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Generating instances from schemas usually just produces one of the infinite number of instances restricted by certain trivial parameters. I don't know of an example where meaningful instances are generated. If a generated document changes automatically depending on the schema it finds at the time of generation yet somehow contains the same "information", there must be a model of the document that is independent of the schema, e.g., something like an ER model. Then the model must be populated: this concrete entity has that relationship to these other concrete entities, etc. Then there must be a mapping from the abstract document model to the elements and attributes used in the schema. When the schema changes, the mapping must change in concert (and there must be a way to prevent changes to the schema that violate the abstract document model, e.g., changing an unbounded relationship to a bounded one). After that, piece of cake. ;-} Bob Foster Bullard, Claude L (Len) wrote: > This one is fun. I know that a validating editor > can use a schema or DTD to create a valid file. > > Can a program do this for files it creates dynamically? > Are there examples of this? > > This question came from a programmer who doesn't want > to hardwire the structure of files she creates into > the code that creates them. I had replied with validation > on input (create the file, validate it then), and what > she actually wants to do is use the schema to drive > the file builder using say, SAX or its analog. Mainly, > she doesn't want to rewrite the code when new versions > of the document inevitably occurs. She just wants to > modify the schema. Works for editors but of course, > they run in human time, but other than performance, I > can't think of a reason WHY she couldn't do it. > > What about it? > > len
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