On Fri, 22 Sep 2006 15:27:38 +0200, Markus Schiltknecht <[EMAIL PROTECTED]>
wrote:
Right. I try in nevow terms: I want to write a Page, which dynamically
displays different Fragments depending on the URL. I wanted to use all the
'locateChild()' mechanism for that, but this seems not possible.
Ok but this should be accomplished in a different way IMHO. You should have a
Fragments container somewhere and lookup stuff in there. It doesn't make too
much sense to have fragment children IMHO.
Since Pages are derived from Fragments, I didn't think about using Fragments
in the first place at all. (Of course, I'm 'using' Fragments, but hidden
from me through the Page class, which inherits from Fragments).
Well... Pages can be used in place of the Fragments but they will be considered
as Fragments with no extra functionality (even if the code is there) thus it's
better to stick with Fragments entirely for this usecase.
As you can see in my example, I've written my own 'locateFragmentChild()'
method which does exactly what I'm describing above.
Well but you just need to lookup stuff here and there, if you need to include
different fragments in a particular fragment then I guess this
locateFragmentChild is sort of useful although the name is not the best I can
think of, simply locateFragment should be enough (but as I can see there's
really no fixed hiararchy of Fragments and you shouldn't use the same mechanism
used in locateChild, I'd rather go with a dictionary containing all of them
because in the end that's what you are actually doing, including a fragment
depending on the url segment).
The use case is very simple and (IMHO) common: I have a top top level
template containing all the HTML headers and some common design elements.
Plus the top level navigation. Depending on the URL, different other
templates should be inserted (Fragments?). If you know Mason (perl) or
Myghty (python), I want to migrate from there. They have a structure like
that:
I have never used Myghty nor Mason but I do what you are describing everytime.
I use macros and Page objects with a small function that looks up the template
that should be included in the macro from an attribute value of the current
Page instance.
http://hg.stiq.it/stiq for some more code.
autohandler # the default template which gets
# rendered for every request
dhandler # a default handler, called if no child
# is given in the URL, i.e.:
# www.mysite.com/
foo.html # a normal site available at:
# www.mysite.com/foo.html
# it gets rendered as 'child' of the
# toplevel autohandler, thus it
# inherits it's methods and template.
foo/autohandler # the template for subdir 'foo' on:
# www.mysite.com/foo/*
foo/bar.html # a site in the subdirectory
# www.mysite.com/foo/bar.html
# For this, the toplevel autohandler is
# rendered first, then foo/autohandler
# and then foo/bar.html
I don't see a connection between this and the fragments though.
This is very usefull when writing 'hierarchical' sites, i.e. where you can
navigate in a tree. What's the best way to do that in nevow?
There are many different ways of doing it depending on the exact usecase.
Something else I'm very thankful about are the 'preprocessors'. It seems
they have (more or less) recently been added. Any chance I can pass them
arguments? Currently I simply insert a renderer in my preprocessor, but I'm
not sure if I can do everything with just inserting renderers (but probably
I can, I'll see).
Yes, they are a recent addition for a usecase in Quotient. You can pass
arguments by using closures of course. But inserting renderers is a strage
usecase, I've never needed it and pre-processors were added to change urls on
the fly (I think for caching purposes) when loading templates, not for changing
templates in that hard way. You might find some problems in doing that, but
I've never tried.
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