Re: Disriminant question - Waiting desperately for solution :-(

Re: Disriminant question - Waiting desperately for solution :-(

[prashna]

> 
> The rule is that you can't change the discriminant if the object was
> declared with an explicit discriminant value.
> 

Thanks all for helping.

Here is my original code(which I should I have posted earlier but
could not because this is highly confidential and hence I am showing
only part of the code.Hope u ppl understand.) and a runtime error
(discriminant error) is raising.

procedure CLEAR_DISCON (PRIMARY_FPLN_PARAM  : in out       
SERVER_TYPES.T_PRIMARY_FPLN;
                        DISCON              : in
SERVER_TYPES.T_LEG_INDEX;
                        REQUEST_STATUS      : out
SERVER_TYPES.T_REQUEST_STATUS;
                        MODIFICATION_REPORT : out
SERVER_TYPES.T_FPLN_MODIF_ORIGIN) is
   L_TERM : SERVER_TYPES.T_TERM;
...
...
 begin
....
....
      L_TERM := (LEG_TYPE => SERVER_TYPES.TF, 
                 FIX =>
PRIMARY_FPLN_PARAM.LEGS.LEGS_ARRAY(0).TERM.FIX);

                        ^^^ exception discriminat error is raised here
     --PRIMARY_FPLN_PARAM.LEGS.LEGS_ARRAY(DISCON+1).TERM := L_TERM;
      PRIMARY_FPLN_PARAM.LEGS.LEGS_ARRAY(DISCON+1).TERM := 
             (LEG_TYPE => SERVER_TYPES.TF,
              FIX => ( IDENT     => L_TERM.FIX.IDENT,
                       B_OVERFLY => L_TERM.FIX.B_OVERFLY,
                       POS       => ( LAT => L_TERM.FIX.POS.LAT,
                                      LON => L_TERM.FIX.POS.LON)));
                        ^^^ Is this OK if I correct the previous
error?
....
....

end CLEAR_DISCON;

package  SERVER_TYPES is 
......
......
   type T_FIX is
      record
         IDENT     : FMS_TYPES.T_IDENT (1 .. 7);
         B_OVERFLY : BOOLEAN;
         POS       : FMS_TYPES.T_POSITION;
      end record;

   type T_TERM (LEG_TYPE : T_LEG_TYPE := NONE) is
      record
         case LEG_TYPE is
            when DF | TF | LIF | TP =>
               FIX : T_FIX;
            when PPOS | NONE =>
               null;
         end case;
      end record;
   type T_LEG (LEG_TYPE : T_LEG_TYPE := NONE) is
      record
         MARK              : T_LEG_INDEX := 0;
         TERM              : T_TERM (LEG_TYPE);
         TURN_DIR          : FMS_TYPES.T_TURN_DIR := FMS_TYPES.NONE;
         B_DISC_AHEAD      : BOOLEAN              := FALSE;
         STATIC_PARAMETERS : T_LEG_STATIC_PARAMETERS_C;
         DISTANCE_CUMUL    : FMS_TYPES.T_DISTANCE_NM_C;
      end record;

.....
.....
end SERVER_TYPES;

package FMS_TYPES is
.....
.....
  subtype T_ANG_REL_DEG is T_DEGREE range -179.99999 .. +180.0;
  subtype T_LATITUDE is T_ANG_REL_DEG range -90.0 .. +90.0;
  subtype T_LONGITUDE is T_ANG_REL_DEG;

  type T_IDENT_INDEX is range 0 .. 30;
  type T_CHAR is
     (
      PROG,
      ....
      ....
      LOZENGE);
  type T_IDENT is array (T_IDENT_INDEX range <>) of T_ISO5_CHAR;

  type T_POSITION is record
    LAT    : T_LATITUDE;
    LON   : T_LONGITUDE;
  end record;
...
...
end FMS_TYPES;

I am using gnat compiler on AIX machine.

Hope this information is enough.

Thanks

Re: Disriminant question - Waiting desperately for solution :-(

[Gautier]

type T_TERM (LEG_TYPE : T_LEG_TYPE := NONE) is
      record
         case LEG_TYPE is
            when DF | TF | LIF | TP =>
               FIX : T_FIX;
            when PPOS | NONE =>
               null;
         end case;
      end record;
...
   L_TERM : SERVER_TYPES.T_TERM;

Well, L_TERM has the discriminant LEG_TYPE = NONE.
Then L_TERM.FIX is a nonsense. This is why...

      L_TERM := (LEG_TYPE => SERVER_TYPES.TF, 
                 FIX =>

...bombs with a "discriminant error". Fun, isn't it ?
________________________________________________________
Gautier  --  http://www.mysunrise.ch/users/gdm/gsoft.htm

NB: For a direct answer, e-mail address on the Web site!

Re: Disriminant question - Waiting desperately for solution :-(

[Grein, Christoph]

From: gautier_niouzes@hotmail.com (Gautier)
> 
> type T_TERM (LEG_TYPE : T_LEG_TYPE := NONE) is
>       record
>          case LEG_TYPE is
>             when DF | TF | LIF | TP =>
>                FIX : T_FIX;
>             when PPOS | NONE =>
>                null;
>          end case;
>       end record;
> ...
>    L_TERM : SERVER_TYPES.T_TERM;
> 
> Well, L_TERM has the discriminant LEG_TYPE = NONE.
> Then L_TERM.FIX is a nonsense. This is why...
> 
>       L_TERM := (LEG_TYPE => SERVER_TYPES.TF, 
>                  FIX =>
> 
> ...bombs with a "discriminant error". Fun, isn't it ?

No, your analysis is quite wrong. L_Tern is defined without discriminant in this 
example, so only its _default_ value is None, but it may change. So the 
assignmant to L_Tern should work.

The code snippet is too coarse to come to a conclusion why this error occurs (at 
least I didn't feel like chasing the error in this mess :-).

Re: Disriminant question - Waiting desperately for solution :-(

[Gautier]

Grein, Christoph:

> No, your analysis is quite wrong. L_Tern is defined without discriminant
> in this example, so only its _default_ value is None, but it may change.
> So the assignmant to L_Tern should work.

Thank you (and sorry for the wrong information).
I learnt again something about Ada.
In that case L_Term can change discriminant when it wants - strange!
________________________________________________________
Gautier  --  http://www.mysunrise.ch/users/gdm/gsoft.htm

NB: For a direct answer, e-mail address on the Web site!
___
PS: I couldn't resist to test - maybe the OP should start with a
simplified example and complicate it until the bug is picked...

with Ada.Text_IO; use Ada.Text_IO;

procedure Discri is

  type T_Leg_Type is (Df, Tf, Lif, Tp, Ppos, None);

  type T_Fix is new Integer;
  
  type T_Term (Leg_Type : T_Leg_Type := None) is
  record
    case Leg_Type is
      when Df | Tf | Lif | Tp =>
        Fix : T_Fix;
      when Ppos | None =>
        null;
    end case;
  end record;

  L_Term : T_Term;

begin
  Put_Line( T_Leg_Type'image(L_Term.Leg_Type) );
  L_Term := ( Leg_Type => Tf,  Fix => 0);
  Put_Line( T_Leg_Type'image(L_Term.Leg_Type) );
  L_Term := ( Leg_Type => Ppos );
  Put_Line( T_Leg_Type'image(L_Term.Leg_Type) );
  L_Term := ( Leg_Type => Df,  Fix => 0);
  Put_Line( T_Leg_Type'image(L_Term.Leg_Type) );
  Put_Line("Survived !");
end;