Re: how to change variable values ?

[Oliver Becker <obecker@xxxxxxxxxxxxxxxxxxxxxxx>]

Hi Gero,

> i got the following problem: i want to output a xml-document with a 
> xsl-stylesheet. In this output it should, for example, make a line when 
> the week changes. I tried to do this by using variables...
> 
> -------------
> <xsl:variable name="lastweek">
>   <!-- Need an Initial value to compare later with currentweek-->
>   <xsl:value-of select="Week"/>  
>   <!-- Week is a tag from the xml-document -->
> </xsl:variable>
> 
> <xsl:for-each select="Data/Block">
> 
>   <xsl:variable name="currentweek">
>     <xsl:value-of select="Week"/> 
>   </xsl:variable>
> 
>   <xsl:if test="$currentweek > $lastweek">
>     <!-- Do something when week changes and set
>          the variable lastweek to this week -->
>     <xsl:variable name="lastweek">   <!-- foo ;-) -->
>       <xsl:value-of select="$currentweek">
>     </xsl:variable>
>   </xsl:if>
>   
>   .
>   .
>   .
> </xsl:for-each>
> --------------------------
> 
> Obviously, it complains, that the variable lastweek cannot be defined 
> twice. Is there a way to "just change" the variable lastweek (and not 
> to define it again) ?

The only way to use variables with changing values is by recursion.
I.e. you define a named template and call it with passing your node-set
"Data/Block" and an initial lastweek value through parameters.
The template processes the first node and calls itself recursively
with all nodes but the first and a maybe updated lastweek parameter.

If you like, you may take a look at my "XSLT loop compiler" which allows
defining iterative loops and translating them into pure XSLT.
http://www.informatik.hu-berlin.de/~obecker/XSLT/#loop-compiler

However, I think your problem can be solved much simpler:
What about

  <xsl:if test="Week > preceding-sibling::Week">
    <!-- Do something when week changes -->
  </xsl:if>

Best regards,
Oliver


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