产生元组的无意尾随逗号 [英] Unintentional trailing comma that creates a tuple
问题描述
在Python中,这样的结尾逗号当然不是SyntaxError
:
In Python, leaving a trailing comma like this is, of course, not a SyntaxError
:
In [1]: x = 1 ,
In [2]: x
Out[2]: (1,)
In [3]: type(x)
Out[3]: tuple
但是,与此同时,如果尾随逗号被误加了 ,则可能很难抓住这种问题",尤其是对于Python新手.
But, at the same time, if the trailing comma was put accidentally, it may be difficult to catch this kind of a "problem", especially for Python newcomers.
我正在考虑是否可以借助PyCharm
智能代码质量控制功能来静态地尽早地解决这种问题" ; mypy
,pylint
或flake8
静态代码分析工具.
I am thinking if we can catch this kind of a "problem" early, statically, with the help of PyCharm
smart code quality control features; mypy
, pylint
or flake8
static code analysis tools.
或者,另一种想法是限制/突出显示无括号的隐式创建一个元组.有可能吗?
Or, another idea would be to restrict/highlight creating one item tuples implicitly without parenthesis. Is it possible?
推荐答案
pylint
already detects this as a problem (as of version 1.7).
例如,这是我的tuple.py
:
"""Module docstring to satisfy pylint"""
def main():
"""The main function"""
thing = 1,
print(type(thing))
if __name__ == "__main__":
main()
$ pylint tuple.py
No config file found, using default configuration
************* Module tuple
R: 5, 0: Disallow trailing comma tuple (trailing-comma-tuple)
------------------------------------------------------------------
Your code has been rated at 8.00/10 (previous run: 8.00/10, +0.00)
$ pylint --help-msg trailing-comma-tuple
No config file found, using default configuration
:trailing-comma-tuple (R1707): *Disallow trailing comma tuple*
In Python, a tuple is actually created by the comma symbol, not by the
parentheses. Unfortunately, one can actually create a tuple by misplacing a
trailing comma, which can lead to potential weird bugs in your code. You
should always use parentheses explicitly for creating a tuple. This message
belongs to the refactoring checker. It can't be emitted when using Python <
3.0.
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