Python 小技巧 071：Python 编码风格检查

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Python 编码风格检查

Pycodestyle 是一个第三方库，它用于对 Python 程序进行代码风格的检查（遵循 PEP8 中定义的规范）。

安装

直接在命令行使用 pip 安装即可：

1. pip install pycodestyle

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使用

检测单个文件

假设现在有 demo.py ，内容如下：

1. # -*- coding: utf-8 -*-
   
2. a=2
   
3. print(     4 ,a)

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在命令行中运行以下命令：

1. python -m pycodestyle --first 程序名.py

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例如，想检测 demo.py 就运行以下命令：

1. python -m pycodestyle --first demo.py

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执行结果：

1. demo.py:2:2: E225 missing whitespace around operator
   
2. demo.py:3:7: E201 whitespace after '('
   
3. demo.py:3:13: E203 whitespace before ','
   
4. demo.py:3:14: E231 missing whitespace after ','
   
5. demo.py:3:17: W292 no newline at end of file

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其中这一部分：

1. demo.py:2:2
   
2. demo.py:3:7
   
3. demo.py:3:13
   
4. demo.py:3:14
   
5. demo.py:3:17

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详细地交代了出现不符合规范的地方，用英文冒号分隔。第一个元素是文件名，第二个元素是出问题的行号，第三个元素是出问题的字符在行中的位置。

稍稍翻译一下：

1. demo.py:2:2: E225 运算符之间应该有空格
   
2. demo.py:3:7: E201 '(' 之后不应该有空格
   
3. demo.py:3:13: E203 ',' 之前不应该有空格
   
4. demo.py:3:14: E231 ',' 之后应该有空格
   
5. demo.py:3:17: W292 文件的末尾应该有

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可以按照给出的提示更改程序代码，使代码变得更美观。

说明：如果程序代码完全符合规范，则没有输出。

显示详细信息

在命令行中运行以下命令：

1. python -m pycodestyle --show-source --show-pep8 程序名.py

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还是以上面的 demo.py 为例：

1. python -m pycodestyle --show-source --show-pep8 demo.py

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执行结果：

1. demo.py:2:2: E225 missing whitespace around operator
   
2. a=2
   
3. ^
   
4.     Surround operators with a single space on either side.
   
5. 
   
6.     - Always surround these binary operators with a single space on
   
7.       either side: assignment (=), augmented assignment (+=, -= etc.),
   
8.       comparisons (==, <, >, !=, <=, >=, in, not in, is, is not),
   
9.       Booleans (and, or, not).
   
10. 
    
11.     - If operators with different priorities are used, consider adding
    
12.       whitespace around the operators with the lowest priorities.
    
13. 
    
14.     Okay: i = i + 1
    
15.     Okay: submitted += 1
    
16.     Okay: x = x * 2 - 1
    
17.     Okay: hypot2 = x * x + y * y
    
18.     Okay: c = (a + b) * (a - b)
    
19.     Okay: foo(bar, key='word', *args, **kwargs)
    
20.     Okay: alpha[:-i]
    
21. 
    
22.     E225: i=i+1
    
23.     E225: submitted +=1
    
24.     E225: x = x /2 - 1
    
25.     E225: z = x **y
    
26.     E226: c = (a+b) * (a-b)
    
27.     E226: hypot2 = x*x + y*y
    
28.     E227: c = a|b
    
29.     E228: msg = fmt%(errno, errmsg)
    
30. demo.py:3:7: E201 whitespace after '('
    
31. print(     4 ,a)
    
32.       ^
    
33.     Avoid extraneous whitespace.
    
34. 
    
35.     Avoid extraneous whitespace in these situations:
    
36.     - Immediately inside parentheses, brackets or braces.
    
37.     - Immediately before a comma, semicolon, or colon.
    
38. 
    
39.     Okay: spam(ham[1], {eggs: 2})
    
40.     E201: spam( ham[1], {eggs: 2})
    
41.     E201: spam(ham[ 1], {eggs: 2})
    
42.     E201: spam(ham[1], { eggs: 2})
    
43.     E202: spam(ham[1], {eggs: 2} )
    
44.     E202: spam(ham[1 ], {eggs: 2})
    
45.     E202: spam(ham[1], {eggs: 2 })
    
46. 
    
47.     E203: if x == 4: print x, y; x, y = y , x
    
48.     E203: if x == 4: print x, y ; x, y = y, x
    
49.     E203: if x == 4 : print x, y; x, y = y, x
    
50. demo.py:3:13: E203 whitespace before ','
    
51. print(     4 ,a)
    
52.             ^
    
53.     Avoid extraneous whitespace.
    
54. 
    
55.     Avoid extraneous whitespace in these situations:
    
56.     - Immediately inside parentheses, brackets or braces.
    
57.     - Immediately before a comma, semicolon, or colon.
    
58. 
    
59.     Okay: spam(ham[1], {eggs: 2})
    
60.     E201: spam( ham[1], {eggs: 2})
    
61.     E201: spam(ham[ 1], {eggs: 2})
    
62.     E201: spam(ham[1], { eggs: 2})
    
63.     E202: spam(ham[1], {eggs: 2} )
    
64.     E202: spam(ham[1 ], {eggs: 2})
    
65.     E202: spam(ham[1], {eggs: 2 })
    
66. 
    
67.     E203: if x == 4: print x, y; x, y = y , x
    
68.     E203: if x == 4: print x, y ; x, y = y, x
    
69.     E203: if x == 4 : print x, y; x, y = y, x
    
70. demo.py:3:14: E231 missing whitespace after ','
    
71. print(     4 ,a)
    
72.              ^
    
73.     Each comma, semicolon or colon should be followed by whitespace.
    
74. 
    
75.     Okay: [a, b]
    
76.     Okay: (3,)
    
77.     Okay: a[1:4]
    
78.     Okay: a[:4]
    
79.     Okay: a[1:]
    
80.     Okay: a[1:4:2]
    
81.     E231: ['a','b']
    
82.     E231: foo(bar,baz)
    
83.     E231: [{'a':'b'}]
    
84. demo.py:3:17: W292 no newline at end of file
    
85. print(     4 ,a)
    
86.                 ^
    
87.     Trailing blank lines are superfluous.
    
88. 
    
89.     Okay: spam(1)
    
90.     W391: spam(1)\n
    
91. 
    
92.     However the last line should end with a new line (warning W292).

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可以看到 Pycodestyle 给出了详细的解释和建议的做法。

Levin-e

vscode和pycharm自带的code formatting感觉就很爽

_2_

1. python -m pycodestyle --first demo.py | clip

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然后输出的信息就到了你剪切板里了