Scope of variables and subprocedures.

[bmorris@xxxxxxxxxx]

>Date: Sat, 11 Dec 1999 20:56:26 -0700
>From: Alan Campin <Alan.Campin@CaseLogic.com>
>
>The problem concerns the scope of variables. In language like "C" or
"Java"
>or "Pascal", I can do the following:
> ... example of nested subprocedures
> ...
> To get around this, I have three choices that I can see.
>
> 1. Pass every variable needed by anyone of the procedures to each
> procedure.
> ...
> 2. Make any variable needed by different subprocedures global.
> ...
> 3. Use subroutines.
> ...

Alan, you are right that you can do this in Pascal, but neither C nor Java
supports nested procedures.  It's true that you can sort of do this in Java
with nested classes. C and Java do allow you to have variables scoped to a
block within a procedure, but the block isn't callable from within the
procedure.

I realize that C's deficiency doesn't mean RPG isn't deficient.  I agree
that nested subprocedures would be nice to have, but I can't say that it
will happen in my "lifetime" since there are other things that RPG needs
that are more important (in my opinion anyway).

One solution that you haven't mentioned is moving the procedure that
requires nested subprocedures into another module, and making those
variables global within that module, but not visible outside the module.
(Of course, this solution only works if the procedures don't need other
global variables.)

Barbara Morris, IBM Toronto Lab, RPG Compiler Development


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