Question

Is it possible to use a type Y which has been defined by a typedef inside of another type X, from within a third templated type Z, where X acts as a template parameter to Z?

This (non-compiling) pseudocode illustrates the desired behaviour:

struct X {
  typedef float Y;
};

template<typename T>
struct Z {
  void DoSomething(T::Y with_this);
};

Answer 1

Yes, it’s possible. You just need to let the compiler know that T::Y is a type because it depends on T:

void DoSomething(typename T::Y with_this);