Transforming a parameterization by two classes to a parameterization by one class

Question

The following code has a little bit of unpleasantness.

#include 

template struct PA1 {}; template struct QA1          


        

Answer 1

If you want type A to be automatically inferred, then no such modification is possible unless you have fn take an argument of type A (or A& or A* etc) and consequently force the user to pass in a value of that type.

On the other hand, if you don't mind forcing the caller to specify the template argument explicitly, then that syntax is already fine.

There's no happy medium.