RE: subroutines are bug factories was: Classic Traps -- I need yourinput!

That is an important point. I would suggest the best practice to be using a locally defined data
structure to record level I/O.

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Barbara Morris
Sent: Monday, March 31, 2008 3:33 PM
To: rpg400-l@xxxxxxxxxxxx
Subject: Re: subroutines are bug factories was: Classic Traps -- I need yourinput!

Murphy, Mark wrote:

No, local variables do not make the code more bug prone because they are only applicable to the
subprocedure, and since a subprocedure only does a single thing, it isn't all that big. Therefore,

a

subprocedure isn't terribly hard to read and understand. And since a subprocedure only does a

single

thing, and has no side-effects, it is easy to reuse wherever it is needed; just like a BIF.

One gotcha with local variables: If you have procedure in a module with
a global file, and the procedure does a READ or WRITE without a result
data structure, then the I/O operation will use the global fields on the
I or O specs. If you have defined local fields with the same names as
the global fields, your procedure won't be able to see the values of the
changed fields from the READ, or the unchanged global fields' values
will get written out to the file.

Moral: If you want to do I/O to a global file in a procedure, don't
define local variables with the same names as fields that appear on any
I or O specs (in the compile listing).