Re: Benefits of Sub-procedures

["Buck" <buck.calabro@xxxxxxxxxxxx>]

> So why reinvent the wheel or rewrite a good
> working, existing programme and tranform it
> to a procedure? Perhaps the only adjusment
> required is prototyping the call.

Carel, you said it better than I did.  I think the dispute is over what
'good' means.  In my case, at an earlier job I had an application that was
made of small server programs.  In order for it to run fast enough, we had
to use shared ODP's and return without LR.  I would NOT advise changing that
application to use procedures today because it DOES work well and it DOES
run fast.

> I worked in a software shop, where the reply to
> a request for newer coding tecniques was: "Our
> clients are not interested how the programmes
> are coded, only that those programmes work
> as intended and without errors."

We certainly have that attitude.  Which is while RPG IV and ILE have been
helpful here.

>I think a lot of (software) shops have that attitude,
>as ILE requires a (complete) redesign of application
>development and the existing code (the legacy)
>is not that easily transformed.

I think you are partly correct.  A full ILE application with shared
resources (multiple activation groups) requires careful design.  But it is
not a difficult chore to add a sub-procedure to an existing program (even
using a service program to hold it.)  Let me share an example of how this
has personally helped me.

I had a large, old-fashioned LARGE program that was converted to RPG IV (to
use the larger arrays!), but did not use sub-procedures.  I had to add a
section of code to verify whether a telephone number was in the local
calling area or not.  I already had a subroutine in another program that did
almost the same thing, but the field names were all wrong.  I had two
choices: make the subroutine into a program and call it, or make it into a
sub-procedure.  By making it a sub-procedure, I was able to make this change
to the main program.

>From this:
If test1 and test2 and test3

to this:
if test1 and test2 and test3 and localCall(telephoneNumber)

Or, I could have made a temporary variable and done this:
call localcall
parm telephoneNumber
parm isLocal
if test1 and test2 and test3 and isLocal

Either way works, but the sub-procedure is a little more flexible, because I
don't need another variable.  The point is that I was very comfortable
making this change to the large program, because I _knew_ that the change I
made would not have any repercussions beyond the one test.  This means I can
make changes faster than having to analyse all possible name collisions, and
that my changes are more reliable.  So that is why I use sub-procedures in
RPG IV even though I am not doing full ILE.
Groetjes!  :-)
  --buck