Ray Blaak a �crit dans le message : m3hfcxjt22.fsf@ns58.infomatch.bc.ca... > OO programming being essentially about ADTs covers the most important and > worthwhile point. What makes OO programming different from ADTs, in least in my > opinion, is language support for inheritance and polymorphism. Certainly not. What you describe is classification, which is one way of organizing objects. Composition is another one, and there might be others to be invented. I would rather say that what makes OO is the fact that ADT's represent and are modelled after real-life objects, i.e. that a program is no more defined as a sequence of actions to be performed by a computer, but as a representation, a modelization, of the real world. FWIW. -- --------------------------------------------------------- J-P. Rosen (Rosen.Adalog@wanadoo.fr) Visit Adalog's web site at http://pro.wanadoo.fr/adalog