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Re: sXBL issue -- bindings getting notified when the bound element is inserted into a document

From: Boris Zbarsky <bzbarsky@mit.edu>
Date: Tue, 22 Mar 2005 18:08:33 -0600
Message-ID: <4240B381.8090306@mit.edu>
To: Jon Ferraiolo <jon.ferraiolo@adobe.com>, www-svg@w3.org

Jon Ferraiolo wrote:
> (1) Boris seems to be saying that in XBL2 a bound element will have 
> different methods depending on whether it has been inserted into the 
> document or not.

No.  I am saying that I hope this does NOT end up the case.  I am also saying 
that this IS the case in Mozilla XBL in some cases, and that this causes a fair 
amount of grief.

Further, I am saying that the best way to prevent this problem cropping up in 
XBL2 is to consider binding attachment now, before it becomes effectively set in 
stone by sXBL.

> I agree that it is likely that somehow or other XBL2 will allow bindings 
> to define methods and DOM attributes for bound elements. Under that 
> assumption, thinking ahead to XBL2, doesn't it make sense that these 
> APIs would be available at the time the xbl:bound event is raised, no 
> matter whether the bound element is inserted into the document or not?

Yes, agreed.  I have been operating on the assumption that this is the case.

I am also operating on the assumption that people will want to use XBL2 to 
create reusable bindings, which other developers will then use in their pages. 
If this is not the case, then never mind me.

> (2) I still don't understand why the binding can't just register a 
> DOMNodeInsertedIntoDocument listener on the bound element. I apologize 
> for my inability to follow the discussion fully. Is it because 
> DOMNodeInsertedIntoDocument results in common scenarios where the node 
> might not be in the document anymore, which causes a large percentage of 
> developers to have to put in a lot of checks into their scripting logic? 

I would not call the scenarios common.  But they're not particularly rare either 
(there are certainly HTML pages out there that have <script> nodes that remove 
themselves from the DOM, or tear down the entire DOM, when they execute, which 
is more or less the same idea).  And if we accept my premise that people are 
trying to create reusable bindings, then they need to operate in a wide range of 
environments, which means they need to deal with this issue.

> Boris described a case where a binding is added at the same time that 
> script is removing a node.

No.  I described a case where the insertion of a node fires events or scripts 
that remove it.

> Is this a common case?

Again, it happens....

> I am wondering if we can at least warn developers about processing model complexities and 
> suggest some techniques to avoid these complexities.

You may want to view my suggestion as a proposal to simplify the processing 
model so that developers need not deal with quite as much complexity.

-Boris
Received on Wednesday, 23 March 2005 00:22:15 GMT

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