覆盖的方法不包含自我？(Overwritten Methods don't contain self?)

这是我刚刚在我的机器上播放的一个例子：

$ python Python 2.7.4 (default, Apr 19 2013, 18:28:01) [GCC 4.7.3] on linux2 Type "help", "copyright", "credits" or "license" for more information. # just a test class >>> class A(object): ... def hi(self): ... print("hi") ... >>> a = A() >>> a.hi() hi >>> def hello(self): ... print("hello") ... >>> >>> hello(None) hello >>> >>> >>> >>> a.hi = hello # now I would expect for hi to work the same way as before # and it just prints hello instead of hi. >>> a.hi() Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: hello() takes exactly 1 argument (0 given) >>> >>> def hello(): ... print("hello") ... # but instead this one works, which doesn't contain any # reference to self >>> a.hi = hello >>> a.hi() hello >>> >>> >>> >>> >>> a.hello = hello >>> a.hello() hello

这里发生了什么？当它用作方法时，为什么函数不会获得参数self？我需要做些什么来获得对自我的引用？

Here is an example I just played through on my machine:

$ python Python 2.7.4 (default, Apr 19 2013, 18:28:01) [GCC 4.7.3] on linux2 Type "help", "copyright", "credits" or "license" for more information. # just a test class >>> class A(object): ... def hi(self): ... print("hi") ... >>> a = A() >>> a.hi() hi >>> def hello(self): ... print("hello") ... >>> >>> hello(None) hello >>> >>> >>> >>> a.hi = hello # now I would expect for hi to work the same way as before # and it just prints hello instead of hi. >>> a.hi() Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: hello() takes exactly 1 argument (0 given) >>> >>> def hello(): ... print("hello") ... # but instead this one works, which doesn't contain any # reference to self >>> a.hi = hello >>> a.hi() hello >>> >>> >>> >>> >>> a.hello = hello >>> a.hello() hello

What is happening here? Why doesn't the function get the parameter self, when it is used as a method? What would I need to do, to get a reference to self inside it?