Re: Ada generics and private type operations

[Simon Wright <simon@pushface.org>]

"Adam Beneschan" <adam@irvine.com> writes:

> Silly me.  I got so distracted by the presence of bird tracks all over
> my source that I forgot: you *can't* say ">=" => ">=" five times in
> your instantiation, because the thing on the left of the => can't be
> ambiguous.
>
> In fact, if you have more than one "with function >=" in your generic
> formal, then you can't say ">=" => anything, even once.  Either you
> have to let all of them default, or you have to use positional notation
> when you're instantiating (12.3(9)).  Actually, it's occurred to me
> that maybe this was your problem?

This is possibly a case for generic signature packages.

   generic
      type T is private;
      with function ">=" (L, R : T) return Boolean is <>;
   package Type_Signature is end Type_Signature;

   with Type_Signature;
   generic
      with package A is new Type_Signature (<>);
      with package B is new Type_Signature (<>);
   package User is
      function "<" (L, R : A.T) return Boolean;
   end User;

   package body User is
      function "<" (L, R : A.T) return Boolean is
      begin
         return not A.">=" (L, R);
      end "<";
   end User;