🚀 go-pugleaf

>Ari Juhani Huttunen
>
>How do you use multiple inheritance and pointers to a base class object at 
>the same time? Suppose you have many different classes from which you wish
>to construct objects using multiple inheritance and you also wish to access
>these objects through a pointer to their common base class. Example:
>
>Animal - AnimalWithWingsAndTeeth
>       - AnimalWithWingsAndFeet
>       - AnimalWithFeetAndScales
>          ...
>
>You access these through a pointer to Animal. You have implemented classes
>named Wings, Teeth, Feet, Scales that implement functions fly, bite, run,
>protect. (And NoWings, NoTeeth, NoFeet, NoScales that do not.)
>
>The easy way to proceed would be:
>
>class Animal {
>public:
>  virtual fly() = 0;
>  virtual bite() = 0;
>  virtual run() = 0;
>  virtual protect() = 0;
>};
>
>class AnimalWithWingsAndTeeth : 
>  public Wings, public Teeth, public NoFeet, NoScales
>{};
>
. . .

Maybe I'm missing your point, but the base class should not contain
all the things that the derived classes need.  The way you are using
Animal, a base class "Object" would need to have all the fields and
methods that any program would ever need (say, such a class should
be part of the C++ language definition, and so all that coders would
need to do is decide what not to use ... :-).

An AnimalWithWingsAndTeeth should inherit Animal and add Wings and Teeth,
not get rid of run.

Please re-post with a good example of the use of what you are talking
about, your example seems an example of bad OO design, not of a
difficulty in a language.

This was not ment as a flame.


   jim miller
   jamiller@hpmpeb7.cup.hp.com
   (a.k.a James A. Miller; Jim the JAM; stupid; @!?$$!; ... )
   Anything I say will be used against me ...
   But my company doesn't know or approve or condone anything of mine here.