pylint检测git.exc相关代码出现E1101误报问题咨询

问题重现 #

先看这段能正常运行的Python代码：

import git
try:
    raise git.exc.GitCommandError("dummy", "foo")
except git.exc.GitCommandError as exc:
    print(exc)

但用pylint 2.3.1检测时，却弹出一堆E1101: no-member错误：

************* Module test
[无关错误已移除]
test.py:4:7: E1101: Instance of 'GitError' has no 'GitCommandError' member (no-member)
test.py:4:7: E1101: Instance of 'Exception' has no 'GitCommandError' member (no-member)
test.py:5:7: E1101: Instance of 'Exception' has no 'GitCommandError' member (no-member)
test.py:5:7: E1101: Instance of 'GitError' has no 'GitCommandError' member (no-member)
---------------------------------------------------------------------
Your code has been rated at -36.00/10 (previous run: 4.00/10, -40.00)

关键验证：git.exc是模块，不是异常 #

我特意在Python交互环境里确认了这点：

python3
Python 3.5.3 (default, Sep 27 2018, 17:25:39) [GCC 6.3.0 20170516] on linux
Type "help", "copyright", "credits" or "license" for more information.

import git
git.exc
<module 'git.exc' from '/tmp/tmp.ULCyvtUQWx/testenv/lib/python3.5/site-packages/GitPython-2.1.11-py3.5.egg/git/exc.py'>

结论：这是pylint的Bug，不是你的问题 #

你完全没有认知疏漏，这就是pylint静态分析的一个错误：

• pylint错误地把git.exc当成了GitError或者Exception的实例，而不是一个模块，所以它认为GitCommandError不是git.exc的成员。
• 至于用git.GitCommandError就没问题，是因为GitPython在顶层的git模块里已经导入了这个类，相当于做了个“快捷引用”，pylint能正确识别这个顶层的导出。

临时解决办法 #

如果想躲开这个错误，有两个选择：

• 直接用git.GitCommandError代替git.exc.GitCommandError，虽然后者才是类的原始定义路径；
• 在代码里加pylint的忽略注释，精准屏蔽这个错误：

  import git
  try:
      raise git.exc.GitCommandError("dummy", "foo")  # pylint: disable=no-member
  except git.exc.GitCommandError as exc:  # pylint: disable=no-member
      print(exc)
  

内容的提问来源于stack exchange，提问作者Frank Lichtenheld