Discontinuing support for Python 2.7 on April 15, 2018

[tleonhardt]

Supporting multiple old versions of Python is becoming more and more burdensome as good features get added to newer versions of Python which don't get back-ported to older versions.

I don't want to abandon support for versions of Python that users are actively using. But I also don't want to waste developer time supporting versions nobody cares about.

So whoever reads this, please feel free to add a comment and say what versions of Python you care about cmd2 supporting now and in the near future.

[tleonhardt]

I only care about Python 3.5, 3.6, and 3.7 at this time. Supporting each of those versions is important to me for the foreseeable future.

[kotfu]

3.4+ for me, although I could be persuaded to discontinue support for 3.4.

As an only partially relevant data point, the Requests library supports 2.6, 2.7, 3.4, 3.5, 3.6 and 3.7.

I also think the Python community has kept 2.7 viable much longer than necessary. Python 3 has been out for nine years.

[tleonhardt]

@kotfu Last night I merged in a change where for Python 3.4 and earlier there is now an additional dependency on contextlib2. Does that affect you negatively at all? I hope not. This was in pursuit of having help provide output to stdout for commands using one of the argparse decorators. For 3.5+ all the good stuff in contextlib2 got merged into the built-in contextlib.

What do you think a reasonable policy would be for announcing an end-of-life for cmd supporting Python 2.7 for new releases? Would you prefer it to be based on date (i.e. something like Dec. 31, 2018) or release (i.e. something like 0.8.x)?

Regardless, I would like to somehow give some sort of notice that support will be ending for Python 2.7 in the not-too-distant future and end users know what they can expect. Of course, older versions of cmd2 could still be used with Python 2.7, we just won't be supporting it in newer versions.

[kotfu]

The additional contextlib2 dependency is no problem for me.

I think we should choose some date when we will no longer be supporting python 2.x. On that date, we make a new release (i.e. 0.12.0 or whatever) that does not run tests against python 2.x and which states that there is no support for python 2.x. Then we can begin cleaning up the 2.x cruft, like the six library and the contextlib2 thing you just added.

[tleonhardt]

Ok, I like the date-based approach? When do you think a good date would be? The latest I would want it to be would be the end of 2018. But I would be happy with earlier in the year. I look forward to cleaning up the codebase by removing the 2.x cruft. And I would love to start being able to use optional type hints for arguments and return values.

[kotfu]

What about end of summer? We give ~ 6 months notice and discontinue support for Python 2.x on Aug 31, 2018.

[tleonhardt]

Discontinuing support for Python 2.7 on Aug 31, 2018 sounds good to me.

[tleonhardt]

@kotfu What would you think about moving the date we stop supporting Python 2.7 up a little bit so it happens sooner? I've received multiple complaints from other cmd2 developers that continuing to support Python 2.7 is a significant burden. Maybe May 31, 2018 or April 30, 2018 could be a possibility?