Saxon

Legacy ID: #4897073 Legacy Poster: Michael Kay (mhkay)

I can't say I'm very keen on the XPath VariableResolver mechanism. It's main fault is that it only binds variable references at run-time, which means there's very little you can do at compile time - you don't even know whether the variable exists, let alone what type it is. I'm not 100% against allowing XQuery variables to be declared programmatically, in the way that namespaces are, by means of a declareVariable() call on the StaticQueryContext object; but I don't think that meets your requirement, which is to avoid declaring variables at all. Frankly, I'm not convinced that's a good idea. It's certainly not high up my priority list of good ideas. The XPath interfaces allow you to do something similar with namespaces, by providing a namespace resolver in the static context object, and it has proved quite troublesome, mainly because there are interfaces that need to know what all the in-scope namespaces are; I think the same problems would occur with variables (for example, consider a debugger). Michael Kay

Legacy ID: #4897729 Legacy Poster: David Lee (daldei)

I appreciate the issues you raise. What I was hoping for is a change which would likely make things better for this one use case but worse for a lot of others. Clearly not a great idea ! I would still suggest considering, as you mention, exposing a programatic way to do "declareVariable" on the static query context. This would atleast avoid the parsing overhead of having to generate as text, then pasrse as text a bunch of "declare variable $x external;" statements. Is there a way to inspect a query after its compiled but before its run to determine which variables were actually referenced ? And if so, is it possible to make it a non-error to not set the values of external variables which were not used ? This would make it possible to declare say 100 variables, of which the script might use 2 or 3, then only set those values. I'm also looking at alternatives at the scripting layer (outside the calls to saxon) where I can get information prior to constructing the query on which variables absolutely need to be exposed as xquery variables. Thanks for thinking about this and responding ! -David Lee dlee@calldei.com http://www.xmlsh.org

Legacy ID: #4901140 Legacy Poster: Michael Kay (mhkay)

>I would still suggest considering, as you mention, exposing a programatic way to do "declareVariable" on the static query context. Yes, I'll consider that. >Is there a way to inspect a query after its compiled but before its run to determine which variables were actually referenced ? Run the explain() method on the XQueryExpression, using an ExpressionPresenter that subclasses the standard ExpressionPresenter, intercepting calls on startElement and emitAttribute to recognize a variableReference element and its name attribute. However, this will also give you references to variables that are locally declared within the query. >is it possible to make it a non-error to not set the values of external variables which were not used ? Use "declare option saxon:default" described at http://www.saxonica.com/documentation/using-xquery/extensions.html Michael Kay