Nested Calls

[Jose Lerebours]

On 05/02/2018 07:27 PM, Fairlight via Filepro-list wrote:
> On Wed, May 02, 2018 at 07:06:49PM -0400, Jose Lerebours via Filepro-list thus spoke:
>> Again, I can see calling one or two tables but the use of "nested"
>> and wonder about how deep you can go gives me pause and wonder why
>> one would need more than two or three ... I have written very large
>> and very complex filePro application and never needed more than one,
>> perhaps because I adopted to the handicap back then.
> Let's say you have a routine which deals with latitude and longitude
> conversion.  You make a prc.latlonconv to do your conversion tasks.
>
> Now let's say you have always needed this from input processing.  That's
> fine.
>
> One day, you write a new routine which is called from input.  Let's say
> it's prc.newtask.  Unfortunately for you, you need "newtask" to actually do
> some "latlonconv" work.  So simply CALL it from inside "newtask".  Oh
> -wait-!  You can't!  Why?  Because you've already CALLed "newtask" from
> input, so you're one level deep already.  Prior to 5.6, that one level deep
> is all you got.
>
> To do what you need to do, you need...wait for it...  NESTED CALLS.
>
> As we have said already, nested calls let you use one universal chunk of
> code -from anywhere-.  This means from zero levels deep, or 20 levels deep.
> Doesn't matter, it just works.
>
> If you have trouble wrapping your mind around the lat/lon example (just
> something I pulled out of thin air), imagine something more practical like
> a custom logging routine.  You have a routine which will append a log
> line to a centralised file, which also maintains the file as a rolling
> ring buffer, so your disk doesn't fill up.  All you need to do is set a
> variable and call your routine, and it handles the hard work of logging
> -and- keeping your size constraint constant.  You -could- use it to debug
> your code product-wide with one unified interface, if you have nested
> calls.  Without those, you can't do that without replicating the majority
> of the logging code in every table where you want to use it.  Not exactly
> plug-and-play modular, in that case.
>
> mark->

Mark, at the OS or Sys Admin level I tip my hat to you ... as a 
developer, well, you wont get same respect from me.

Having had experience writing OO and Procedural code, I fully understand 
the benefits of "nested calls", I still believe that there should be 
little to need to nest so deep that you need to concern yourself with 
"how deep can I go?".

News watching time ... I'm out!