Python编译过程中出现波浪线等代码规范问题常见解决方法

在Pycharm波浪线经常出现在编译程序中。当你不知道有什么问题时，你可以把鼠标移到波浪线上，查看提示信息，然后在下面PEP在代码规范问题上寻找解决方案

以下是常见的 PEP8 代码规范和解决方法

PEP 8: no newline at end of file
解决方案:代码末尾需要另一行，光标可以移到最后回车

PEP 8: indentation is not a multiple of four
解决方法：缩进不是4倍，检查缩进

PEP 8: over-indented
解决方法：过度缩进，检查缩进

PEP 8: missing whitespace after’,’
解决方法:逗号后面空格少，加空格就行了，类似分号或者冒号后面空格少。

PEP 8: multiple imports on one line
解决方法：不要说一句话 import 以中引用多个库为例：import socket, urllib.error最好写成：import socket import urllib.error

PEP 8: blank line at end of line
解决方案：代码末尾有更多的空格，可以删除空格

PEP 8: at least two spaces before inline comment
解决方案：代码和注释之间至少有两个空间

PEP 8: block comment should start with ‘#’
解决方案：注释应从#添加空间开始

PEP 8: inline comment should start with ‘#’
解决方案：注释应从#添加空间开始

PEP 8: module level import not at top of file
解决方法：import不在文件的顶部，以前可能还有其他代码

PEP 8: expected 2 blank lines，found 0
解决方案:需要两条空白线，加两条空白线

PEP 8: function name should be lowercase
解决方法：将函数名改为小写

PEP 8: missing whitespace around operator
解决方法：操作符(‘操作符’=’、’>’、’<前后缺少空间，可以加上

PEP 8: unexpected spaces around keyword / parameter equals
解决方法:关键字/参数等号周围出现意外空格，可以去除空格

PEP 8: multiple statements on one line (colon)
解决方法：一行写多行语句，如：if x == 2: print(‘OK分两行写

PEP 8: line too long (82 > 79 characters)
解决方案:超过每行最大长度限制79

PEP 8: Simplify chained comparison
可简化连锁比较(如:if a >= 0 and a <= 9: 可简写为：if 0 <= a <= 9:）

若要选择性地忽略PEP8代码风格的警告信息可采用以下方法：（养成良好习惯，编写标准代码！不建议忽略！

①将鼠标移到有警告信息的地方，按下 alt Enter，选择忽略（Ignore）这个错误可以：

②依次选择 File - Settings - Editor - Inspections，在 Python下找到 PEP8 coding style violation 选项，在右下角 Ignore errors 点击加号添加需要忽略的警告信息ID（ID信息见附录)，比如想忽略indentation contains mixed spaces and tabs这个警告只需要添加ID：E101 即可

附录：所有警告信息及相应的ID，官方地址：https://pep8.readthedocs.io/en/latest/intro.html#error-codes

code sample message
E1 Indentation
E101 indentation contains mixed spaces and tabs
E111 indentation is not a multiple of four
E112 expected an indented block
E113 unexpected indentation
E114 indentation is not a multiple of four (comment)
E115 expected an indented block (comment)
E116 unexpected indentation (comment)
E117 over-indented
E121 (^) continuation line under-indented for hanging indent
E122 (^) continuation line missing indentation or outdented
E123 () closing bracket does not match indentation of opening bracket’s line
E124 (^) closing bracket does not match visual indentation
E125 (^) continuation line with same indent as next logical line
E126 (^) continuation line over-indented for hanging indent
E127 (^) continuation line over-indented for visual indent
E128 (^) continuation line under-indented for visual indent
E129 (^) visually indented line with same indent as next logical line
E131 (^) continuation line unaligned for hanging indent
E133 () closing bracket is missing indentation
E2 Whitespace
E201 whitespace after ‘(‘
E202 whitespace before ‘)’
E203 whitespace before ‘:’
E211 whitespace before ‘(‘
E221 multiple spaces before operator
E222 multiple spaces after operator
E223 tab before operator
E224 tab after operator
E225 missing whitespace around operator
E226 () missing whitespace around arithmetic operator
E227 missing whitespace around bitwise or shift operator
E228 missing whitespace around modulo operator
E231 missing whitespace after ‘,’, ‘;’, or ‘:’
E241 () multiple spaces after ‘,’
E242 () tab after ‘,’
E251 unexpected spaces around keyword / parameter equals
E261 at least two spaces before inline comment
E262 inline comment should start with ‘# ‘
E265 block comment should start with ‘# ‘
E266 too many leading ‘#’ for block comment
E271 multiple spaces after keyword
E272 multiple spaces before keyword
E273 tab after keyword
E274 tab before keyword
E275 missing whitespace after keyword
E3 Blan line
E301 expected 1 blank line, found 0
E302 expected 2 blank lines, found 0
E303 too many blank lines (3)
E304 blank lines found after function decorator
E305 expected 2 blank lines after end of function or class
E306 expected 1 blank line before a nested definition
E4 Import
E401 multiple imports on one line
E402 module level import not at top of file
E5 Line length
E501 (^) line too long (82 > 79 characters)
E502 the backslash is redundant between brackets
E7 Statement
E701 multiple statements on one line (colon)
E702 multiple statements on one line (semicolon)
E703 statement ends with a semicolon
E704 () multiple statements on one line (def)
E711 (^) comparison to None should be ‘if cond is None:’
E712 (^) comparison to True should be ‘if cond is True:’ or ‘if cond:’
E713 test for membership should be ‘not in’
E714 test for object identity should be ‘is not’
E721 (^) do not compare types, use ‘isinstance()’
E722 do not use bare except, specify exception instead
E731 do not assign a lambda expression, use a def
E741 do not use variables named ‘l’, ‘O’, or ‘I’
E742 do not define classes named ‘l’, ‘O’, or ‘I’
E743 do not define functions named ‘l’, ‘O’, or ‘I’
E9 Runtime
E901 SyntaxError or IndentationError
E902 IOError
W1 Indentation warning
W191 indentation contains tabs
W2 Whitespace warning
W291 trailing whitespace
W292 no newline at end of file
W293 blank line contains whitespace
W3 Blank line warning
W391 blank line at end of file
W5 Line break warning
W503 () line break before binary operator
W504 () line break after binary operator
W505 (*^) doc line too long (82 > 79 characters)
W6 Deprecation warning
W601 .has_key() is deprecated, use ‘in’
W602 deprecated form of raising exception
W603 ‘<>’ is deprecated, use ‘!=’
W604 backticks are deprecated, use ‘repr()’
W605 invalid escape sequence ‘x’
W606 ‘async’ and ‘await’ are reserved keywords starting with Python 3.7