Re: dynamic dispatch on operator arguments?

From: Alwyn (dt015a1979_at_mac.com.invalid)
Date: 11/05/04 

Date: Fri, 05 Nov 2004 21:01:18 +0000

In article <cmgmrn0m4r@enews4.newsguy.com>, Mark P <not@my.real.email>
wrote:
>
> Say I have a base class B and a derived class D.
>
> Now I have some other class C in which I want to provide two functions:
>
> void C::f(B* bObj);
> void C::f(D* dObj);
>
> The goal is that the version of f called should be determined by the
> dynamic type of its argument. So if I had
>
> C cObj;
> B *pD = new D();
> cObj.f(pD);
>
> then cObj.f(pD) should call the second (D*) version of the function even
> though the static type of pD is B*.
>
> Is such a thing possible? If so, how?

Both Coplien and Alexandrescu discuss how to implement multimethods in
their respective books, but it is far from trivial.

For Alexandrescu's solution, see:
<http://www.visualco.de/idiom/samples/Loki/html/c$$lib$Loki$Reference$Mu
ltiMetho8.html>

HTH

Alwyn

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