Re: Program design to minimize record locks

OK! So the compile works but the I am not getting what I expected (maybe this IS harder than I thought).

Based on the prior posts from Booth, I thought I understood that the D spec for the data structure would hold a copy of the data read from the file "automagically". He said "The FileNameDS does in fact always have the most recently read data values, whether from the original read(n), the screen exfmt, or the locking read." So either I misunderstood or I am doing something wrong (that wouldn't surprise me).

Booth suggested the following:

D FileNameDS ds extname(Filename)
D OrigData s like(FileNameDS)
D NewData s like(FileNameDS)



This wouldn't compile until I changed the extname to likerec (and I had to add an "e" for externally described). I assumed that a read on Filename would automatically populate FileNameDS but that isn't the case. A read on Filename puts no data into FileNameDS. So I misunderstood or did it wrong.

Pete


Pete Helgren wrote:

Got it! I appreciate the clarification. It compiles now.
Thanks,

Pete


Scott Klement wrote:

Pete Helgren wrote:

A little wrinkle here:
The compiler seems unhappy with the fact that I have the RENAME

File spec has:

FPMYFILE UF A E K DISK RENAME(FMYFILE:FILE01)
DFileNameDS E ds extname(FILE01)

Did you mean to use LIKEREC?

A data structure defined with EXTNAME has absolutely no relationship with the F-spec. Instead, you tell EXTNAME the external name of a file, and it looks for it on disk to get the fields. Since the argument for EXTNAME is a FILE NAME (not a record format name) and it's looking directly at the file (not at the F-spec) I wonder if you really meant to use LIKEREC?

LIKEREC defines a structure to be like a record format that you've defined on an F-spec. So you could say

DFileNameDs ds likerec(FILE01:*input)

And that would work, because it's argument is the RECORD FORMAT NAME (which is what you renamed) and it's looking at your F-spec rather than directly looking at the file.