[Zope] Why is index_html() called instead of __call__()?

[Kyler Laird]

Brian wrote:

> ZPublisher looks first for index_html, and will only use __call__ 
> if it doesn't find an index_html on the published object.

Looking at ZPublisher/BaseRequest.py, I'm starting to understand.

> Note 
> that the index_html may be acquired from a containing object, so 
> an object that always wants to control its own rendering should 
> define its own index_html to prevent that.

Further, this is the *only* way to do it.  As I've noticed recently,
any attempts to delete index_html in the root folder will result in
recreation at the next upgrade (for Debian at least).  Because there
will always be an index_html in the heirarchy, there is no way to
affect behavior by defining __call__.

Because there is no hook before index_html, is is impossible to
(cleanly) make an object that renders itself sometimes, and allows
index_html to do it at other times.

> It sounds like the 
> PropertyFolder implementation might want to do something like:
> 
> class PropertyFolder(...):
>   def __call__(...):
>       ...
> 
>         # alias to be sure we always control our rendering
> 	  index_html = __call__

This would result in never being able to call the index_html in the
ZODB.

--kyler