创建元组的无意尾随逗号

Question

在Python中，像这样在尾部留一个逗号，当然不是SyntaxError:

In [1]: x = 1 ,

In [2]: x
Out[2]: (1,)

In [3]: type(x)
Out[3]: tuple

但是，同时，如果尾部的逗号不小心，可能很难捕捉到这种"problem"，尤其是Python新人。

我在想我们是否可以在 "problem" 早期 静态地捕获这种 PyCharm 智能代码质量控制功能； mypy、pylint 或 flake8 静态代码分析工具。

或者，另一种想法是 restrict/highlight 隐式创建一个没有括号的项目元组 。可能吗？

Answer 1

pylint已经检测到这是一个问题 (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.

创建元组的无意尾随逗号

Unintentional trailing comma that creates a tuple

python

pycharm

pylint

static-code-analysis

flake8