[Zope-dev] Re: RFC: Eggifying Zope's extension mechanism ("Products")

whit d.w.morriss at gmail.com
Mon Jan 29 19:24:53 EST 2007

Philipp von Weitershausen wrote:
> Rocky Burt wrote:
>> On Thu, 2007-25-01 at 05:07 -0800, Martin Aspeli wrote:
>>> I do wonder what would happen if you had both 
>>> lib/python/Products/CMFCore
>>> and Products/CMFCore, though. Would there be an explicit preference 
>>> or would
>>> Zope fail to start up with a conflict? I think I'd prefer the latter, in
>>> fact, so that people don't end up modifying/upgrading the wrong code by
>>> accident!
>> Well, we could probably add conflict-detection to the entry point
>> handlers for Zope (ie so any two packages that try to register as the
>> same project would cause an error).  But regarding Products/CMFCore and
>> lib/python/Products/CMFCore conflicting... that would be up to the
>> standard pythonpath mechanism of the python interpreter (whichever is
>> first on the path wins).
> Zope 2 itself manipulates Products.__path__ to add INSTANCE/Products (or 
> any other directory specified in zope.conf) as a directory which can 
> contain further products (the original Products package lives at 
> ZOPE/lib/python/Products). pkg_resources uses the same mechanism for 
> namespace packages (that's what the 
> pkg_resources.declare_namespace('Products') call is all about); it 
> appends to __path__.
> Therefore, Zope will treat /path/to/the/CMFCore-egg/Products as another 
> directory that contains a product (in this case just one, CMFCore). Thus 
> the standard product override rules apply when the same product is 
> installed in multiple directories.
> I updated the proposal text with this information.

I imagine it would be pretty trivial to write something that would 
generate a setup.py from an svn:externals property so you could create a 
"Products" distribution in one fell swoop, especially since the entry 
point section of the setup.py can handle config parser output.



------ d. whit morriss ------
- senior engineer, opencore -
- http://www.openplans.org  -
- m: 415-710-8975           -

"If you don't know where you are,
  you don't know anything at all" 

Dr. Edgar Spencer, Ph.D., 1995

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