[Grok-dev] Re: zc.sourcefactory

[Philipp von Weitershausen]

On 3 Sep 2007, at 11:20 , Jan Ulrich Hasecke wrote:
> Am 03.09.2007 um 10:26 schrieb Philipp von Weitershausen:
>
>> On 3 Sep 2007, at 10:22 , Jan Ulrich Hasecke wrote:
>>>
>>> Is zc.sourcefactory a default part of grok?
>>
>> Nope.
>>
>>> I get an ImportError.
>>>     ImportError: No module named sourcefactory.basic
>>>
>>> If it is not installed by default, how do I install it? Are there  
>>> any howtos?
>>
>> There aren't, but it'd be cool if someone could write one down.
>>
>>
>> Basically, by importing zc.sourcefactory in your code, you  
>> introduce a *dependency*. Dependencies are managed in setup.py. So  
>> edit setup.py and add 'zc.sourcefactory' to the install_requires  
>> list. Then run bin/buildout again. It will download and install  
>> zc.sourcefactory now.
>>
>> This is, by the way, how all of the Zope packages are installed  
>> automatically. Your package depends on 'grok' and 'grok' depends  
>> on various 'zope.*' packages. buildout simply makes sure that all  
>> the dependencies are installed.
>>
>
> I would write a howto, but first of all I plead to call buildout sid.
>
> I get this error while calling buildout in my grokproject:
>
> Error: There is a version conflict.
> We already have: ZODB3 3.9.0-dev-r77011
> but grok 0.10 requires 'ZODB3==3.8.0b2'.

Hrmpf. Now I know why I objected to fixed version dependencies in  
grok/setup.py.

Anyway, setuptools's and zc.buildout's version dependency mechanism  
is rather, uhm, dull. It wants to install zc.sourcefactory which  
depends on ZODB3. So it tries to get the newest ZODB3 possible. Then  
it wants to install grok which depends on a very specific ZODB3  
version (3.8.0b2).

A workaround is to tell buildout to only ever chose one particular  
ZODB3 version. Add the following section to your buildout.cfg::

   [versions]
   ZODB3 = 3.8.0b2

And in the [buildout] section, refer to it::

   [buildout]
   ...
   versions = versions

Then run bin/buildout again. It shouldn't break now (I've tested it).