Martin Cooper wrote:


On 11/26/05, *Frank W. Zammetti* <[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>> wrote:

    Craig McClanahan wrote:
     > If you're using JavaScript, why would you restrict yourself to that
     > (even if you *could* figure it out)?  You can dynamically
    add  fields to
     > a JavaScript object, so an analog of the set properties rule
    would just
     > define a field on the object for every attribute in the XML element.

    That's a good point... that thinking leads to a path where instead of
    populating pre-made objects from a parsed XML document, the objects
    themselves are created on-the-fly.  Or more precisely, you wouldn't have
    to deal in pre-defefined objects.


At that point, you've just reduced the problem to parsing XML in JavaScript, which is a solved problem. ;-)

Haha, in a way, yeah :)

It's more the event-oriented model of Digester though that I don't think there's an analogy for yet in Javascript... not without knowing something about the DOM structure before-hand anyway.

Putting the conversion in the setter would be unfortunate, since you've then embedded knowledge in that setter that would have otherwise been confined to the Digester rules.

I would agree if we were talking about a 1:1 conversion of Digester... but as Craig previously pointed out, it's probably not possible, or even desireable, to try to do a 1:1 conversion. One could make the argument with normal Digester that things would be a lot simpler if all you ever had was setXXX(Object), and the object itself took care of type conversions as it probably knows what it needs better than Digester does... in Javascript you almost have no choice but to think of it that way :)

Note that ObjectCreateRule is going to be, um, "interesting", for a couple of reasons. Probably the trickiest thing is going to be finding the class that you need to instantiate, since you won't have Java's class loading mechanisms to help you out.

Excellent point. It might be enough to simply state that any class to be instantiated by Digester has to be available in page-scope before the parse() method is called, and leave it at that. The developer will have to include the correct import or include or whatever they do. But this is clearly something that needs to be thought through.

> You're going to need to
implement some kind of dynamic loading scheme, and the classes you instantiate are going to have to play by the rules you define for that. (BTW, Dojo has one you could use. ;)

Yep, that's one answer, and seeing what Dojo offers would be a good idea in that case.

> Also, many uses of (Java) Digester
take advantage of zero-arg constructors, a la JavaBeans, but most classes in JavaScript don't have such things, so you'll need to be passing in parameters to those constructors.

But, IIRC, that is a requirement of the spec, right? So, if there is a basic assumption that any class Digester will work with follows the spec, that should take care of it.

Just a couple of thoughts off the top of my head.

Yeah, it'll definitely be an interesting road :) I probably won't try and start until Monday, but I'm actually looking forward to seeing what I can put together next week.

Frank

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