On Sep 3, 2007, at 4:13 PM, Philipp von Weitershausen wrote:

Wichert Akkerman wrote:
The only problem is that distributing grok-0.11.cfg is a bit tedious. How about if buildout could get it from the web?
How about making it available from an egg, through a hook in egg-info

This is a very good point. So good in fact that I thought of it myself :) I was already writing the email when your message came in.

Martijn and I discussed the known working set problem over IRC this afternoon. He brought up a few good points which suggest that the version data could be associated with the egg:

The approach that I described in my original posting (and which actually works *today*, as I found out!) has some disadvantages. For instance, the discoverability and release mechanism of the known working set configuration file differs a lot from our normal packages. Releasing a package is a well-known routine by now. How and where would we release the working set configuration file? SVN?

Another problem are dependencies and how we'd like to depend on other working sets. Let's say we made a 'Zope' working set that contained the stable versions of the zope.* packages. It would make sense for grok to depend on this information. And packages using grok should depend on that. It'll be complicated to maintain such a chain in separate text files, especially across version updates. It only seems natural to use the egg dependency mechanism for this.

So, a possible solution is to associate the known working version info with an egg. More to the point, an egg could -- in addition to simply listing the names of its dependencies -- also specify which versions of those eggs it works best with. Wichert and I suggest that this could be put in a file in the EGG-INFO directory.

The only problem is that we usually don't version control egg-info directories. That means the information needs to be contained or at least referenced in setup.py and then written upon "setup.py egg_info". Here's what setup.py *could* look like::

  known_working_versions = {
    'ZODB3': '3.8.0',
    'zope.component': 3.4.0,


When EGG-INFO is written, a custom writer will then take this information and generate 'known_working_versions.txt' or whatever in EGG-INFO. The only problem is that this custom writer needs to be installed when setup.py is called to create egg, in other words to generate the right kind of eggs you'd need to have something installed first. Not sure if this is better than maintaining .egg- info directories in SVN...

How would the "known_working_versions" be used? You haven't specified that. Presumably this would be something that is overridable. How would this be overridden?

I'm very much against making setuptools *more* complicated than it already is.

Perhaps buildout (and setuptools) should grow a mechanism for being able to override/resolve version conflicts.


Jim Fulton                      mailto:[EMAIL PROTECTED]                Python 
CTO                             (540) 361-1714                  
Zope Corporation        http://www.zope.com             http://www.zope.org

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