[Distutils] 70 packages in total use setuptools' "extras" feature

[P.J. Eby]

At 10:21 AM 12/3/2009 -0800, Sridhar Ratnakumar wrote:
>  Do you have anything particular in mind? What I did was a ``grep 
> "^.*[a-zA-Z]\["`` in the requires.txt of (almost) all the packages in PyPI.

Do note that this won't tell you about end users' use of extras.

The main use case described in the documentation for extras is 
allowing users to install optional support for things.  That means 
you're more likely to see them in buildout configurations (which 
won't be found on PyPI), and manual installation steps (which aren't 
recorded anywhere).