What happens when an objective_C program sends a message to nil?

The default behavior of objective_C, using gcc, is to do nothing...no warning, no crash, nothing. This can make it hard to find bugs.

To override this behavior, all you have to do is include a function like the following in your program:

///////////////////////////////////////////////////////////////////////
// nil_method
// include this if you want this message printed whenever
// a message was sent to nil.

//#ifdef THIS
id nil_method (id receiver, SEL op, ...)
{
    fprintf(stderr,"The message `%s' was sent to nil\n", sel_get_name (op));
    // a standard swarm approach:
    //raiseEvent (WarningMessage, "`%s' was sent to nil\n", sel_get_name (op));
    return nil;
}
//#endif