Re: Need some ammunition (Procedures vs. Sub-routines)

Hmm...speaking as the C.Wilt in question.... :)

Not sure I see much benefit to having the pop-up calender as a service
program instead of a program.

I suppose one could argue that the invocation would be a bit nicer

mydate = Popup_Calendar();

vs
mydate = %date();
Popup_Calendar(myDate);

It really wouldn't be difficult to make into a service program.

Charles



On Mon, Jan 6, 2014 at 2:49 PM, Booth Martin <booth@xxxxxxxxxxxx> wrote:

I wish I understood service programs better. There is one application I
believe would be an excellent service program but I do not know how to
do it.

http://martinvt.com/Code_Samples/Pop-up_Calendar/pop-up_calendar.html

It is a pop-up calendar. Its not my code but I have shown it on my web
site and I have modified it and C. Wilt fixed it up a couple of years
ago. It just seems to me that it would be a desirable service program.


On 1/6/2014 9:13 AM, Michael Schutte wrote:

I would start small. Do you do any centering of text in fields, say on a
display or printer file? If so, put the code in a service program and

use

that as an example to be able to reuse code.


On Sun, Jan 5, 2014 at 3:44 PM, TheBorg <sjl_abc@xxxxxxxxxxx> wrote:

IMHO, one big advantages of introducing subprocedures to existing

programs

is the fact that as long as the variables used in the subprocedure are
either passed in or defined locally then there is no chance that
coupling-related issues [such as inadvertently stepping on global

values]

will arise...

;-)


"James H. H. Lampert" wrote in message
news:mailman.3432.1388168538.2717.rpg400-l@xxxxxxxxxxxx...

A couple of things on the "leave well enough alone" side:

1. It's entirely possible that (perhaps without anybody realizing it) a
program might very well *depend* on side effects of a subroutine playing
around with global variables, and if one switches to local variables,
eliminating the side effects, one could break whatever depends on them.
I've seen it happen. Usually the tipoff for something dependent on a
side effect is when it works even though it looks like it shouldn't.

2. Remember: when you have OPM and ILE calling each other across
activation groups, you have an "impedance bump," but when you have ILE
actually doing ILE things (like procedure calls) in the OPM activation
group (usually only when it's set to run in CALLER, and is then called
from an OPM program), you can end up with erratic behavior. (I try to
avoid situations like that on anything I let out of the building.)

--
JHHL

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