ABAP_to_the_Future

B
Making Programs Flexible
target program, but either way the two programs are now different, and copying
over any updates now becomes fraught with danger.
왘 When the same customizing value mean s different things in different SAP
systems
Once again, you might copy your program from the master system to a subsidiary
system—and this time the target system does have the value ZX23, but it
means something totally different. This is a worse problem, because your program
will react to the value but do something unexpected. You can do the same
fix when customizing values are different in different systems, but with the
same problem.
As an aside, this approach also makes code hard to read. After all, what is a ZX23
anyway? You tend to have a limited numb er of characters in customizing values
(sometimes only one character), so it’s hard to make those values meaningful.
Other programmers will look at the code and struggle to understand what’s going
on.
Once my company sold a business unit to another company, and because I had
written most of the software I was hired out for a week to help the new company
modify my programs for use in their system. It turned out that one of the major
programs only had about five lines that needed changing, because I had hardcoded
some customizing values of delivery types and the like, and it was just a
question of replacing those values with the new company’s equivalent values,
and that was that. There are three ways I could have reacted to this:
왘 I could have thought, “Oh no, if I had hard-coded much more and written the
program in an inflexible way, we could have had a lot more consulting hours
out of this.”
왘 I could have said, “Whoopee! How good is this! I wrote this program to be so
portable that it needs minimal changes when transported into to a totally foreign
SAP system. Hang out the flags!”
왘 What I actually thought was, “Hang on; if I can write a program that’s 95% portable,
then why not one that’s 100% portable? After all, that’s what SAP does.
Programs like SAPMV45A (VA01) work in any company.”
When looking through custom programs, it’s often amazing how many assumptions
are made; programmers take things for granted because they are always true
in their company.
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