Re: ambiguous method calling

From:
Carl Barron <cbarron413@adelphia.net>
Newsgroups:
comp.lang.c++.moderated
Date:
Wed, 19 Dec 2007 14:13:49 CST
Message-ID:
<191220070818561400%cbarron413@adelphia.net>
In article <20071218141105.C32366@buique.cin.ufpe.br>, Thiago Souto
Maior Cordeiro de Farias <tsmcf@cin.ufpe.br> wrote:

  Hi,
  I have troubles using templates with multiple inheritance, what
generated an
  error (in both Visual Studio 2005 and g++ 3.3.0) refering to an

ambiguous

  call. Ambiguous? the type is given in the calling function, but the
compiler
  needs the scope for the correct base where the desired method relies.
  There is any workaround to fix this problem?


  the problem is f(float), f(int),f(char) are all visible in class D and
they are non templated functions so the ambiquity.
  simplest solution is to write a metafunction to determine the proper
base class so the template selects the correct one

   template<class T> struct BaseClass;

   template<> struct BaseClass<float> {typedef A type;};
   template <> struct BaseClass<int> {typedef B type;};
   template <> struct BaseClass<char> {typedef C type;};

  class D : public A, public B, public C {
  public:
    template <typename T> void a(T t) {
       f(t) ; // change to

         Base?lass<T>::type::f(t);

    }
  };


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