Using views as information mixins in templates

zope2, zope3, cookbook

This may be basic trick for some, a non-obvious usage of views for others, who knows, I'm documenting it here anyway. I've been using this technique for quite some time without giving it much thought.

There are times when I have an object in a template. I want to display information associated with that object. This information is already coded in a @@detail view on this object. Suppose this example (in mostly pseudocode):

class PersonDetail(BrowserView):
    """Show detail about a person"""
    def name(self):
        return compute_somehow_name()

class CommentDetail(BrowserView):
    """Show details about a comment"""

Now we have the following template for the CommentDetail view:

<div tal:define='person comment/author; person_info nocall:person/@@detail'>
    <a tal:attributes="href person/@@absolute_url" tal:content="person_info/name">The author</a>
</div>

Notice the nocall: keyword placed in from of the person/@@detail call. This ensures that the @@detail view is instantiated, but not called (so it is not rendered). This way we have access to the view class attributes, properly associated to the Person context.