python - 这个地方的_b和b有什么区别

Question

class a:
    def __init__(self):
        self._b()#why here use _b,not b,What's the difference
        self._c='cccc'#why here use _c,not c,What's the difference
    def _b():
        print 'bbbb'

a.py

class a:
    def __init__(self):
        self._b()#why here use _b,not b,What's the difference
        self._c='cccc'#why here use _c,not c,What's the difference
    def _b(self):
        print 'bbbb'

b.py

from  a import *
b=a()
b._b()
print b._c

它打印bbbbbbbbbbbbbbbbcccc

为什么能打印出这些，不就是_b和_c私有(private)变量吗。

Answer 1

在变量名或函数名前加下划线是 Python 中的一种约定，表示该变量是私有(private)的。来自 the docs :

Private” instance variables that cannot be accessed except from inside an object, don’t exist in Python. However, there is a convention that is followed by most Python code: a name prefixed with an underscore (e.g. _spam) should be treated as a non-public part of the API (whether it is a function, a method or a data member). It should be considered an implementation detail and subject to change without notice.