Python 小技巧 071：Python 编码风格检查
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：
pip install pycodestyle
使用
检测单个文件
假设现在有 demo.py ，内容如下：
# -*- coding: utf-8 -*-
a=2
print( 4 ,a)
在命令行中运行以下命令：
python -m pycodestyle --first 程序名.py
例如，想检测 demo.py 就运行以下命令：
python -m pycodestyle --first demo.py
执行结果：
demo.py:2:2: E225 missing whitespace around operator
demo.py:3:7: E201 whitespace after '('
demo.py:3:13: E203 whitespace before ','
demo.py:3:14: E231 missing whitespace after ','
demo.py:3:17: W292 no newline at end of file
其中这一部分：
demo.py:2:2
demo.py:3:7
demo.py:3:13
demo.py:3:14
demo.py:3:17
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：
demo.py:2:2: E225 运算符之间应该有空格
demo.py:3:7: E201 '(' 之后不应该有空格
demo.py:3:13: E203 ',' 之前不应该有空格
demo.py:3:14: E231 ',' 之后应该有空格
demo.py:3:17: W292 文件的末尾应该有
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：
python -m pycodestyle --show-source --show-pep8 程序名.py
还是以上面的 demo.py 为例：
python -m pycodestyle --show-source --show-pep8 demo.py
执行结果：
demo.py:2:2: E225 missing whitespace around operator
a=2
^
Surround operators with a single space on either side.
- Always surround these binary operators with a single space on
either side: assignment (=), augmented assignment (+=, -= etc.),
comparisons (==, <, >, !=, <=, >=, in, not in, is, is not),
Booleans (and, or, not).
- If operators with different priorities are used, consider adding
whitespace around the operators with the lowest priorities.
Okay: i = i + 1
Okay: submitted += 1
Okay: x = x * 2 - 1
Okay: hypot2 = x * x + y * y
Okay: c = (a + b) * (a - b)
Okay: foo(bar, key='word', *args, **kwargs)
Okay: alpha[:-i]
E225: i=i+1
E225: submitted +=1
E225: x = x /2 - 1
E225: z = x **y
E226: c = (a+b) * (a-b)
E226: hypot2 = x*x + y*y
E227: c = a|b
E228: msg = fmt%(errno, errmsg)
demo.py:3:7: E201 whitespace after '('
print( 4 ,a)
^
Avoid extraneous whitespace.
Avoid extraneous whitespace in these situations:
- Immediately inside parentheses, brackets or braces.
- Immediately before a comma, semicolon, or colon.
Okay: spam(ham, {eggs: 2})
E201: spam( ham, {eggs: 2})
E201: spam(ham[ 1], {eggs: 2})
E201: spam(ham, { eggs: 2})
E202: spam(ham, {eggs: 2} )
E202: spam(ham, {eggs: 2})
E202: spam(ham, {eggs: 2 })
E203: if x == 4: print x, y; x, y = y , x
E203: if x == 4: print x, y ; x, y = y, x
E203: if x == 4 : print x, y; x, y = y, x
demo.py:3:13: E203 whitespace before ','
print( 4 ,a)
^
Avoid extraneous whitespace.
Avoid extraneous whitespace in these situations:
- Immediately inside parentheses, brackets or braces.
- Immediately before a comma, semicolon, or colon.
Okay: spam(ham, {eggs: 2})
E201: spam( ham, {eggs: 2})
E201: spam(ham[ 1], {eggs: 2})
E201: spam(ham, { eggs: 2})
E202: spam(ham, {eggs: 2} )
E202: spam(ham, {eggs: 2})
E202: spam(ham, {eggs: 2 })
E203: if x == 4: print x, y; x, y = y , x
E203: if x == 4: print x, y ; x, y = y, x
E203: if x == 4 : print x, y; x, y = y, x
demo.py:3:14: E231 missing whitespace after ','
print( 4 ,a)
^
Each comma, semicolon or colon should be followed by whitespace.
Okay:
Okay: (3,)
Okay: a
Okay: a[:4]
Okay: a
Okay: a
E231: ['a','b']
E231: foo(bar,baz)
E231: [{'a':'b'}]
demo.py:3:17: W292 no newline at end of file
print( 4 ,a)
^
Trailing blank lines are superfluous.
Okay: spam(1)
W391: spam(1)\n
However the last line should end with a new line (warning W292).
可以看到 Pycodestyle 给出了详细的解释和建议的做法。 vscode和pycharm自带的code formatting感觉就很爽{:10_279:} python -m pycodestyle --first demo.py | clip
然后输出的信息就到了你剪切板里了{:10_256:}
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