RE: [Opencxx-users] C++ design patterns

[SF M. E. <el...@us...>]

> I am under impression that each 'Ptree...::What()' returns something else
> (discriminator), similarily each 'Ptree...::Translate()' calls different
> method from Walker iface. Can you point out what classes have the same

Will abstract base classes be available for them like it was discussed for "AbstractWalker"?


> Again, this very much depends on the class semantics. Sometimes compiler
> generated implementations are OK. Please note, that due to GC even when
> class has value semantics and it contains (garbage collected) pointers,
> default copy ctor and assignment operator are ok. On the other hand,
> I suspect that in several places those functions should be blocked
> (by privation), but are not.

Please derive such classes from an interface class like "http://boost.org/libs/utility/utility.htm#Class_noncopyable".
I have not got detailed knowledge about your class library so far to decide where objects should not be copied. I hope that other developers are in a better position to do that.


> Some classes are designed to be derived from, some
> are "final". In particular classes that have value semantics (= define
> operator() and copy ctor and generally behaves as values) IMO almost
> always should be "final". But there may also be omissions. Please bring
> the names of these classes and I will comment on each of them
> particularily.

Value objects should not have any virtual methods.

I suggest to look for missing virtual destructors in all classes that contain virtual methods.


> The way that I would strongly recommend is to redesign components one by one
> and go from the old design to the new design in evolutionary steps. The
> smaller the components you replace, the easier it is to manage. Sometimes it
> pays off to refactor the old code to insulate some part of it before
> rewritting them. That way you have the running thing all the time.

Would you like to use the methodology "http://en.wikipedia.org/wiki/Extreme_Programming" that is supported by the tool "http://www.xplanner.org/"?


I suggest to use multiple inheritance in more cases.