]> > One of the nice things about C++ and Java is that with properly > designed classes, you don't need to worry about freeing resources > in complicated code, because the when the objects go out of scope > either normally or via an exception, they will clean themselves up. I believe this is a C++-specific idiom. Java doesn't have destructors, just finalizers that are called asynchronously by the GC. OCaml also has GC finalization (see below). > Given that Ocaml has objects, it would be useful to have this > idiom available to us. Is there a way to implement it, rather > than just waiting for the garbage collector? Yes: higher-order functions. For a file: let with_file_in filename action = let ic = open_in filename in try let res = action ic in close_in ic; res with x -> close_in ic; raise x For a mutex: let synchronize mut action = try Mutex.lock mut; let res = action () in Mutex.unlock mut; res with x -> Mutex.unlock mut; raise x You get the idea. > Also, since objects have initializers, do they have finializers? I > read the entire Oreilly book and didn't see any mention of them. > Reading the C code interface, it looks like you can associate a > finalizer function to clean up an abstract type, but can you do > this with normal Ocaml code? Yes. The function Gc.finalise lets you attach finalization code to any heap-allocated Caml value, not just objects. I'm not surprised it is not mentioned in the O'Reilly book, since this is a recent addition to the OCaml implementation. - Xavier Leroy ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners