Re: Template question...

From:

"Alf P. Steinbach" <alfps@start.no>

Newsgroups:

comp.lang.c++

Date:

Tue, 14 Jul 2009 00:34:35 +0200

Message-ID:

<h3gd48$nfm$1@news.eternal-september.org>

* barcaroller:

I have two template classes, where one uses the first for a list type.

    template <typename T> class B
    {
    };

    template <typename T> class A
    {
        typedef list< B<T> >::iterator MyIterator_t; // <--- error here
    }

    Compiler error: type std::list, std::allocator > > is not derived
    from type A

Does anyone know what the error means and how to fix it?

The following compiles fine:

     #include <list>

     using namespace std;

     template <typename T> class B
     {
     };

     template <typename T> class A
     {
         typedef typename list< B<T> >::iterator MyIterator_t;
     };

     int main()
     {
         A<int>();
     }

I added a semicolon and a word to your code.

Check the FAQ item on dependent names (assuming there is such a FAQ item, but
check -- it's nearly always a good idea to consult the FAQ :-) ).

Cheers & hth.,

- Alf (helping others but would rather work, however, none in Norway want me)