[xquery-talk] Setting global variables

Ronald Bourret rpbourret at rpbourret.com
Tue Oct 30 21:55:23 PST 2007

Is there any way to set a global variable from inside a function? (By 
"global variable", I mean a variable declared in the prolog of a 
function library.)

Basically, I'd like to read a document and save a subset of the document 
in a global variable, then refer to it later when doing lookups. For 
example, I'd like to do something like the following:

    declare variable $foo:listOfNames external;

    declare function foo:firstFunctionCalled(...)
       let $foo:listOfNames := fn:doc("mydoc.xml")//Name

    declare function foo:functionCalledMuchLater(...)
       if ($name = $foo:listOfNames)

Currently, I pass such information from function to function until it is 
finally used. While this works (and some would argue is the correct 
style), it has the following drawbacks:

1) It is difficult to follow the information through the chain of functions.

2) It can be confusing to read the intermediate functions, as these 
never really use the information.

3) It is brittle when refactoring the intermediate functions. Because 
the information is not really used -- it's just passed along -- it is 
easy to accidentally drop.


-- Ron

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