[Zope-CMF] [dev] 'add' actions and views - a proposal

Wichert Akkerman wichert at wiggy.net
Sun Sep 21 11:20:41 EDT 2008

Previously Martin Aspeli wrote:
> Wichert Akkerman wrote:
> > Previously Martin Aspeli wrote:
> >> Hi Yuppie,
> >>
> >>>>> 1.) CMF add views adapt not only container and request, but also the 
> >>>>> type info object. This way the views can't be accessed directly and have 
> >>>>> self.fti available.
> >>>> This is quite interesting, and possibly necessary. However, it means 
> >>>> that CMF add views are not just "views" and will need to be registered 
> >>>> differently to other views (i.e. you can't just use <browser:page /> 
> >>>> which also means that you won't get the Five security treatment etc).
> >>> Yes. This causes more problems than it solves. I think I found a much 
> >>> better solution:
> >>>
> >>> CMF add views are registered for a special layer called IAddViewLayer. 
> >>> Like any other layer, IAddViewLayer extends IBrowserRequest. And it 
> >>> defines an additional 'ti' attribute for the request.
> >>>
> >>> Like before views can't be accessed directly and have self.ti available. 
> >>> (I now use 'ti' instead of 'fti' because we have other type info 
> >>> implementations than FactoryTypeInformation.)
> >> I'm not sure I like this much more. It involves adding a marker 
> >> interface to the request conditionally during traversal. You'll possibly 
> >> run into funny sequence dependent conditions if you want to customise 
> >> the add view for a particular "theme" browser layer.
> >>
> >> My preference would be:
> >>
> >>   - Define an interface IFTIAwareView that has an 'fti' property
> >>   - Define a traversal view (@@add) that does this kind of thing on 
> >> traversal:
> > 
> > Why not a ++add++ traverser? Aren't traversed supposed to be used for
> > that kind of thing? Or does a view gives us something here that a
> > traverser doesn't?
> Namespace traversal adapters are similar to IPublishTraverse solutions. 
> The difference is that the namespace traversal adapter normally returns 
> something "containerish" from which traversal continues. I think it's 
> intended mostly as a "redirect" to a different traversal namespace, e.g. 
> in the way that plone.app.portlets has namespaces for portlet managers.

The containerish thing is just a lookup-mechanism, which could be a very
simple thing to figure out the right add view, which shouldn't be
more than half a dozen lines of code. It feels like a perfect fit to


Wichert Akkerman <wichert at wiggy.net>    It is simple to make things.
http://www.wiggy.net/                   It is hard to make things simple.

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