[GAP] Ada 2005 object.method doesn't always dispatch

[Cyrille Comar]

Tullio Vardanega wrote:
  If you have the patience of unzipping the project, browse
> through the code (which is basically Martin's and Cyrille's) and
> compile it, you will note an interesting malfunction in the compiler
> (in main.adb), which seems to dislike the object.method syntax
> for the example.

There is indeed one thing that looks fishy to me: I believe the compiler 
should accept the object.method notation for a class wide operation and 
it doesn't in your case. I'll open an internal ticket on this issue. I 
also wanted to comment on your comments:

<<
    --  this Operation1 is NON dispatching!
    -- procedure Operation1 (This : access Grand_Parent) is abstract;

    --  this Operation1 IS dispatching!
    procedure Operation1 (This : access Grand_Parent'Class) is abstract;
 >>

There is an interesting conflict of language here because strictly 
speaking the first Operation1 is dispatching (this is a primitive 
operation) whereas the second one is not dispatching (this is a 
class-wide operation). That is to say, a call to the first one would be 
dispatching if the actual is class-wide (since the operation is abstract 
no other actuals are permitted anyway). A call to the second one is 
never dispatching. Now, as this thread has shown, the situation is 
exactly inversed if you look at the calls in the body of those operations:
          This.Operation2;
Will dispatch in the latter case and not in the former. So calls inside 
a dispatching operation will have a tendancy not to dispatch whereas 
calls inside a classwide non-dispatching operation will have a tendancy 
to dispatch naturally.
How do you teach this to students without confusing them? ;-)