]> Zitat von Jan Kybic <kybic@fel.cvut.cz>: > > I have a more fundamental question: Is inheritence actually useful > for > > anything? By which I mean, are there real world problems which are > > solved elegantly with inheritence which are otherwise difficult to > > solve? I'm not sure I've seen many. I have seen many very > tortuous > > class hierarchies though. > > > > Some personal thoughts: > > I think the OO methodology is good for creating reusable components > and maintaining a clean interface between them. [...] This also can be done with module system. Functors for example can help a lot here. > > I develop complex algorithms which consist of many building blocks. > Often, I need to try many variants before settling on a final > solution, sometimes there is not even any final solution - for each > subclass of a problem a different sub blocks might be appropriate. > It is a great time-saver if the building blocks can be swapped with > as little > change in the code as possible. [...] Modules and Functors are very good for this task. Just change the used module. If you need a certain flexibility that modules can not offer, for example, selecting certain implementations by user input, both paradigms can be combined: use OO-style for the selection of the seperate modules. > > The inheritance is then a convenient way of code reuse. But it's very overrated. Inheritance is the most obvious OO technique, and the way, how people tries to convince non-OO-programmers from the advantage of OO. But there are many other OO mechanisms, and ofteh it turns out that inheritance is used, where other OO-technics would be much better. With setting OO equal to inheritance, code will become weid and clumsy. So the advantages of OO can't be turned into advantages for the code. > Code reuse is important because it avoids code duplication. > And code duplication is bad because it makes maintenance hard. Yes, and modules and functors are very good here. > > However, I am not using the OO features of Ocaml much, mainly because > of the speed penalty. If you don't use them, it looks to me that you don't need them. If there really would be a need for OO in your code, you would use it, otherwise your program could not run as intended. So: you use OO for your own convenience (because you seem to be used to it), even other techniques are sufficient for gaibning the goal. I would use OO , when it is necessary, and not, if not. OO paradigm does solve some problems of non-OO code. But most of them can be done with modules and functional programming techniques (higher order functions) also. For many tasks OO is used like Bells-and-Whistles, and inheritance as an addiction. This makes code not better. Using that techinques that help, and not those, that are hype, will make code better. Ciao, Oliver