Re: Generic formal access types

[Ludovic Brenta <ludovic.brenta@insalien.org>]

Do you absolutely have to return null in one of the functions of your
generic package?  How about raising an exception instead?  Something
along the lines of:

generic
   type Element (<>) is private;
package List is
   No_Element_Error: Exception;
   type List is private;
   function Get_Element (L : List) return Element;
private
   type List is ... ;
end List;

package body List is
   function Get_Element (L : List) return Element is
   begin
      raise No_Element_Error; -- instead of return null
   end Get_Element;
end List;

I'm sure you've thought about that, but I'm curious to know why it
wouldn't work for you.

--
Ludovic Brenta.