Re: Discriminant within discriminants

["Jeffrey R. Carter" <spam.not.jrcarter@acm.not.spam.org>]

stuart clark wrote:
> I tried exactly as you have both suggested but i get a gnat compile
> error of
> 
> "Acknowledgements does not match any discriminant"

Interesting. After correcting some obvious errors, I get

message_test.adb:7:26: anonymous arrays not allowed as components

Correcting that, I get

message_test.adb:25:04: warning: variable "Msg" is not referenced

The code is

procedure Message_Test is
    package Message_Types is
       type Id_Type is range 1 .. 8;

       type Acks is new Boolean;

       type Ack_List is array (Id_Type range <>) of Acks;

       type Dispense_Ack (Size : Id_Type := Id_Type'First) is record
          Dispense_Acks : Ack_List (1 .. Size);
       end record;

       type Message_Types is
          (Dispense_Acknowledgement, Dispense_Request);

       type In_Messages (Kind : Message_Types := Message_Types'First) is
       record
          case Kind is
          when Dispense_Acknowledgement =>
             Acknowledgements : Dispense_Ack;
          when Dispense_Request =>
                Request : Integer;
          end case;
       end record;
    end Message_Types;

    Msg : Message_Types.In_Messages :=
       (Kind => Message_Types.Dispense_Acknowledgement,
       Acknowledgements =>
       (Size => 8,
        Dispense_Acks => (1 .. 8 => Message_Types.Acks'First) ) );
begin -- Message_Test
    null;
end Message_Test;

This is with MinGW GNAT 3.4.2.

-- 
Jeff Carter
"I would never want to belong to any club that
would have someone like me for a member."
Annie Hall
41