[Zope-dev] Zope without Zope

[Chris McDonough]

On Nov 15, 2007, at 9:38 PM, Martin Aspeli wrote:

> Hi all,
>
> For fun, I just tried to make use of adapters and utilities,  
> registered with ZCML, in a Pylons application.
>
> I installed Pylons in a virtualenv, and easy_installed  
> zope.component and zope.interface using the KGS index for 3.4. I  
> used zope.configuration (also installed) to load a site.zcml, which  
> currently just has:
>
> 	<configure xmlns="http://namespaces.zope.org/zope">
>   		<include package="zope.component" file="meta.zcml" />
> 	</configure>
>
> That doesn't work - it complains about not finding zope.security.zcml.

No idea why this happens, sorry.

> Then I tried to easy_install zope.security, but this pulled in most  
> of Zope, including the ZODB, ZConfig and zdaemon. That's a real  
> shame - no CA (at least not with ZCML) without having pretty much  
> all of Zope there. :(

Yup.  Inappropriate dependency chain when you use the cheeseshop.  See http://mail.zope.org/pipermail/zope-dev/2007-November/030276.html 
  .

> Actually, I never got to try it further, because this then died with:
>
> Installed /Users/optilude/Development/Pylons/zylons/lib/python2.4/ 
> site-packages/ZConfig-2.5-py2.4.egg
> error: Installed distribution zope.traversing 3.4.0 conflicts with  
> requirement zope.traversing>=3.5.0a1.dev-r78730

If you're trying to installed these eggs using easy_install against  
the Cheeseshop, it won't work because the information in the setup.py  
of some eggs isn't the "whole story" about required versions of  
dependencies.  Instead, some of version pinning information is stored  
in buildout.cfg (in a [versions] section) within these eggs.  If you  
use buildout to install them, or use the KGS as the index URL to  
easy_install it will probably work.  See http://mail.zope.org/pipermail/zope-dev/2007-November/030279.html 
  (and actually the rest of that thread) for the whole story.

> Are the Zope eggs ready for prime time?

Not quite.  I've created a bot process which attempts to easy_install  
every distribution having to do with 'zope' from the cheeseshop into a  
clean virtualenv every few days.  I'm hoping this, along with regular  
prodding from folks like you, will keep us on the right track going  
forward.  See http://mail.zope.org/pipermail/zope-dev/2007-November/030271.html 
  to see an example of the result of the bot.

Currently we're still quite broken for people trying to easy_install  
most zope-related eggs other than zope.interface, zope.component, and  
ZODB from the Cheeseshop.  I asked for help fixing this the other day  
by asking if someone would remove a "bad" release from the Cheeseshop  
(I don't have the rights to do that) or by making new releases of eggs  
which pin versions in setup.py rather than in buildout.cfg (I don't  
feel qualified to do that, as I know little about the actual software  
and what impact that would have on people relying on the older  
version).  No one has done it yet, though, I suppose.

In the meantime, I've fixed one package (zope.tal) to remove  
inappropriate dependencies, but a new release hasn't yet been made  
from the changes I checked in.  Once it is, and it's been uploaded to  
the cheeseshop, you'll be able to install zope.pagetemplate without  
also getting ZODB and 74 other eggs. ;-)  But I'm sure other packages  
need to get fixed too (in particular, zope.i18n, where things really  
go pear-shaped).

> Maybe I should be doing it differently?

Please don't!  Just complain loudly. ;-)

> I'm curious about how to go about this, since it seems like an  
> incredibly useful thing to be able to do: Make use of the CA in a  
> non-Zope Python application. :)

In the short term, you should be able to do either of the following:

    - use buildout to install the eggs

    - use easy_install --index-url=http://download.zope.org/zope3.4  
<distribution>

The first one will work due to version-pinning statements in the  
buildout.cfg of dependent eggs.  The second one works because it  
doesn't find the "bad" distribution of zope.app.publisher that exists  
on the Cheeseshop that causes the later conflict.  You'll still get a  
bunch of eggs you don't need, but at least they'll get installed.

- C