'final' function implementations in interface definition

[HOSOKAWA Kenchi]

Steve Schveighoffer Wrote:

> 
> f_twice can be a template:
> 
> void f_twice()(int i) { f(i); f(i); }
> 
> It's pretty much exactly what you want.  It should even work without 
> explicit instantiation.
> 
> -Steve

I have tried to replace final function in the interface with your code. finally I got following message.
Error: function I.f_twice!().f_twice template member function not allowed in interface I