false positive for catching-non-exception

[pylint-bot]

Originally reported by: Anonymous

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when i create a class that inherits from socket.error (which inherits from Exception), and use the new class in a try/except block, i receive a pylint error message stating that i am "catching a exception which doesn't inherit from BaseException: (catching-non-exception)"

eg:

from socket import error

class MyError(error): pass

try:
print 'a'
except MyError:
print 'b'

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• Bitbucket: https://bitbucket.org/logilab/pylint/issue/125

[pylint-bot]

Original comment by Claudiu Popa (BitBucket: PCManticore, GitHub: @PCManticore):

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Solved with https://bitbucket.org/logilab/pylint/pull-request/78/fix-false-positive-for-catching-non/diff. Thanks for the report!

[pylint-bot]

Original comment by BitBucket: benzionhain:

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Thanks for the quick response and fix.

another reason to love pylint :)

ben

[pylint-bot]

Original comment by Sylvain Thénault (BitBucket: sthenault, GitHub: @sthenault?):

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Removing version: 1.1 (automated comment)

[dhermes]

@PCManticore There may be a regression here, triggered in https://github.com/GoogleCloudPlatform/gcloud-python

To reproduce, install grpcio==0.15.0, then

"""Bogus docstring."""


from grpc.framework.interfaces.face import face

try:
    MY_GLOBAL = 11
except face.NetworkError:
    raise ValueError('Other error')

then the error is

$ pylint foo.py
No config file found, using default configuration
************* Module foo
E:  8, 7: Catching an exception which doesn't inherit from BaseException: NetworkError (catching-non-exception)

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But note that the MRO contains BaseException (and also Exception FWIW)

>>> from grpc.framework.interfaces.face import face
D0718 16:12:55.983836848   26996 ev_posix.c:101]             Using polling engine: poll
>>> face.NetworkError.__mro__
(<class 'grpc.framework.interfaces.face.face.NetworkError'>, <class 'grpc.framework.interfaces.face.face.AbortionError'>, <type 'exceptions.Exception'>, <type 'exceptions.BaseException'>, <type 'object'>)

It's possible that there is some sort of failure in the static analysis caused by usage of six.with_metaclass(abc.ABCMeta, Exception) in the parent?

[PCManticore]

@dhermes Should be fixed by 8d35557. Will release 1.6.4 later today or early tomorrow.

[dhermes]

@PCManticore You are awesome!