Re: Call by reference

[Jim Essinger <esinger@xxxxxxxx>]

Leif,

Activation groups (AG) allow me to protect my data from other programs
(and/or programmers).  If I keep the file I/O ILE Modules running in a
separate AG, other programs can't get at the data because they can't cross
the AG boundary.  It really is not that complicated.  Mostly you have to be
careful of the activation group name.  I have some programs that calculate
interest on loans, and I don't want any other program messing with that
calculation.  I run the program (or module) in a separate, named AG (or
better yet in a "NEW" AG), and other programs can't mess with the calculation.

Most of the time this kind of security is not needed, however, I still like
to use "external" data structures and files where possible.  It allows me
to write a file I/O  or interest calculation program once, and use it many
times, and not have to code massive linkage sections in my programs.  If
both programs already know about the data, I can just use it. I can also
use copy books (could with Linkage section too) to define the common data
structures, and if they change, then I can change it in one place, and
recompile all programs that use that code.

If the module is being called 500,000 times each night, the performance
gain (ILE over OPM) can be significant.


It's late here, and I don't know if I'm making any sense.  I think I'll
quit while I'm ahead!  ... at least I think I'm ahead. ...

At 04:03 PM 8/23/2002 -0500, you wrote:
>From: jim essinger <esinger@fmtc.com>
> > The answer is - it depends.  IF you are using ILE COBOL (RPG does not have
> > external sharing of files and data structures) and IF they are both called
> > from the same job, and IF they are in the same activation group, then
> > anything that ProgramB changes, ProgramA will see.
> >
>
>and then why not simply pass it as a normal parameter
>and avoid all these ifs, buts, and maybes?

Jim Essinger
Senior Programmer/Analyst
Student Loan Fund of Idaho
PO Box 730
Fruitland, ID  83619
esinger@fmtc.com