TITLE: ensuring identical typedefs in templates

(Newsgroups: comp.lang.c++, 18 Sep 99)


BUNJONGSAT: Waranun Bunjongsat

>But, what I'd like to guarantee is that I want to make sure template
>parameter "a" of X is the same as template parameter "a" of B.
>
>I know that we can do this.
>
>template <class a, class b, class c, class d, class e, template <class>
>class u>
>class B : public A<a,b>, private u<a,c,d,e> { ... }
>
>But I think it's a bad style. Because it increases the level of code
>bloat. Should avoid. However, I do not know other ways to do this.


NARAN: Siemel B. Naran <sbnaran@uiuc.edu>

I'm not sure if there will be additional code bloat.
But class B does have a few more template arguments.

The trick is to typedef a type twice in the same scope.
The compiler will complain if the two typedefs differ.

template <class a, class b, class x>
class B : public A<a,b>, private x
{
   typedef a                  a_type;
   typedef typename x::a_type a_type;
   public:
   private:
};