[XML-SIG] DOM Considered Harmful :-)
Wed, 05 May 1999 17:11:18 -0400
Greg Stein wrote:
> On Wed, 5 May 1999, Jim Fulton wrote:
> > > I'm tremendously in favor of the model returned by qp_xml.
> > (BTW, could you provide a link to this proposal?
> > I must have deleted the message that contained it. I'd
> > like to look at it.)
> It's available from my page at: http://www.lyra.org/greg/
Thanks, I'll take a look.
> > Acquisition has worked very well in Zope. It provides a
> > very nice way to share information in a containment hierarchy.
> > It's only drawback is that it requires use of ExtensionClass,
> > which is actually a bonus. ;)
> Is that still a patch to the interpreter, or is it all Python code now?
It never was a patch. It *is* an extension module. There's an ExtensionClass
extension module and an Acquisition axtension module, which requires
the ExtensionClass extension to be around.
> I'd be interested to see what kinds of changes would be needed to use the
> acquisition stuff.
Basically, you subclass one of the acquisition base classes
(Explicit or Implict) and then, when you want to refer to a parent
in a child (that has been accesses through a parent), you refer
to the parent via the attribute, aq_parent.
Given that in DOM (if my vague recollection serves me :) children are
not accessed as attributes, the access methods need to return the children
on the context of the parent, as in:
def some_method_that_returns_a_child(self, ... whatever):
The special method __of__, which comes from a mix-in class
returns one object "in the context of" another.
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