[Distutils] Adding Provides-Extra as an edit to PEP 345

[Éric Araujo]

Hi,

> Hopefully this will be a more useful spec.
Thanks for the proposal, but it is not really a spec.  You’re suggesting 
name and syntax for a new field, but you don’t describe what it means 
and what it is used for.  From what I understand, the goal is similar to 
build dependencies and optional dependencies in systems like Debian’s 
dpkg; for the build dependencies, there were multiple threads about 
adding Setup-Requires-Dist (like setuptools’ setup_requires) and 
Test-Requires-Dist (like tests_require, or whatever the spelling is—I 
always get it wrong :), for which we were near to agreement.  See 
https://groups.google.com/forum/?fromgroups#!searchin/the-fellowship-of-the-packaging/setup-requires/the-fellowship-of-the-packaging/KVsDQawfEno/M-ODKx9Ne5YJ 
and 
https://groups.google.com/forum/?fromgroups#!searchin/the-fellowship-of-the-packaging/setup-requires/the-fellowship-of-the-packaging/yTsRLtl6eoE/fVGb4t2zm68J

> This begs for parenthesis in environment markers, something that is
> easy to do by compiling markers to Python functions using the ast as
> `markerlib` does.
distutils2 supports Python 2.5, which has _ast but not ast IIRC.  If you 
have other suggestions for improvements like this please open bug 
reports though!  Feedback and patches are welcome.

Regards