Re: linking tool to use a framework : obj_send_msg error

[David Chisnall]

On 13 Apr 2009, at 20:49, Thomas Kupper wrote:

> > There is probably some 'optimisation' in the framework calling the  
> > Apple runtime message send function directly (the quotes because  
> > anything doing I/O like this is likely to gain an imperceptible  
> > performance increase from calling the runtime functions directly  
> > rather than using -methodForSelector:). Try grepping the source  
> > code for objc_msgSend() and, in files that contain it, add this  
> > macro:
> >
> > #define objc_msgSend(theReceiver, theSelector, ...) \
> > objc_msg_lookup(theReceiver, theSelector)(theReceiver, theSelector,  
> > ## __VA_LIST__)
>
>
> Perfect! That's exactly what causes the error. In one file there are  
> three calls to objc_msgSend. Now I tried to define the macro you  
> mentioned. Unfortunately the # __VA_LIST__ part is not recognized  
> and Google wasn't any help, and neither was a find ... -exec  
> fgrep ....

Sounds like you have your compiler set to use some archaic dialect of  
C.  Add -std=c99 to your CFLAGS.

> On the other hand, if there are only three calls to objc_msgSend in  
> only one file I could maybe just replace these three calls. But the  
> objc_msg_lookup calls seems to be quite unusal.

You can do that too, just expand the macro, so:

objc_msgSend(obj, sel, args);

becomes:

objc_msg_lookup(obj, sel)(obj, sel, args);

(objc_msg_lookup() returns a pointer to the function that you call.   
objc_msgSend() does the lookup and the call as a single operation in  
the Mac runtime).

David