RE: visibility of file fields

[Scott Mildenberger <Smildenber@xxxxxxxxxxxx>]

Joel,

When you have a local and global field (all file fields are global) with the
same name, they are in fact two different fields.  And within the
subprocedure the local field will 'hide' the global one which means you
cannot access the global field within the subprocedure.

Scott Mildenberger

> -----Original Message-----
> From: Joel Fritz [mailto:JFritz@sharperimage.com]
> Sent: Wednesday, March 27, 2002 2:54 PM
> To: MIDRANGE-L@midrange. com (E-mail)
> Subject: visibility of file fields
>
>
> This isn't something that is a big problem for me, but it was
> puzzling.  I
> have a service program with a bunch of subprocedures that
> look things up in
> files.  I wanted to use a data structure in one of the
> subprocedures to
> concatenate a couple of file fields for easy coding of
> comparisons.  It
> doesn't work.  The compiler flags the field names in the data
> structure
> (which use the names of the file fields) as undefined.  I'm
> assuming that
> it's a local variable deal, because the cross reference shows
> all uses of
> the field names related to the fields in the data structure
> rather than the
> file.  Besides that, if I give the fields in the data
> structure data types
> and lengths, the program will compile, but not use the file fields.
>
> In retrospect it makes sense, although it's making me a
> little confused
> about local and global variables.  This seems to mean that if
> you use the
> name of a global variable as a data structure subfield in a
> subprocedure,
> the compiler sees it as a local variable.  OTOH, if the name
> doesn't appear
> on a D spec, you can use it as a global.  If the data
> structure were defined
> as a global variable, it would work--I tried it.
>
> Here's a very schematic look a the code:
>
>  h nomain
>  Ffile1     if   e           k disk
>
>
>   P subprocedure    B                   EXPORT
>   D subprocedure    PI             5u 0
>   D parm1                         25A   CONST
>
>   D datastruct      ds
>   D  file1fld1
>   D  file1fld2
>   ................
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