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This patch adds a dropdown to python documentation top toolbar:
https://dl.dropbox.com/u/21052/python/p3_doc_dd.png
This patch version is for python 3.3 & 3.4 docs theme, but I can quickly make patches for 3.2-style and below.
JavaScript that monitors dropdown events is smart enough to:
1) Redirect users to the same documentation section, i.e. if the user is on 'atexit' module doc page for 3.3, and decides to switch to '2.7', he'll see 'atexit' module doc page for 2.7
2) Before making a redirect, is checks that the doc page exists for the selected python version, and if not, then it simply redirects to 'http://docs.python.org/{version}'
3) Users with JS disabled will see a plain-text current version (no drop down)

Thanks for the patch.
What happens if the module doesn't exist in a previous version or if it has a different name?
It's probably not necessary to include all those versions.

> What happens if the module doesn't exist in a previous version or if it has a different name?
As I said in the first message:
"""
2) Before making a redirect, is checks that the doc page exists for the selected python version, and if not, then it simply redirects to 'http://docs.python.org/{version}'
"""
That's the most sane method I can imagine.

I left a review on rietveld.
FWIW we discussed this already somewhere, and IIRC the two main issues were:
1) mapping new/renamed/delete files between versions;
2) making this work while building the docs locally;
Redirecting to 'http://docs.python.org/{version}' might be an acceptable solution for 1) if we don't want to keep lists of module names.
Regarding 2) it depends on the local directory layout, so it would need to be configurable.
These are just further enhancements though, I think it would be good to have something similar even if it doesn't cover all the possible cases.

See #8040.

> 1) mapping new/renamed/delete files between versions;
I think that this dropdown is mostly like to be used to switch between somewhat recent python versions, like '3.2' -> '3.3', '2.7' -> '3.3', and not between '2.4' -> '3.4'
And most of the internet links point to plain 'docs.python.org', without version at all.
> 2) making this work while building the docs locally;
I think we need to make this JS dropdown to be off by default; so local users won't notice a thing.

> I think that this dropdown is mostly like to be used to switch between 
> somewhat recent python versions, like '3.2' -> '3.3', '2.7' -> '3.3',
> and not between '2.4' -> '3.4'
I mostly want to switch between 2.x and 3.x, and several modules got renamed between these versions. There are also new modules on each release (5 new ones in 3.3).
> I think we need to make this JS dropdown to be off by default;
> so local users won't notice a thing.
Even better would be to make it work -- while fixing the docs I often have to apply a patch on each version and then check that it works. If that's not implemented, disabling it sounds OK. By now I'm used to just change the URLs (I do the same even on docs.python.org), but it would be a nice addition.
These are just further improvements though, they don't necessarily prevent the current patch to be accepted.

> I mostly want to switch between 2.x and 3.x, and several modules got renamed between these versions. There are also new modules on each release (5 new ones in 3.3).
To make that work we'll need to have a modules mapping between 2nd and 3rd versions. It will also make URL parsing/changing logic more complicated and error prone...

Eric,
I'm not sure what we should do with #8040. I searched for the existing issue before creating a new one, but obviously failed. Should we just close #8040 and point it to #16331?

Typically we close the newer issue as duplicate of the existing one, unless the new has much more discussion or patches. I would close this one.
About renamed modules: there’s a mapping in lib2to3 that contains the info.

Eric, Ezio,
This one has a patch attached with a relevant discussion & review, so I'd close #8040.
But if you guys decide to close this one and switch to #8040 - i'm fine.

I recommend closing this as a duplicate.

yselivanov: please resubmit the patch to the original issue.