Ada202X : Adding functors

[Martin <martin@thedowies.com>]

I'm increasingly using functors in my C++ life and they are very cool. I'd like to be able to use them in my Ada life too but the language doesn't support it - or can someone tell me I'm wrong?

I think it could be done by 'simply' allowing something like this:

package P is
   type T is tagged ...;
   function Create return T;
   procedure "()" (This : T; I : Integer);  -- The functor call
   function "()" (This : T) return Integer; -- Alternative functor that's a function
private
...
end P;

with P;
procedure Demo is
   My_T : P.T := P.Create
begin
   My_T (42);  -- call to procedure version
   if My_T () > 100 then ... end if;  -- call to function version
end Demo;

I guess one of the trickier bits of adding this would be the possible need to step away from the current Ada convention of not requiring empty parenthesis...but new language revisions always change the 'current' good style...

Any thoughts?

-- Martin