Re: record question

[whraven@usenet-access.com (Richard Pinkall-Pollei)]

>assume that I have a record like the one below. I can assign aggregates
>in the case that I have subcomponents, but how do I assign if I don't
>have?
>
> [code example moved to end of message for reference]

The record type you are using is "mutable", since it has a default
discriminant.  Thus, you can change the discriminant, but only if you
provide a complete record or aggregate in the assignment.  Thus, you
would have to use "y := ( i => 99 ) ;" since it assigns a complete
aggregate (since "i" is the only component for this discriminant
value).  You cannot use the "y.i" form, since that would technically
only assign a single component, even though the record has only one
component.

I ran your code fragment through the GNAT 3.13p compiler, just to see
if it was smart enough to realize that "y.i" was, in fact, the only
record component.  The error message resulting from the "y.i"
assignment states that the left hand of the assignment must be a
variable.  I would say that's not the real problem, but I'm not sure
why GNAT flags it this way.

>procedure RT is
>  type x (i : Integer := 0) is
>    record
>      case i is
>        when 0 => null;
>        when 1..10 => s : STRING (1..10);
>        when others => null;
>      end case;
>    end record;
>    
>  y : x;
>begin
>  y := (1, "ABC       ");  -- this is OK
>  
>  y := (99);   -- but, how do that ?
>
>  y.i := 99;   -- do not work either, so how assign a value different to
>1..10 ?
>end RT;


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