RE: Load all subfile

> From: Booth Martin
>
> Thank you Joe.  That was pleasing to read.

Hey, you deserved it.


> Before I go all teary-eyed here, I originally agreed with you.  In a
> desrperate attempt to write lots of subfiles fast I stumbled on
> the load-all
> and discovered in most of the cases the load-all worked and could be in
> production in under an hour from the time the user specified the layout.

I understand.  I actually use the load-all technique in circumstances where
I expect my subfile to be no more than a couple of hundred records max.  But
I came from SSA, and even our master file maintenance programs could be more
records than would fit in a subfile, so we by necessity had to use page at a
time.

What I've done since then is develop a flexible skeleton.  I use a
state-driven machine, which easily allows movement from one screen to
another and one function to another.  I've got two variables, one for the
screen, and one for the function.  The function has values like LOAD,
DISPLAY and PROCESS.  Each function has its own subroutine, and the
subroutines are pretty standard.  They're smart enough to handle checking
for more records, saving the state of the cursor and things like that.

A nice compromise is the extendable subfile, where you load the first page,
then load additional pages as the user pages down.  Paging up and down
through already loaded records is taken care of by the operating system.
But this approach still has the limitation of 9999 records.

The biggest drawback to static subfiles has been pointed out by others: they
don't handle data changes well.  You either show old data, or you force a
reload based on events.  With triggers, the latter is a little easier these
days, but there can still be problems.

The hardest part to handle with page at a time is handling enterable fields.
For PDM-like displays, you need to have your own internal arrays to hold the
enterable fields as the user pages through the subfile.  It's not
particularly difficult, but it is time-consuming.  Here, too, a skeleton
program helps.

Joe