instances;
+		fail.				% they are classes
+
+:- end_object.