Re: Keyword "null" Question

[Peter Amey <peter.amey@praxis-cs.co.uk>]

Michael Bustillo wrote:
> 
> While reviewing the Ada LRM, it makes note that the Ada keyword "null"
> does nothing except pass to the next statement.  This seems intuitive
> enough, however...
> 
> I'm currently attempting to reverse engineer some code so that it can be
> converted to another language, and I've run across the following:
> 
>     if SOME_EVENT_TOOK_PLACE then
>         null;
>     end if;
> 
> This statement is simply standing alone by itself, not part of any
> "case-like" structure or anything sneaky.  I guess my question is when
> it says "...it does nothing..." does it actually mean that it is putting
> a NO OP there?  Because then this would actually be doing something,
> most likely a timing issue, and that's what I need to know.
> 
> I appreciate your time, and thanks.

I would have thought that this is most likely a hook for some planned
future development.  I have written code that cased or looped over an
enumeration type with a single element for example where extension
seemed likely.  I am confident that the source statements would not
generate any object code  given any half-decent optimization.

Peter