Re: Test for constant (or "in parameter" in procedure)

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 09/02/2017 13:46, reinkor wrote:
> OK, I here try to communicate my intention via this simple example:
>
> i : Constant Integer := 5; -- all OK so far (but someone could
>                                change this to a variable)
>
> begin
>
> .... some code ...
>
> if "i is not constant (cannot change value)" then
>    Some_error_handling;
> end if;

i cannot change its value all its life time. This is regardless how its 
initial value was obtained.

> (or alternatively error message/warning at compilation)

Maybe we could help better if you tell us what the original problem is.

If you consider this:

loop
    declare
       I : constant Integer := Read_From_File;
    begin
       ...
    end;
end loop;

It would be meaningless to ask if I changes its value. There are many 
I's all unrelated to each other. If you want to relate them, you must 
move the declaration of I to the least common scope, e.g. like this:

declare
    I : Integer; -- Now it is only one I for each iteration
begin
    loop
       I := Read_From_File;
       ...
    end loop;
end;

You can immediately see that I is not a constant. And you could not make 
it constant.

As it was said, it is either constant (immutable) or not (mutable). Your 
very question is meaningless.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de