RE: Prototypes and parameters

["Reeve Fritchman" <reeve@xxxxxxxxxx>]

Thanks to those who answered; I still haven't come up with an elegant
solution.  Unfortunately, it appears the best solution is a subprocedure,
although this (admittedly not every pretty) works too:

Daar007           pr                  extpgm('AAR007')
D                               10    const
D                               10

C                   callp     aar007('TERMS':q_alpha_10)
C                   eval      terms_code =   q_alpha_10

The problem is in the calling program: it thinks the 2nd parameter is always
10 bytes but it's not.  It appears the calling program takes the full 10
bytes returned (because that's how it's defined) and slaps it into the
starting memory address of the 2nd parameter.  The fact than P2 is only
three bytes is of no concern to the compiler; the extra seven bytes smack
whatever field is next to it in memory (which usually is numeric...sigh...).

It seems as though what I really want to do (with thanks to B. Cozzi) is set
the size of the second parameter (which has the returned data) in the
calling program; to do this, I'd have to define parameter 2 as VARYING in
both the procedure interface and prototype.  Then I'd be able to set the
size of P2 to 3 (for example) and the calling program would know to move
three bytes from the parameter list control block (?) into my 3-byte
variable.

Unfortunately, the compiler doesn't like the idea of a fixed-length field
passed through a VARYING parameter, and I concur with S. Klement, who
observed observation that having all calling programs pass a VARYING field
is not ideal.  I don't think OPTIONS(*VARSIZE) offers anything.

In thinking about this a little more, I could probably write a subprocedure
wrapper for the called program; this would allow me to use it as a function,
i.e.

     C                   eval      terms_code = wrapper_aar007('FHTRM')

...and this code is self-documenting.  I need to get it into a service
program anyway...

Well, time to head to the dog pound.  Guth-Pup (www.ltl400.com) was two
yesterday and he's having his girlfriends over tonight for chicken liver and
cream cheese birthday cake.

Regards,
Reeve