Re: Yet another inheritance vs containment question

henrik wrote:

> On a more general note, let's say we have
> 
> class A: private B, public C
> {
>    // ctor
>    A(param 1, param 2) : B(param 1, param 2), C(method from B, ...)
> {...}
>    ...
> }
> 
> where "method from B" returns a value that depends on param 1 and
> param 2. This might all be just theoretical (all though I think not,
> the code at the top is almost such a construct). Does anyone have some
> thoughts on a design like this? Does anyone have some real life code
> examples that illustrates this construct in practice?

Most of the time, we use IS_A to denote an inheritance relationship, HAS_A
for a containment relationship, and in this case, the relationship between
A and B is denoted by USES_FOR_IMPLEMENTATION. Doing it this way is
convenenient when implementing the class because there is no need to create
a data member and you do not need constructs as:

        B b;
        ....
        b.doThis();
        b.doThat();

to make it work. The simple

        doThis();
        doThat();

will suffice (provided that C does not have them also).

-- 
Ruurd
.o.
..o
ooo

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