[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Achieving object model independence
At 07:51 PM 11/18/2001 +0100, Bruno Dumon wrote: >Jim Wissner wrote: > >[snip] >>2. Create my own set of basic interfaces that mirror common object model >>components (Document, Element, Attribute), subclass the implementation >>classes of the corresponding dom4j/JDOM/DOM classes, set the appropriate >>factory methods to create instances of the subclasses that implement my >>common interfaces, and return those common interfaces to the rest of my >>library. >>I currently use this method with Xerces in order to implement undo/redo >>of DOM mutations, and it is quite effective. Nevertheless this approach >>makes me uneasy because it is dependent on utilizing "nonpublic" >>components (that is, having to subclass the default implementation >>classes which, though often public in the sense of Java scoping, are >>sometimes left out of documentation and presumably more subject to change >>than the rest of the APIs. Is this true, or am I being overly worrisome?) > >Not related to the original subject, but: > >To implement undo when using Xerces, you could as well use the DOM >mutation events, which Xerces supports. Just register event listeners on >the document node for all mutation events. Then it is easy to record all >changes so that they can be undone later. > >-- >Bruno Dumon > > Yes, thanks.. It's probably a better way to go as far as Xerces is concerned. I believe this is new in DOM Level 2. I don't remember it existing when I originally wrote the undo/redo mechanisms long, long ago. I'm reluctant to change to this event system, since of course not all object models implement DOM level 2. I'd really like to find a way to make these features available to my apps in a cross-object-model way. Care to comment on this original topic? Please? :) I'm still waiting for some great advice. Thanks, Jim -- www.jbrix.org Open Source Software Java - XML - Speech Recognition
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