Re: Porting from Modula-2 to Ada

[Jeffrey Carter <jrcarter@acm.org>]

Lutz Donnerhacke wrote:
> generic
>   type T(<>) is limited private;
> procedure Xxx (data : T);
> 
> procedure Xxx (data : T) is
>   use System.Storage_Elements;
>   raw : Storage_Array (Storage_Offset'First ..
>         Storage_Offset'First + (data'Size + Storage_Unit - 1) / Storage_Unit);
>   pragma Import (Ada, raw);
>   for raw'Address use data'Address;
> begin
>   ...

System.Storage_Elements.Storage_Array is the best way to deal with 
untyped storage in Ada. This example is almost right; it seems to 
allocate one more Storage_Element than it should. A better way to 
achieve the same thing would be

Raw : Storage_Array (1 .. Data'Max_Size_In_Storage_Elements);

which avoids such off-by-one errors.

-- 
Jeff Carter
"Now look, Col. Batguano, if that really is your name."
Dr. Strangelove