import kaa
import _weakref

def logerror(w, error):
    print 'unhandled error:', error
    
class Foo(object):
    def __init__(self):
        self._weakref = None

    def throw(self):
        self._weakref = _weakref.ref(self, kaa.Callback(logerror, 'error message'))

    def handle(self):
        self._weakref = None
        
print 'start'
f = Foo()
f.throw()
# comment in/out the next line to see the difference
f.handle()
del f
print 'done'