From: Trans <transfire@...>
Date: 2007-11-27T09:07:40+09:00
Subject: Re: How to map XML attributes



On Nov 26, 3:25 pm, Phrogz <phr...@mac.com> wrote:
> On Nov 26, 9:37 am, Trans <transf...@gmail.com> wrote:
>
>
>
> > I'm working on a DSL that maps XML <=> Object, and I'm stuck on where
> > to store tag attributes. Do attributes belong to the tag or to the
> > content?
>
> > For example:
>
> >   <foo>
> >     <bar xmlns="http://..." type="html">
> >        HTML Content
> >     </bar>
> >   </foo>
>
> > In mapping this to an object, lets say:
>
> >   foo.bar  #=> "HTML Content"
>
> > Does is make sense to ask:
>
> >   foo.bar.attributes  #=> { 'xmlns'=>..., 'type'=>... }
>
> > or should the attributes be tied to the "attributation" of foo, so:
>
> >   foo.attributes(:bar)  #=> { 'xmlns'=>..., 'type'=>... }
>
> > The 'type' attribute makes me think the first makes the most sense,
> > but the 'xmlns' makes me think the later.
>
> I don't share your opinion on xmlns implying the latter. All
> attributes are attributes of an element; the first totally makes
> sense.
>
> How would you get the attributes of the rootmost element, e.g.:
>   <root id="page3">
>     ...
>   </root>
> Just attributes( :root )? Bleah, I say.
>
> If I were writing an XML-like DOM, I'd use dot notation (method call)
> for the child axis and [] notation for the attributes axis.
>   foo.bar[:type] #=> ...

Thanks guys,

I've taken your advice(s).

The reason I thought maybe to do it otherwise is b/c of a basic coding
principle --eg. the object referenced by an instance var doesn't know
the instance var's name. In mapping XML elements to Ruby objects I
felt like I was violating that principle if I carried the name along
with the element's body, and subsequently the attributes too.

I think I have a suitable compromise though. I attached the name and
attributes to an "Element" object which delegates via method_missing
to the underlying body object --which itself has no idea what the name
and attributes are.

Make sense?

T.