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[XQuery Talk Mailing List Archive Home] [By Date] [By Thread] [By Subject] [By Author] [Recent Entries] [Reply To This Message] Global variables in XQueryMichael Kay mhk at mhk.me.ukThu Oct 5 12:52:15 PDT 2006
> Nevertheless, there are > many occasions in which a programmer needs to both read and > write a global variable, especially when recursive functions > are involved. For instance, suppose I want to know the number > of recursive calls of my recursive function (this number is > an lower bound of the space complexity of the function). This kind of use-case - producing a secondary result that's essentially diagnostic or instrumentation output - was what motivated me to add saxon:assign to my XSLT processor, a decision I have bitterly regretted because it gets abused by people who just use it to write pure procedural code which has a nasty habit of breaking under optimization. In the light of this experience I think the proposal currently on the table to add procedural extensions to XQuery (mentioned by Jonathan) is probably a bad idea. I think it's much better to use a procedural pipeline language [1] to string together non-procedural components to assemble an application. The right way to implement a counter for instrumentation purposes is probably by calling an extension function. [1] http://www.w3.org/TR/xproc/ Michael Kay http://www.saxonica.com/
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