TITLE: reference to a void

[ Here is an interesting argument for allowing a reference to
  a void. -adc ]

PROBLEM: Paul D. DeRocco <pderocco@ix.netcom.com>

 The C++ standard doesn't allow a return statement with an expression to 
 be used in a function whose return type is void.
 
 I suggest that it should be legal to return a void expression from a 
 function whose type is void. Why? It can be useful in templates. 
 Consider the following:
 
     template <class T, class R> class Functor {
     public:
         R& operator()() { return (obj.*mem)(); }
         Functor(T& o, R& (T::*m)()): obj(o), mem(m) {}
     private:
         T& obj;
         R& (T::*mem)();
     }
 
 This defines a functor containing a pointer to an object to be operated 
 on, and a pointer to a member function defined for that object. It 
 should work for any member function that takes no arguments and returns 
 a result. Unfortunately, it won't work for a member function that 
 returns void. If return were modified as described above, this function 
 template would work for member functions that return void as well.


RESPONSE: bs@research.att.com (Bjarne Stroustrup), 25 Feb 96

I have written a note to the committee formally proposing this. The reason
stated was roughly the one above. In addition - and for the same reason -
I proposed to allow an expression of type void to be used as the argument
of a function taking no argument.

There is no guarantee that the committee will accept this or even that the
committee will consider it (though clearly I think the committee ought to).