[Python-Dev] Python environment registration in the Windows Registry

[Eric Snow]

On Tue, Feb 2, 2016 at 10:15 PM, Steve Dower <steve.dower at python.org> wrote:
> I was throwing around some ideas with colleagues about how we detect Python
> installations on Windows from within Visual Studio, and it came up that
> there are many Python distros that install into different locations but
> write the same registry entries. (I knew about this, of course, but this
> time I decided to do something.)
>
> [snip]
>
> So here is a rough proposal to standardise the registry keys that can be set
> on Windows in a way that (a) lets other installers besides the official ones
> have equal footing, (b) provides consistent search and resolution semantics
> for tools, and (c) includes slightly more rich metadata (such as display
> names and URLs). Presented in PEP-like form here, but if feedback suggests
> just putting it in the docs I'm okay with that too. It is fully backwards
> compatible with official releases of Python (at least back to 2.5, possibly
> further) and does not require modifications to Python or the official
> installer - it is purely codifying a superset of what we already do.
>
> Any and all feedback welcomed, especially from the owners of other distros,
> Python implementations or tools on the list.

Just wanted to quickly point out another use of the WIndows registry
in Python: WindowsRegistryFinder [1].  This is an import "meta-path"
finder that locates modules declared (*not* defined) in the registry.
I'm not familiar with the Windows registry nor do I know if anyone is
using this finder.  That said, ISTM the finder's use of the registry
does not face quite the same challenges you've described in the
proposal.  I expect Martin von Löwis could explain more as he was
involved with adding the finder.

Just wanted to throw that out there, particularly if there's a chance
of the finder's registry keys conflicting in some way.

-eric

[1] https://hg.python.org/cpython/file/5873cfb42ebe/Lib/importlib/_bootstrap_external.py#l570