[xsl] how to efficiently extract unique list of URI's for writing files

Hi all,

Again the data is completely made up but is easy to explain what I'm trying to 
accomplish.  In below input I have a sequence of objects. Each needs to be 
written to some URI.

e.g.
/objects/crontask/SyncDB.xml
/objects/user/12345.xml

The problem is that the input may contain duplicate entries (not deep-equal 
though) so for user the <id> would be the unique identifier.  If I try to use 
simple pattern matching I will run into an error as I can't write twice to the 
same URI.   

I came across this post explaining how to solve this issue 
http://www.stylusstudio.com/xsllist/200705/post10050.html  but it is still not 
clear to me what would be the best way to approach this.

Should I write e.g. functions for all possible types to extract the distinct 
URIs and do a second iteration that drops the URI from the sequence and if it's 
not present anymore skip processing the object twice?

<xsl:function name="pelssers:getURI">
  <xsl:param name="crontask" as="element(crontask)"/>
  ...TODO...
</xsl:function>

<xsl:function name="pelssers:getURI">
  <xsl:param name="user" as="element(user)"/>
  ...TODO...
</xsl:function>



"Here's a solution that I normally use. Take all URIs that you want to write 
to, pack them in a sequence and deduplicate them (use the function 
distinct-values or similar) and go from there (if possible) or, if you can't, 
you can use a micro-pipeline. I.e., the first transforms and changes the input 
and adds _1, _2 etc to the names, to ensure uniqueness, the second is the 
transformation where you create the actual result document."

<?xml version="1.0" encoding="UTF-8"?>
<objects>
  <crontask>
    <name>SyncDB</name> <!-- name is identifier -->
    <definition>Syncs filesystem with database</definition>  
  </crontask>
  <user>
    <id>12345</id>  <!-- id is identifier -->
    <name>Robby Pelssers</name>    
  </user>
  <!--   duplicate entry for same user needs to be skipped although name is 
different  -->   
  <user>
    <id>12345</id>  
    <name>Robby PelssersXX</name>       
  </user>    
</objects>

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