[Distutils] [buildout] extending a .cfg supplied by another package

Christian Zagrodnick cz at gocept.com
Fri Jul 30 14:44:28 CEST 2010


On 2010-07-30 10:17:09 +0200, Christian Zagrodnick said:

> On 2010-05-12 21:51:19 +0200, Jim Fulton said:
> 
>> On Wed, May 12, 2010 at 8:17 AM, Chris Withers <chris at simplistix.co.uk> wrote:
>>> Hi All,
> 
>>> I'd like to be able to do:
> 
>>> [buildout]
>>> extends=some.package:aconfig.cfg
> 
>> That's an interesting idea.
> 
>>> ...kinda like you can with templates in BFG, which I believe uses pkg_tools
>>> to do the hard work.
> 
>>> What're the chances of that happening?
> 
>> Low, in the short term. A good first step would be to work out a
>> somewhat detailed proposal including:
> 
>> - Descriptions of specific situations where this would solve a
>> problem, with specific examples of how the proposed meachanism would
>> be applied.
> 
>> - A syntax proposal.  It has to address distinguishing file paths from
>> urls from these new things. I suspect these should be expressed as
>> URLs, e.g.:
> 
>> project://some.project/aconfig.cfg
> 
> I propose egg://<requirement string>/<path in egg>.
> 
> For example egg://some.package=0.6/foo/file.cfg would basically return
> pkg_resources.resource_string('some.package', 'foo/file.cfg').
> 
> 
>> I'll note that I suspect you can do this now using a buildout
>> extension that installs a new URL handler in urtllib2.
> 
> That doesn't work for extends= because extends evaluated first to build
> the composed configuration. Extensions are loaded after that.
> 
> I don't see a useful way to not integrating the egg://-handler to
> buildout directly.
> 
> Are there chances this will integrated to buildout when we try that on
> a branch?

Actually I figured that an egg://-handler doesn't help with versions 
very much. I try something else and let you know when there is 
something interesting.

-- 
Christian Zagrodnick · cz at gocept.com
gocept gmbh & co. kg · forsterstraße 29 · 06112 halle (saale) · germany
http://gocept.com · tel +49 345 1229889 4 · fax +49 345 1229889 1
Zope and Plone consulting and development




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