Installing configparser on Python 3.x is dangerous

[jaraco]

Original report by Barry Warsaw (Bitbucket: warsaw, GitHub: warsaw).

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Over in Ubuntu, we inherit Debian's python-configparser package, which currently provides configparser 3.3.0r2. Normally, this package isn't hugely depended on by other packages, so it doesn't get installed very often. Recently one of our main packages created a dependency on configparser and when it got installed lots of things broke. We ended up having to rewrite the code to not depend on configparser, and thus relegating it back away from our main repository. We must actively recommend against installing it.

Here are examples of things it broke. Some have been fixed in the broken package, but a few (e.g. the virtualenv problem) is currently fixable only by de-installing configparser.

https://bugs.launchpad.net/ubuntu/+source/python-virtualenv/+bug/1156704
https://bugs.launchpad.net/software-center/+bug/1038429
https://bugs.launchpad.net/ubuntu/+source/ubuntuone-client/+bug/1198480

Unfortunately, I don't have a lot of time right now for further investigation, but I wanted to file the bug upstream for tracking purposes.

[jaraco]

Original comment by Łukasz Langa (Bitbucket: ambv, GitHub: ambv).

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Barry, this library is a backport of configparser from 3.2+ to Python 2.6 and 2.7 only. It won't work on Python 3.x. On Python 3.2+ you should simply use configparser as provided by the standard library.

[jaraco]

Original comment by Barry Warsaw (Bitbucket: warsaw, GitHub: warsaw).

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Lukasz, you're right, but the problem is that installing configparser for Python 2 breaks virtualenv when creating a Python 3 virtualenv. We don't have a Python 3 version of python-configparser in the distro. Steps to reproduce on Debian:

#!

$ sudo apt-get install python-configparser
$ virtualenv --system-site-packages -p python3 /tmp/ve1
[traceback]
$ sudo apt-get purge python-configparser
$ virtualenv --system-site-packages -p python3 /tmp/ve2
[happy!]

[jaraco]

Original comment by Łukasz Langa (Bitbucket: ambv, GitHub: ambv).

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I'm sorry you had to wait so long for this to be resolved. Fixed in 3.5.0b1.

[jaraco]

Original comment by Marc Abramowitz (Bitbucket: msabramo, GitHub: msabramo).

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Wondering if you can release 3.5.0 to PyPI?

https://pypi.python.org/pypi/configparser/ has 3.5.0b2 as the latest version, which is a pre-release.

As a result when I do pip install -v configparser, I get:

$ pip install -v configparser
Downloading/unpacking configparser
  Ignoring link https://pypi.python.org/packages/source/c/configparser/configparser-3.5.0b1.tar.gz#md5=d60ca2c714acb4adaf5818c6a1ffd78b (from https://pypi.python.org/simple/configparser/), version 3.5.0b1 is a pre-release (use --pre to allow).
  Ignoring link https://pypi.python.org/packages/source/c/configparser/configparser-3.5.0b2.tar.gz#md5=ad2a71db8bd9a017ed4735eac7acfa07 (from https://pypi.python.org/simple/configparser/), version 3.5.0b2 is a pre-release (use --pre to allow).
  Using version 3.3.0r2 (newest of versions: 3.3.0r2, 3.3.0r1, 3.2.0r3, 3.2.0r2, 3.2.0r1)
  Downloading configparser-3.3.0r2.tar.gz
...

$ pip freeze | grep -i configparser
configparser==3.3.0r2

$ virtualenv --python python3.3 py33
Running virtualenv with interpreter /Library/Frameworks/Python.framework/Versions/3.3/bin/python3.3
Traceback (most recent call last):
  File "/Users/marca/python/virtualenvs/configparser/lib/python2.7/site-packages/virtualenv.py", line 41, in <module>
    import ConfigParser
ImportError: No module named 'ConfigParser'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/marca/python/virtualenvs/configparser/lib/python2.7/site-packages/virtualenv.py", line 43, in <module>
    import configparser as ConfigParser
  File "/Users/marca/python/virtualenvs/configparser/lib/python2.7/site-packages/configparser.py", line 397
    _KEYCRE = re.compile(ur"%\(([^)]+)\)s")
                                         ^
SyntaxError: invalid syntax