From: Lyle Johnson <lyle.johnson@...>
Date: 2004-08-22T01:19:52+09:00
Subject: Re: calling a swig generated function

On Sat, 21 Aug 2004 06:47:08 +0900, Michael Hale
<michael@halefamilysite.com> wrote:

> Thank you for the suggestion.  I was able to get my code to work with
> the following in my smartlib.i file:
> 
>         %apply unsigned long *OUTPUT { unsigned long *pulGap };
> 
> Now I call the function like this:
> 
>         NSCalculateGap(iMode, iSpeed, ulPacketLength, dValue, hub, slot, port)
> 
> And get back an array with the first element being the original return
> value and the second being the value of the pulGap pointer.  Like this:
> 
>         [0,1273]

OK, good!

> BTW here is the method definition from my header file:
> 
> int             DLL_EXPORT NSCalculateGap(int iMode, int iSpeed,
>                                                                                 unsigned long ulPacketLength,
>                                                                                 double dValue,
>                                                                                 unsigned long *pulGap,
>                                                                                 int iHub, int iSlot, int iPort);

Yes, I couldn't tell from your previous example (in the original post)
what kind of return value, if any, NSCalculateGap() was declared to
have -- so I guess a void return type. If you only want the wrapped
version of NSCalculateGap() to return a single value (the gap) and not
that two-element array, you might be able to do something like this:

    %extend {
        unsigned long NSCalculateGap(int iMode, int iSpeed, unsigned
long ulPacketLength, double dValue, int iHub, int iSlot, int iPort) {
            int iResult;
            unsigned long ulGap;
            iResult = NSCalculateGap(iMode, iSpeed, ulPacketLength,
dValue, &ulGap, iHub, iSlot, iPort);
            return ulGap;
        }
    }

In other words, we're introducing a helper function in the middle that
calls the "real" NSCalculateGap() function and ignores its integer
return value. If that integer return value shouldn't be ignored --
say, because it is an error code or something -- you might want to
check it first and raise an exception, or whatever makes sense for
your application.

Hope this helps,

Lyle