# 4 Python中单下划线和双下划线

```python
#!/bin/env python3
# -*- coding: utf-8 -*-
# version: Python3.X
""" 讨论关于单下划线和双下划线命名的问题

总结:
    __foo__:一种约定,Python内部的名字,用来区别其他用户自定义的命名,以防冲突.
    _foo:一种约定,用来指定变量私有.程序员用来指定私有变量的一种方式.
    __foo:这个有真正的意义:解析器用_className__foo来代替这个名字,以区别和其他类相同的命名.
"""

__author__ = '__L1n__w@tch'


class UnderlineTest:
    def __init__(self):
        self.__super_private = "超级私有"
        self._semi_private = "假私有"


if __name__ == "__main__":
    ut = UnderlineTest()
    try:
        print(ut.__super_private)
    except AttributeError as e:
        print("[!] 找不到超级私有")
        print(e)

    print("寻找假私有{}: {}", "ut._semi_private", ut._semi_private)
    print("打印 __dict__: {}".format(ut.__dict__))
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://l1nwatch.gitbook.io/interview_exercise/python-yu-yan-te-xing/4-python-zhong-dan-xia-hua-xian-he-shuang-xia-hua-xian.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.