[Twisted-Python] Twisted.web/DOMTemplate

Stephen Thorne sjthorne at ozemail.com.au
Sat Aug 10 08:54:26 EDT 2002

Hash: SHA1

Okay, I've been doing some hacking trying to make a small application using 
twisted.web and the .rpy stuff, using DOMTemplate.

Ordinarily I'd chat about something like this on the irc channel, but it was 
dead quiet. Apart from me talking to myself of course.

in the template:
<P view='getBody'>

in the response object
    def factory_getBody(self, request, node):
        print 1
        return node

This (when twistd --nodaemon is used) prints 1 twice (instead of the once 

This is because of the following section of code:
    def getNodeView(self, request, node):
                    maybeWidget = viewMethod(request, node)
                    if isinstance(maybeWidget, domwidgets.Widget):
                        view = maybeWidget
                        viewMethod = view.generateDOM

This is *bad*. viewMethod in this instance is response.factory_getBody, and in 
order to figure out if factory_getBody returns a widget as opposed to an 
instance of xml.dom.minidom.Element it actually calls the function to have a 
look. If it doesn't return a widget it *throws the result away*. viewMethod 
is then returned and used elsewhere, where its actually intended to be used.

Considering that rendering a template node could have program logic in it that 
only should be evaluated once per pageview. It could also carry some 
expensive database transactions.

Anyhow. I can't figure out how to refactor without breaking Widget 
functionality, and the way 'controller' works.

Anyhow. I think I'd call the above a bug report. Maybe with elements of rant 
thrown in.

Stephen Thorne.
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