Hello,
... the free format op codes for file i/o, that the compiler does not
seem to be testing the length of the fields ...
Yes, that is expected/documented behavior. Here's a link to the ILE RPG
Reference manual:
http://tinyurl.com/lpcxxd
here's what the documentation says (this is copy/paste from the link
cited above):
For free-form calculations, a search argument may be:
1. A single field name
2. A klist name
3. A list of values, such as "(a:b:c+2)". Each part of the
composite key may be any expression. Data types must match the
corresponding key field, but lengths and data format do not
have to match.
4. %KDS(ds{:num})
Note that option #3 (which is the one you're referring to) states that
data types must match, but lengths and format do not have to match. I
find that behavior to be very helpful.
We have files where the lengths aren't consistent (GL number is 5,0 in
one file, 6,0 in another file. I don't have to move the number to a
temp field, I can just chain with it!)
chain (inputGL) GLMAST;
In this example, inputGL is 5,0, but the key to GLMAST is 6,0. No need
to copy to a temp variable.
You can use any expression for these key fields -- so it works just like
EVAL works, which I find to be very intuitive. When you assign one
variable to another with EVAL, the data types of the variables don't
have to match. (You can assign a 6,0 field to a 5,0 field, as long as
the number would fit in a 5,0 field...)
Expressions also mean you can do some manipulation. For example, I can
convert a date field from one format to another right on the keylist.
setll (%dec(%date(inputField:*USA):*ISO)) Calendar;
The above code converts a field from MMDDYYYY format to YYYYMMDD right
on the keylist. Saves me having to code a temporary field.
Furthermore, we have some inventory files where a "location" is
represented by a warehouse number (1A) and a location (7A). And we have
some where it's one 8A field. No problem! I can do this:
chain (WHSE + LOCATION) MyFile;
In this case, the two fields (WHSE and LOCATION) get concatenated, and
then the output is used as the first key to MyFile. Again, saves me
effort of coding a temp field.
If you want to guarantee that your field sizes match, you can use %KDS
or KLIST to get that behavior. So you can do it either way, best of
both worlds. But personally I like having the flexibility of expressions.
midrange.com
