weakobj.py 文件源码

def _make_callback(obj, callback):
    # Wraps the given callback function for use with weakref.ref callbacks,
    # ensuring that a reference cycle is not created between the wrapper object
    # and the weak reference.
    if callback is not None:
        self_ref = weakref.ref(obj)
        def delref(ref):
            callback(self_ref())
        return delref
    else:
        return None