Re: Subroutines vs Subprocedures was RE: Indicators

On Tue, 24 Aug 2004 17:01:07 +0000, Joel Cochran <jrc@xxxxxxxxxx> wrote:
> 
> Encapsulation is a great idea when applied properly.  And this article
> should prove I think this can be done in RPG:
> 
> http://www.midrangeserver.com/fhg/fhg072104-story01.html

Cool link, great article.

> However, there is nothing wrong with internal sub-procedures accessing
> global program variables.  You are trying to apply a C++ OO standard to
> a procedural language, and frankly it just doesn't follow.  Remember we
> are talking about sub-procs WITHIN a program here, not in another
> *MODULE.  As such, you may find that you are required to use global
> variables.

I concede about the global variables, although I do maintain that it
should be avoided.  The SQL issue (you cite below) is in my view an
implementation problem.

My point was that SubProcedures were created to allow for
encapsulation and other OO concepts to be implemented more easily
using RPG, and also in a manner consistent with other languages. 
There is no huge benefit to using them in place of EXSR other than to
become more familiar.

> Take embedded SQL for example: try putting an SQL statement in a
> sub-procedure that uses a local variable.  It just isn't happening.  And
> as others pointed out, the fields from a file defined in an 'F' spec are
> global without question.  I like to "encapsulate" my screen access for
> standard file maintenance in sub-procedures, but this means the screen
> variables (and the file variables) are global.

Makes sense, but in that case there is little difference between a
SubProcedure and a SR.

I think that winds around to where I was going.  There is very little
functional difference between a SR and an internal SubProcedure.   The
real value of SubProcedures is that they allow for changing the DESIGN
of the applications to use encapsulation, OO concepts, and improving
reusability and modularity.

Back to the very start here . . . if the guy has designed his
application already, is writing code, and is wrestling with the
decision of whether to use SubProcedures or EXSR, he is too late and
at that point it really doesn't matter.

> > How often have you had to bend over backwards to re-use a subroutine
> > because of all of the "setup" work required.  If the SR were a
> > properly isolated SubProcedure, the re-use is much easier.
> 
> This is, in fact, the point of sub-procs, but not what this discussion
> was about.

I guess I was trying to take it there . . . 

-- 
Tom Jedrzejewicz
tomjedrz@xxxxxxxxx