Multiple statements on one line (colon)
Multiple statements should be on their own separate lines. This improves readability.
Anti-pattern
if x > 5: y = 10
Best practice
if x > 5:
y = 10
I’m using flake8 in Visual Studio Code, writing some code using Python 3.6 variable annotations. It worked without any problems so far, but I encountered a strange warning.
This works fine:
style: str = """
width: 100%;
...
"""
# Doing sth with `style`
This too:
img_style: str = """
width: 100%;
...
"""
# Doing sth with `img_style`
This however does not, it yields below warning:
iframe_style: str = """
width: 100%;
...
"""
# Doing sth with `iframe_style`
Well, technically it does work fine; the code runs. But somehow flake8 is not happy with this.
The multiline string and the code following is always the same.
When I omit the «f» (i_rame_style), I don’t get a warning, too! So I guess for some reason flake8 thinks of a if foo: bar() here!?
What am I missing here? Is this a bug in flake8?
asked Apr 11, 2018 at 11:50
linusglinusg
6,2334 gold badges28 silver badges77 bronze badges
6
Edit: The problem is in pycodestyle (pep8), which is called by flake8. The rest still stands.
Second edit: I’ve made some more research and the issue is fixed here. The fix hasn’t been released yet, though.
Definitely looks like a flake8 bug to me:
flakebug.py:
innocuous: str = ""
ifstarting_string: str = ""
forfalse_positivetoo: str = ""
whilethis_lookslikeabug: str = ""
elsehaha: str = ""
In the shell:
$ # python3.6 -m pycodestyle flakebug.py gives the same results
$ python3.6 -m flake8 flakebug.py
flakebug.py:2:18: E701 multiple statements on one line (colon)
flakebug.py:3:21: E701 multiple statements on one line (colon)
flakebug.py:4:24: E701 multiple statements on one line (colon)
flakebug.py:5:9: E701 multiple statements on one line (colon)
Looks like every line starting with a control flow statement triggers it.
I’d wager it uses a regex like (if|else|while|for).*:.
I’ll try to get to the bottom of this and update this answer if I can, meanwhile you could add some # noqa annotations and you’ll be set 
answered Apr 11, 2018 at 12:07
eteneetene
7004 silver badges12 bronze badges
4
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eddie-dunn
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Jun 9, 2017
If a Python 3 class variable begins with an indent keyword, i.e.,
class Class:
with_foo: int
pycodestyle will erroneously output the error 'E701 multiple statements
on one line'. This patch tightens the check so that even variables
beginning with indent keywords are allowed.
Resolves PyCQA#635
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With a new version of flake8 we can now stop ignoring E701 that was introduced to this bug: PyCQA/pycodestyle#635
LefterisJP
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With a new version of flake8 we can now stop ignoring E701 that was introduced to this bug: PyCQA/pycodestyle#635
hackaugusto
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With a new version of flake8 we can now stop ignoring E701 that was introduced to this bug: PyCQA/pycodestyle#635
Python’s PEP8 code specification, so record the common PEP8 code specification problems and solutions, learn it, and continue to update when you encounter it, develop good habits, and write standardized code!
PEP 8: no newline at end of file
Solution: You need to start a new line at the end of the code and move the cursor to the last carriage return
PEP 8: indentation is not a multiple of four
Solution: Indent is not a multiple of 4, check indent
PEP 8: over-indented
Solution: Excessive indentation, check indentation
PEP 8: missing whitespace after’,’
Solution: There are fewer spaces after the comma, just add spaces, similar to the semicolon or colon after the missing spaces
PEP 8: multiple imports on one line
Solution: Do not refer to multiple libraries in one sentence, for example:import socket, urllib.errorIt is best written as:import socket import urllib.error
PEP 8: blank line at end of line
Solution: There are more spaces at the end of the code, just delete the spaces
PEP 8: at least two spaces before inline comment
Solution: There must be at least two spaces between the code and the comment
PEP 8: block comment should start with ‘#’
Solution: The comment should start with # plus a space
PEP 8: inline comment should start with ‘#’
Solution: The comment should start with # plus a space
PEP 8: module level import not at top of file
Solution: import is not at the top of the file, there may be other code before
PEP 8: expected 2 blank lines，found 0
Solution: Two blank lines are needed, add two blank lines
PEP 8: function name should be lowercase
Solution: Change the function name to lower case
PEP 8: missing whitespace around operator
Solution: Operators (’=’, ‘>’, ‘<’, etc.) lack spaces before and after, just add
PEP 8: unexpected spaces around keyword / parameter equals
Solution: Unexpected spaces appear around the keyword / parameter equal sign, just remove the spaces
PEP 8: multiple statements on one line (colon)
Solution: The multi-line statement is written to one line, for example:if x == 2: print('OK')Write in two lines
PEP 8: line too long (82 > 79 characters)
Solution: The maximum length limit of each line is exceeded 79
PEP 8: Simplify chained comparison
can simplify chain comparisons (for example:if a >= 0 and a <= 9: Can be abbreviated as:if 0 <= a <= 9:）
If you want to selectively ignore the warning message of the PEP8 code style, you can use the following methods: (Cultivate good habits and write standardized code! It is not recommended to ignore!)
①Move the mouse to the place where the warning message appears, pressalt+Enter, Choose to ignore (Ignore) this error:
②Select one by oneFile — Settings — Editor — Inspections, Found under PythonPEP8 coding style violation Options, in the lower right cornerIgnore errors Click the plus sign to add the warning message ID that needs to be ignored (see the appendix for ID information), for example, you want to ignoreindentation contains mixed spaces and tabsFor this warning, just add its ID:E101 Just
Appendix: All warning messages and corresponding IDs, official address: 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 | Blank 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 |
Я использую flake8 в Visual Studio Code, пишу код с помощью Аннотации переменных Python 3.6. Пока все работало без проблем, но я столкнулся со странным предупреждением.
Это отлично работает:
style: str = """
width: 100%;
...
"""
# Doing sth with `style`
Это тоже:
img_style: str = """
width: 100%;
...
"""
# Doing sth with `img_style`
Однако это не так, это приводит к предупреждению ниже:
iframe_style: str = """
width: 100%;
...
"""
# Doing sth with `iframe_style`
Что ж, технически это работает нормально; код работает. Но почему-то flake8 это не устраивает. Многострочная строка и следующий за ней код всегда одинаковы.
Когда я опускаю букву «f» (i_rame_style), я тоже не получаю предупреждения! Так что, я думаю, по какой-то причине flake8 думает о if foo: bar() здесь !?
Что мне здесь не хватает? Это ошибка в flake8?
1 ответ
Лучший ответ
Изменить: проблема в pycodestyle (pep8), который вызывается flake8. Остальные по-прежнему в силе.
Второе изменение: я провел дополнительное исследование, и проблема исправлена здесь. Однако исправление еще не выпущено.
Для меня это определенно похоже на ошибку flake8:
flakebug.py:
innocuous: str = ""
ifstarting_string: str = ""
forfalse_positivetoo: str = ""
whilethis_lookslikeabug: str = ""
elsehaha: str = ""
В оболочке:
$ # python3.6 -m pycodestyle flakebug.py gives the same results
$ python3.6 -m flake8 flakebug.py
flakebug.py:2:18: E701 multiple statements on one line (colon)
flakebug.py:3:21: E701 multiple statements on one line (colon)
flakebug.py:4:24: E701 multiple statements on one line (colon)
flakebug.py:5:9: E701 multiple statements on one line (colon)
Похоже, что каждая строка, начинающаяся с оператора потока управления, запускает его. Держу пари, что здесь используется регулярное выражение вроде (if|else|while|for).*:.
Я постараюсь разобраться в этом и обновить этот ответ, если смогу, а пока вы можете добавить несколько аннотаций # noqa, и все будет готово
10
etene
11 Апр 2018 в 15:26