self in Python

Z.ZHANG

3 月 30, 2017 1 min read

‘self’ represents instance, rather than the class.
When we are running t.prt(), actually we are running Test.prt(t).

Class Test:
    def prt(self):
        print(self)

t = Test()
t.prt()

The Class Method: (Not passing self when we are defining and calling the function.)

class Test:
    def prt():
        print(__class__)
Test.prt()

在继承时，传入的是哪个实例，那么父类中运行的也是这个实例。
在描述符类中，self指的是描述符类的实例。

class Desc:
    def __get__(self, ins, cls):
        print('self in Desc: %s ' % self )
        print(self, ins, cls)
class Test:
    x = Desc()
    def prt(self):
        print('self in Test: %s' % self)
t = Test()
t.prt()
t.x

运行结果：

self in Test: <__main__.Test object at 0x0000000002A570B8>
self in Desc: <__main__.Desc object at 0x000000000283E208>
<__main__.Desc object at 0x000000000283E208> <__main__.Test object at 0x0000000002A570B8> <class '__main__.Test'>

Reference: 一篇文章让你彻底搞清楚Python中self的含义