Question

template <class M, class A> class C { std::list<M> m_List; ... } 

Is the above code possible? I would like to be able to do something similar.

Why I ask is that i get the following error:

Error 1 error C2079: 'std::_List_nod<_Ty,_Alloc>::_Node::_Myval' uses undefined class 'M'   C:\Program Files\Microsoft Visual Studio 9.0\VC\include\list    41 

Answer 1

My guess: you forward declared class M somewhere, and only declared it fully after the template instantiation.

My hint: give your formal template arguments a different name than the actual ones. (i.e. class M)

// template definition file #include <list>  template< class aM, class aT > class C {     std::list<M> m_List;     ... }; 

Example of a bad forward declaration, resulting in the mentioned error:

// bad template usage file causing the aforementioned error class M; ... C<M,OtherClass> c; // this would result in your error  class M { double data; }; 

Example of proper declaration, not resulting in the error:

// better template usage file class M { double data; }; // or #include the class header ...  C<M,OtherClass> c; // this would have to compile