Re: Omissible vs Optional parms (was How to determine if device is 27x132?)

>Date: Thu, 10 Feb 2000 01:09:56 -0500
>From: dhandy@isgroup.net (Douglas Handy)
> ...
>I use a prototype like this, where ApiErrorDS is my standard error DS:
>
>     D QryModSup       PR             1    ExtProc( 'QsnQryModSup' )
>     D  DspMode                       1    Const
>     D  Handle                       10I 0 Options( *NoPass )
>     D  ErrorDS                            Options( *NoPass )
>     D                                     Like( ApiErrorDS )
>
>Note that the last two parameters are optional, and you can just
>
>     C                   Eval      Is27x132OK = QryModSup( '4' )
> ...

Doug, those parameters are listed as "omissible", not "optional".
They should have options(*omit), not options(*nopass).  You can
get away with not passing them 999,999 times out of a million, but
on the millionth time a valid pointer will be on the stack where the
API is checking for it, and it will write data to "some" storage,
somewhere.

In general, optional parameters are only used for APIs that are
*PGM calls.  Bound APIs don't normally have any way of detecting
the number of parameters passed.

Barbara Morris


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