On Fri, Oct 08, 2004 at 06:26:51PM +0200, Lars Gullik Bjønnes wrote: > John Weiss <[EMAIL PROTECTED]> writes: > > | The DTD for an XML format (or, if you prefer, the XSchema for an XML > | format) is like the header file for a C++ class. A file with "an XML > | look" is the *implementation* of an instance of a C++ class. > > I don't really agree with this analogy.
Nevertheless, it's what I've had direct experience with in the field, on projects in the workplace. > | "Playing around with the XML look" is far, far, FAR easier to do from > | within a DTD. > > Is it really? Oh G*d yes! Projects that try to reverse-define the DTD later fail spectacularly. There's always something absolutely critical that the parser implementation missed, requiring heavy rewriting. Now, there's also the other extreme: pure, abstract, ivory-tower definitions of a DTD whose requirements make the parser & code implementation unworkable. I am *not* advocating that! :) We want the happy-medium: a DTD suggested by a pre-existing parser implementation, but designed for the future. ;) I come back to something I said in a different post: Creating XML formats requires a different way of thinking than designing OO-code. Here's a question for everyone reading: Ever worked with SQL? When I first learned SQL, I had my brain stuck in C++-programmer-mode. Remember how you had to keep reminding yourself, "Use JOIN's; there are no for-loops. Use JOIN's; there are no for-loops...." Me too. Well, XML formats are yet another paradigm-shift. They require different thinking than other sorts-o-coding. Lastly, moving to an XML-format for LyX gives us an excuse to make some potentially long-overdue changes to the LyX core data structures. Lars, I *know* all of those enums that fire off different functions via switch-statements *must* make your skin crawl everytime you see them. I'm sure you have whole blocks-o-code you'd like to refactor into abstract classes. Thinking about the format ... since it's such a big change, anyhow ... gives us permission to make those changes/cleanups. But, it doesn't require them. :) -- John Weiss
