小编vii*_*iis的帖子

考虑以下课程:

class Foo(object):
    def bar(self):
        print(self)

在Python 2(2.7.13)中,bar()作为类方法调用会引发异常:

>>> Foo.bar('hello')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unbound method bar() must be called with Foo instance as first argument (got str instance instead)

>>> Foo.bar()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unbound method bar() must be called with Foo instance as first argument (got nothing instead)

当bar()作为实例方法调用时,它self在没有参数的情况下被识别为实例

>>> Foo().bar('hello')
Traceback (most recent …