python coding standards from PEP8
写在前面
A Foolish Consistency is the Hobgoblin of Little Minds!
尽信书，则不如无书！这是从pep8规范上摘抄下来的话，正如代码规范是为了提升代码阅读和编码质量一样，任何规范的首要原则就是一致性。我们应该遵循已经存在了的项目代码风格，而不要为了规范而特意打破原来的平衡，当然如果你重头开始一个新的项目，那么最好使用这些约定来帮助你和他人更好的理解和阅读代码。
一行代码学习完所有规范
>>>pip install flake8 # or
>>>pip install pylint
最好的学习方式就是安装上述代码规范检查工具，当然并不限于以上两种，这类的规范工具很多，选择一种适合自己的且只安装一种，因为它们之间也会为了某些标准而打架。当然如果你并不满意或者不需要某种规范，可以按照下载工具的官方文档去设置忽略它们，毕竟自己码代码码的开心才最重要！
还是要学习如何写
尽管我们可以安装工具来规范自己，时刻提醒自己，但不学习如何规范的编写，到时候满屏的波浪线会让你崩溃。下面是我自己总结的一些基础的编码风格和规范，我会按照编写一个py文件的顺序来介绍。
一个固定的开头
#!/usr/bin/python
# -*- coding: utf-8 -*-
"""My favorite way.
first line: use absolute path of python.
second line: appoint the encode of file.
"""
#!/usr/bin/env python
"""Another way.
use env path better than the way above.
"""
#!/usr/bin/python2
"""python2!"""
#!/usr/bin/python3
"""python3!"""
# coding: utf-8
# coding=utf-8
"""A short way.
but I don't think it beautiful than my way just in format.
"""
正如你所看到那样，仅仅开头就花样百出。但我仍然没有列出所有的方式，你也不必纠结有多少种写法，选择一种你最喜欢的方式足以。
那么为啥要写这两行呢？
-
#!/usr/bin/python
指定所用的python解释器，python后面的数字指定python版本；当然这行代码在windows下意义不大，主要是针对linux/unix用户，如果在linux/unix下加上这行代码，并且当前用户对py文件拥有可执行权限的话，可以在终端直接输入./filename.py执行py文件（验证时请注意使用ls -all查看权限，有时root也不一定拥有可执行权限，使用chmod进行修改即可验证）。不加这行代码或者当前用户没有权限，则使用python filename.py执行。 -
-*- coding: utf-8 -*-
指定文件编码，这个主要是针对python2的py文件中如果出现非ASCII字符会报错，即使是在注释中；而python3默认utf-8编码，可以不加此行代码，但为了代码的可移植性，请务必添加。
规范使用import
import sys # first import the standard library
# put a blank line
import requests # then import the third party
# put a blank line
import my_module # finally use own module
import os, sys # don't use this, separate them in different line
# import like this
import os
import sys
# this is ok
from subprocess import Popen, PIPE
# try not use this as possible as you can
from os import *
开始正式码代码
- 代码编排
1 import os
2
3
4 # put two blank lines
5 class CodeStyle:
6
7 def use_four_space_for_indent(self):
8 """Four space for indent."""
9 pass
10
11 def put_one_blank_line(self):
12 """One blank line between the class method."""
13 pass
14
15
16 def alone_function():
17 """Get two blank lines between the class."""
18 pass
19
20
21 if __name__ == '__main__':
22 """Also two lines."""
23 print('the last line!') # put a blank line in the last, like code line mark number 24
24
- 命名规范
# use some meaningful words
import my_module # lowercase, use underscore
THE_CONSTANT_NAME = 1 # uppercase, use underscore
class MyClass: # CapWords
def __init__(self):
self.the_class_attr = 1 # lowercase, use underscore
def class_method_name(self): # lowercase, use underscore
pass
def the_function_name(param_name): # lowercase, use underscore
the_variable_name = 1 # lowercase, use underscore
- 有趣的空格
# use like this
x = 1
y = 1
long_variable = 3
# don't
x = 1
y = 1
long_variable = 3
# no space between '=', but still has one space in parameters
def function1(param1, param2, param3=3):
return function2(param1=1, param2=2)
# some more examples
# yes
i = i + 1
submitted += 1
x = x*2 - 1
hypot2 = x*x + y*y
c = (a+b) * (a-b)
# No
i=i+1
submitted +=1
x = x * 2 - 1
hypot2 = x * x + y * y
c = (a + b) * (a - b)
# Yes
if foo == 'hehe':
return True
for i in list:
x += i
while True:
do_this()
# No
if foo == 'hehe': return True
for i in list: x += i
while True: do_this()
# comment
# there has one space after '#'
- 文档和注释
#!/usr/bin/python
# -*- coding: utf-8 -*-
"""Module document.
use """ """, write something important.
first line first word in document uppercase.
the module document before import statement,
like this.
"""
import my_module
class MyClass:
"""MyClass document, single line."""
# or
"""MyClass document.
multi-line.
and many words.
and...
"""
def __init__(self):
"""Init the object."""
pass
def function(param1, param2):
"""
This is a groups style docs from google.
Parameters:
param1 - this is the first param
param2 - this is a second param
Returns:
This is a description of what is returned
Raises:
KeyError - raises an exception
"""
pass
# and this is a single comment， notice the space after '#'
# we should use English comment as possible as we can.
# it can improve our language sense, so you can see it
# why I try to write so many poor English comments and
# I'm just kidding. that's advice from pep8, but we
# should follow our project language that the most people
# can accept it. notice use two space after a
# sentence-ending period in multi-sentence comments,
# except the last one.
#
# the best way to write comment is don't use two language
# in comments!
编码结束
have fun in python!
