Cannot update zope.schema in Plone

Very new to setting up Plone 4 and trying to integrate Solgema.fullcalendar but when running buildout I get an error saying it needs zope.schema 3.6.0 and I have 3.5.4. I cannot for the life of me work out how to update it. I assume I am missing something fundamental here but it is doing my head in as I imagine开发者_Go百科 as I will encounter this kind of issue again and again as I progress.

" Installing instance. Error: There is a version conflict. We already have: zope.schema 3.5.4 but z3c.form 2.4.2 requires 'zope.schema>=3.6.0'."

Looked around and noticed that putting zope.schema>=3.6.0 in eggs might work but that didn't actually trigger an update just caused a bad install error.

If anyone has any ideas or needs something more to go on please let me know!

Thanks Chris

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If you want to use z3c.form inside Plone, best update to Plone 4.1 which is currently available as a release candidate. 4.1 comes with z3c.form in it and has the newer zope.schema version.

In the general case you will need to have a versions section in your buildout configuration in which you can specify exact version requirements for all distributions you want.

[buildout]
extends = ...

versions = versions

[versions]
zope.schema = 3.6.0

Inside the setup.py files you should never specify exact version requirements. Only put minimum requirements into these if your specific library absolutely requires a new feature from another library.

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See Hanno's answer. I will add that I cannot think of a good reason anymore to use '>=' (or '<=' or '==') to specify minimum, maximum or exact versions anywhere in a buildout config. Version specifications should only be in a [versions] section. It has been a while since I last used a buildout config that used the comparison operators, but I remember it could lead to problems, especially when upgrading; the only way out would at times be to remove the '.installed.cfg' file to make bin/buildout run in a fresh state.

(Note that '>=' in a setup.py is perfectly fine.)