Re: Keyword "null" Question

["Warren W. Gay VE3WWG" <ve3wwg@cogeco.ca>]

Peter Amey wrote:
> 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

One other possibility might be that it was pre-processed by some
tool that precompiled out some optional code (something like gnatprep).
Or more likely, the code that used to be there was commented out and
a null was stuck in there to make it compile ;-)

-- 
Warren W. Gay VE3WWG
http://home.cogeco.ca/~ve3wwg