[Python-Dev] mimetypes and _winreg

Mike Brown mike at skew.org
Wed Feb 2 01:50:51 CET 2005

Following up on this 12 Jun 2004 post...

Garth wrote:
> Thomas Heller wrote:
> >Mike Brown <mike at skew.org> writes:
> >>I thought it would be nice to try to improve the mimetypes module by having 
> >>it, on Windows, query the Registry to get the mapping of filename extensions 
> >>to media types, since the mimetypes code currently just blindly checks 
> >>posix-specific paths for httpd-style mapping files. However, it seems that the 
> >>way to get mappings from the Windows registry is excessively slow in Python.
> >>
> >>I'm told that the reason has to do with the limited subset of APIs that are 
> >>exposed in the _winreg module. I think it is that EnumKey(key, index) is 
> >>querying for the entire list of subkeys for the given key every time you call 
> >>it. Or something. Whatever the situation is, the code I tried below is way 
> >>slower than I think it ought to be.
> >>
> >>Does anyone have any suggestions (besides "write it in C")? Could _winreg 
> >>possibly be improved to provide an iterator or better interface to get the 
> >>subkeys? (or certain ones? There are a lot of keys under HKEY_CLASSES_ROOT, 
> >>and I only need the ones that start with a period).
> >
> >See this post I made some time ago:
> ><http://mail.python.org/pipermail/python-dev/2004-January/042198.html>
> >
> >>Should I file this as a feature request?
> >
> >If you still think it should be changed in the core, you should work on
> >a patch.
> >
> I could file a patch if no one else is looking at it. The solution would 
> be to use RegEnumKeyEx and remove RegQueryInfoKey. This loses
> compatability with win16 which I guess is ok.
> Garth

I would say it looks like no one else was looking at it, and Garth apparently 
didn't submit a patch. It's beyond my means to come up with a patch myself. 
Would someone be willing to take a look at it?

Sorry, but I really want access to registry subkeys to stop being so dog-slow. 

Thanks for taking a look,


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