On Fri, 1 Dec 2006 15:35:34 +0200, kgi <[EMAIL PROTECTED]> wrote:
Hi there.
I've got a web app that was originally written as a bunch of LiveElements at
the top level of a LivePage. I want to clean up this code and restructure it
such that several of the LiveElements are more modular; this entails making
some of the LiveElements contain other LiveElements.
Now, I could have *sworn* I've done this before, but whatever I try to do now
I get a nevow.errors.MissingRenderMethod exception.
At the end of this email is a cut-down example that exhibits the behaviour.
OuterWidget and InnerWidget are two LiveElement objects; they can both exist
happily in the LivePage, but if you uncomment the div containing an
innerWidget rendering directive (around line 28) you get:
File "/usr/lib/python2.4/site-packages/nevow/flat/ten.py", line 70,
in serialize
return partialflatten(context, obj)
File "/usr/lib/python2.4/site-packages/nevow/flat/ten.py", line 61,
in partialflatten
return flattener(obj, context)
File "/usr/lib/python2.4/site-packages/nevow/flat/flatstan.py", line
261, in DirectiveSerializer
renderer = rendererFactory.renderer(context, original.name)
File "/usr/lib/python2.4/site-packages/nevow/page.py", line 78, in
renderer
raise MissingRenderMethod(self, name)
nevow.errors.MissingRenderMethod: (<OuterWidget object at
0xb763482c>, 'innerWidget')
Can anyone shed any light on this?
There are also seemingly three styles for render methods that I've found. The
third was kind of guessed from the documentation of nevow.page.Element; I'm
not sure I've used it correctly, but I seem to recall reading that the
special "render_" prefixes will be going away and replaced by a renderer()
registration method, like the expose() method for athena callables.
All Element renderers _must_ use renderer(). All Fragment/Page renderers
_must_ use the "render_" prefix. All Athena callables _must_ use expose().
No other approach will work at all.
Which is the preferred form?
def render_innerWidget ( self, ctx, data ):
elem = InnerWidget()
elem.setFragmentParent ( self )
return elem
def render_innerWidget ( self, ctx, data ):
elem = InnerWidget()
elem.setFragmentParent ( self )
return ctx.tag[f]
Either of these is usable on a Fragment or Page class. Whether you wrap
the result in ctx.tag or not depends on whether you want to preserve the
tag on which the render directive was defined.
from nevow.page import renderer
def innerWidget ( self, request, tag ):
elem = InnerWidget()
elem.setFragmentParent ( self )
return elem
renderer(items)
Like the other examples, you could return ctx.tag[elem] here. The
difference between Fragment and Element or render_* and renderer() has
no bearing on that choice.
Hope this helps,
Jean-Paul
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