Re: Call back procedures

[Scott Klement <rpg400-l@xxxxxxxxxxxxxxxx>]

I've written massive amounts of code using call-backs.  They are a good 
way to write tools intended for programmers, allowing those programmers 
to insert their own code at key points in the process.  Making things 
much more flexible (usually at the cost of complexity)

The only real gotcha that I know of with callbacks themselves is that 
you end up defining the prototype for the procedure twice, and there's 
no system-provided tool that verifies that the prototypes match.  Thus, 
it's relatively easy to have parameter mismatches (much like the old 
CALL/PARM/PLIST opcodes -- you eschew many of the advantages of prototypes)

Other than that... it's hard to find a "gotcha".  I mean, callbacks are 
plumbing.  They are a way to call a routine.    Sometimes they are the 
right tool for the job, and sometimes they are not.  But without any 
context, it's hard to list "gotchas" or "should-a/could-a".

So... what do you plan to do with your callback?


Rick.Chevalier@xxxxxxxxxxxxxxx wrote:
> I think we may have encountered a situation in our shop where call
> back procedures would be helpful.  I recently read an article by Joe
> Pluta describing the concept and it makes sense to me.  My question
> is does anyone have real world experience with call back procedures
> that would be willing to share any gotcha's or I wish I had done this
> experiences?
>
> I would like to find out about them now while we are still designing rather than later.