Python | single underline and double underline accessibility

Environmental Science : Python 3.10.4

1. summary

Put the summary first

Underline Double underline Class properties and methods TrueFalse Subclasses call parent class properties and methods TrueFalse Module function TrueTrue

In the actual development process , Calling... Is strongly deprecated _ or __ Content at the beginning , image __str__ Except for .

2. class

2.1. attribute

class Hello:
def __init__(self, one, two):
self._one = one
self.__two = two
h = Hello(1, 2)
print(h._one)
print(h.__two)

Output

1
Traceback (most recent call last):
File "/Users/yimt/Code/PycharmProjects/hello-python/hello.py", line 9, in <module>
print(h.__two)
AttributeError: 'Hello' object has no attribute '__two'

2.2. Method

class Hello:
def _one(self):
print('one')
def __two(self):
print('two')
h = Hello()
h._one()
h.__two()

Output

Traceback (most recent call last):
File "/Users/yimt/Code/PycharmProjects/hello-python/learn.py", line 1, in <module>
import hello
File "/Users/yimt/Code/PycharmProjects/hello-python/hello.py", line 11, in <module>
h.__two()
AttributeError: 'Hello' object has no attribute '__two'
one

3. modular

The program runs normally

hello.py

def _one():
print('one')
def __two():
print('two')

main.py

import hello
hello._one()
hello.__two()

Output

one
two