[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: RFC: Simple XML Event-Based API for Java
Don Park wrote: > >I don't see the point of the XmlProcessor first argument. What's wrong > >with having the implementation of XmlApplication store the XmlProcessor > >in the member variable? (This is what SP typically does.) > > XmlApplication can not store the XmlProcessor in the member variable because > it is an interface. I am very happy to see that XmlProcessor and > XmlApplication are interfaces rather than classes. I didn't suggest XmlApplication should should store XmlProcessor in a member variable. I suggested that implementations of XmlApplication could (if they needed to make callbacks to XmlProcessor) store XmlProcessor in a member variable. > >I don't think this is a good idea. It adds complexity and it's likely > >to impose a performance cost, but it doesn't buy you anything, because > >you can achieve that functionality with a MultipleXmlApplication class > >that implements the XmlApplication interface, and provides > >addApplication and removeApplication methods, and then forwards each > >event to the applications that have been added to it. > > Support of multiple event listeners is the norm in the Java world. As they > say "When in Texas, wear cowboy boots". I don't think it's appropriate to carry over patterns from GUI events and apply them to XML events just because we happen to use the word "event" to describe them both. I believe performance is important for XML processing, and an interface shouldn't impose an unnecessary performance cost. The real merit of this interface is that it's simple; unless there's a really compelling need for a feature, I think it should be left out. > If we were really concerned about performance, I > would recommend giving up the use of String. It's (rightly in my view) done that already for character data (which I think is right). It's not a problem for element type names, because an implementation can maintain a hash table of names and thus only allocate a String for each distinct element type. > >> userData property also gives users a chance to pass extra information > >> to the processor easily, if they wish. > > >Surely there are cleaner ways to do this sort of thing. > > I do not think so. Just as every Mac developer loved having RefCon to hang > thing onto, I like userData. Could you explain a typical case where you need this? Are there any standard Java classes that do this? It feels very wrong to me; it's the sort of thing I would try hard to avoid in my own programming, but maybe this is my strongly-typed C++ prejudices showing through. To me it seems like a feature that one can easily manage without. James xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i... Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ To (un)subscribe, mailto:majordomo@i... the following message; (un)subscribe xml-dev To subscribe to the digests, mailto:majordomo@i... the following message; subscribe xml-dev-digest List coordinator, Henry Rzepa (mailto:rzepa@i...)
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