I've seen recently some discussion in reddit about python 2 vs python 3, and the slow adoption of the latter. I am proposing here pragmatic way to speed up the process of porting old code and thus solving the split in the community, that I believe it is a serious threat. It is not clean, not at all, but it might work: just give python 2 whiners what they [we] want, and do it using "from __past__ import", in a similar way "from __future__ import" is used.

The advantage of this method is that porting old code would be trivial, and each module could be rewritten at its own pace (for example, when a new feature is required).

The 2to3.py tool could be updated to perform as many safe changes as it could (safe in the sense of 100% certainty of not breaking anything), and import old features as needed. I am thinking both in language syntax like division behaviour, unicode, str, etc, and major library changes. Past features may be added per request, and the 2to3 tool should allow users to force the use of any of them, just in case. The whole process should be almost automatic: the user might just run the tool at the root folder of the code base, with any required command-line arguments to force some features, and the tool would generate working python3 code.

There might be some issues regarding the interaction of new python3 code with code that uses old features, maintaining a more complex code base, and there might be other issues I am missing (like fundamental changes in python 3 internal architecture that can't accomodate some older features), but it might work and I think it could be useful to discuss this idea.

A potential non technical problem involves users abusing this mechanism to write new code with old features, but I believe it is a minor risk if this means the whole python community finally moves to python 3.

Hope this is useful.

Alejandro