Re: Correct use of STATIC variables

[Vern Hamberg <vhamberg@xxxxxxxxxxx>]

David

I think the point of STATIC variables is, you DON'T initialize them 
between program calls. At least, not according to this description from 
the RPG Reference on static variables. I mean, how do you initialize 
something that is not visible outside of its context, such as a procedure?

=================================================================
Local definitions use automatic storage. *Automatic storage* is storage 
that exists only for the duration of the call to the procedure. 
Variables in automatic storage do not save their values across calls.
Global definitions, on the other hand, use static storage. *Static 
storage* is storage that has a constant location in memory for all calls 
of a program or procedure. It keeps its value across calls.
Specify the STATIC keyword to indicate that a local field definition use 
static storage, in which case it will keep its value on each call to the 
procedure. If the keyword STATIC is specified, the item will be 
initialized at module initialization time.
Static storage in the main procedure is subject to the RPG cycle, and so 
the value changes on the next call if LR was on at the end of the last 
call. However, local static variables will not get reinitialized because 
of LR in the main procedure.
=================================================================

My first question is, what are you trying to accomplish when you use the 
STATIC keyword? I don't find many uses for it, to tell the truth. There 
is the idea of thread-local storage - this is a separate copy of the 
variables for a procedure that is called in different threads of a job. 
If you are using it for performance reasons, to avoid initializing the 
storage on each call, that is a waste of development time, in most 
cases. Someone once said that the 3 rules of optimization are "Don't! 
Don't! Don't!" At least not down to the most minute level.

So it'd help to know why it is being used - even things like counters 
can be handled with parameters instead of static variables.

I believe the scratchpad of SQL functions can be static storage - but 
does not need to be, apparently. Just looked it up!!

HTH
Vern

David FOXWELL wrote:
> What is the normal manner to initialize such variables between program calls? Without using activation group *NEW. Currently, it seems we are relying on a CLP that issues a RCLRSC.
>
> Thanks.
>
>