问Python装饰器报错：AttributeError: 'function' object has no attribute 'im_class'，如何解决？

def logger(myFunc):
    def new(*args, **keyargs):
        print 'Entering %s.%s' % (myFunc.im_class.__name__, myFunc.__name__)
        return myFunc(*args, **keyargs)

    return new

class C(object):
    @logger
    def f():
        pass

C().f()

Entering C.f

AttributeError: 'function' object has no attribute 'im_class'