Re: Unconstrained arrays in nested record structures

[Warren W. Gay VE3WWG]

I believe that the only way this can work, is if
you add a record discriminant to the record, that
you can then use as the size. For example (N below):

type DTED_FILE_RECORD_TYPE(N : Positive) is record
   UHL_RECORD                      : STRING (1..1) ;
   DSI_RECORD                       : STRING (1..1) ;
   ACC_RECORD                      : STRING (1..1) ;
   DTED_DATA_RECORD          : RECORD_ARRAY_TYPE_1 ( 1 .. N ) ;
end record ;

If you plan to use Ada.Direct_IO, then I think you'll
also need to have a default value for the discrimant
N as well.

BTW, you posted your message in HTML, which may not
be what you really want on an email list/newsgroup.

Warren.

Prichard, Jayson wrote:
> I am trying to design a nested record structure with each record having 
> an unconstrained array.  Can anyone tell me if the following is possible 
> in Ada/GNAT?  How should this structure be accessed?
>
>  type RECORD_ARRAY_TYPE_2  is array ( INTEGER range <> )
>     of INTEGER ;
>
>
>  type DTED_DATA_RECORD_TYPE is record
>     DDR_RECOGNITION                     : STRING (1..1) ;
>     DDR_DATA_BLOCK_COUNT         : STRING (1..1) ;
>     DDR_LONGITUDE_COUNT            : STRING (1..1) ;
>     DDR_LATITUDE_COUNT               : STRING (1..1) ;
>     DTED_ELEVATION_RECORD        : RECORD_ARRAY_TYPE_2 ( 1 .. 
> NUMBER_OF_ELEVATION_POSTS_PER_CELL ) ;
>     DDR_CHECKSUM                         : STRING (1..1) ;
>  end record ;
>
>  type RECORD_ARRAY_TYPE_1  is array ( INTEGER range <> )
>     of DTED_DATA_RECORD_TYPE ;
>
>  type DTED_FILE_RECORD_TYPE is record
>     UHL_RECORD                      : STRING (1..1) ;
>     DSI_RECORD                       : STRING (1..1) ;
>     ACC_RECORD                      : STRING (1..1) ;
>     DTED_DATA_RECORD          : RECORD_ARRAY_TYPE_1 ( 1 .. 
> NUMBER_OF_RECORDS_PER_CELL ) ;
>  end record ;
>
>    DTED_FILE_RECORD : DTED_FILE_RECORD_TYPE  ;
>
>    DTED_DATA_FILE : DIRECT_IO.FILE_TYPE ;
>
>  package DIRECT_IO is new ADA.DIRECT_IO ( DTED_FILE_RECORD_TYPE ) ;
>
>    use DIRECT_IO ;