Hi Martin. I can think of the benefits of viewlets in for Zope2 in
general, not just in Plone3 but the way they may integrate with CMF
particularly. These are good questions you are asking and hopefully
there will be a way to make this work sooner than later. I am very
interested in how cpsskins v3 will be fitting into the picture also.
The Z2 integration will be started soon at a sprint soon. Viewlets and
portlets seem pretty synonymous and cpsskins provides a way to
manipulate portlets visually which is very nice. The recent posts on
formlib integration with viewlets also has my interest since it should
make portlet development super easy as well. formlib by itself is pretty
sweet on its own. :-)
Martin Aspeli wrote:
Hi guys (sorry for the crosspost, this is rather a cross-area post),
I'm reading the docs for zope.contentprovider and zope.viewlet, and
there are many reasons why we'd like to use this in Plone. The way the
release cycles work, Plone 3.0 would be the natural place to put some of
this. Now, I have a few questions:
- In what version of Zope 3 did zope.contentprovider and zope.viewlet
appear? They're not in my Zope 2.9 lib/python/zope.
- Are they scheduled to be in Zope 2.10?
The main achilles heel as far as I can tell is the TALES 'provider:'
expression. I'm guessing that without using the Zope 3 ZPT and TALES
implementations, Zope 2 won't be able to use these.
- Is it the intention to use the Zope 3 ZPT and TALES engines in Zope
2.10? If not, are they scheduled for some other time? How much work is
needed for this to be a reality?
Now, I have a feeling that this could be faked in Zope 2 with something
<tal:block replace="structure python:provider('provider.name')" />
the object 'provider' would have to be defined globally (in
global_defines.pt in Plone). Its implementation would basically be
identical to the TALESProviderExpression in zope.contentprovider, with a
__call__() method that called update() and render() on an
IContentProvider looked up by the name it was passed.
The tricky part is the ITALNamespaceData update magic that needs to read
the TAL context:
- Is there some way a python object referred in an expression like the
one above could be passed or acquire (literally or figuratively) TAL
objects defined in the current context at that point?
- If not, based on your practical experience, how much is this used -
would zope.contentprovider and zope.viewlet be useless if Plone had to
say "we only support a subset of the zope.contentprovider API" (note: we
really don't want to do that, I'm just looking at options here)
The other problem with this implementation is that it would call
viewlets/content providers sequentially, i.e. call update(), then
render() for each object as it discovered them, not call all the
update()'s and then all the render()'s. I note that the
zope.contentprovider README.txt mentions that this is bad, but the
TALESProviderExpression implementation seems to suffer from exactly the
- Is this expected behaviour? Is it considered as "known issue"? Are
there plans to improve on this?
Thanks a lot!
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