Unfortunately XQuery has neither higher-order functions nor 
dynamic evaluation. (With higher-order functions, the variable doesn't hold the 
name of the function as a string, it holds a reference to the function as a 
first class object). However, many implementations do have an eval() function 
(in saxon it's called saxon:evaluate()) and some (including Saxon-SA) also have 
a capability for higher-order functions.
 
If you're prepared to consider XSLT rather than XQuery, 
Dimitre Novatchev's FXSL library provides a full implementation of higher-order 
programming in 100% portable XSLT code (this is possible in XSLT because it can 
ride on the dynamic despatch mechanism offered by 
xsl:apply-templates).
 
Michael Kay
http://www.saxonica.com/


  
  
  From: Ignacio Tripodi 
  [mailto:ignaciot@g...] 
Sent: 08 August 2008 
  19:54
To: xml-dev@l...
Subject: [xml-dev] Dynamic 
  function names


  
  Is this possible to do with XQuery? I'd like to be able to eval() 
  a function whose name I'm getting from a variable. In a nutshell, I would have 
  an attribute whose value is the function name that needs to be called. 
  Something 
  like:

                
  let $func_name := 
  //blah[@function_to_run]
                
  let $func_argument := 
  //blah[@some_id]
                
  let $result := eval($func_name( $att_value ))

which would basically 
  execute the function whose name is $func_name, passing it $func_argument as 
  the only argument and storing the result in $result. Of course, the 3rd line 
  does not work and it's only to show what I'm trying to accomplish. Is there 
  any way to accomplish this, not necessarily using eval()?

Any help will 
  be greatly appreciated!

-i