[Distutils] PEP-426 environment markers [was: Re: Support for condition to include or exclude a buildout sections based on a Python expression]

[Jim Fulton]

On Wed, Jan 30, 2013 at 9:46 AM, Daniel Holth <dholth at gmail.com> wrote:
> My markerlib implements the PEP. https://bitbucket.org/dholth/markerlib
>
> The parsing is simpler than you might expect. There is no monkey patching.
>
> It is a (non-API) part of distribute since about last August.

But we're not implementing the PEP. The PEP is only tangentially
related to this use case.  I'd be happy to be PEP informed, but not if
it makes things awkward.

It's much easier to say "these are python expressions with the
following variables available" than to say "you can use the
expressions described in PEP 426 plus additional variables", where,
BTW, you can't say ``not windows``, which is probably one of the 2
most common expressions you'd want to use.  Note that many or most
buildout users would have no reason to be familiar with the PEP.

This isn't a criticism of the PEP. The PEP was developed for
some use case that's different than this one.  Well, I'm guessing
because the PEP doesn't actually state the problems it's addressing.

Jim

-- 
Jim Fulton
http://www.linkedin.com/in/jimfulton
Jerky is better than bacon! http://zo.pe/Kqm