Hi,

i have the following : Blocks contain properties and can be nested. There is a tag called BlockParameterDefaults that contain default properties for each Block

<BlockParameterDefaults>
  <Block>
    <property name="BlockType" value="Gain" />
    <property name="gain" value="1.00" />
  </Block>

  <Block>
    <property name="BlockType" value="Sum" />
    <property name="Inputs" value="2" />
  </Block>
   ...
</BlockParameterDefaults>

and then :

  <Block>
    <property name="BlockType" value="Gain" />
    <property name="Name" value="my_Gain" />
  </Block>

what i want to do is to lookup for some property inside a Block, and when it is not found, get its value from BlockParameterDefaults. I know how to do that and i wrote a function :

<!-- lookup for a property and returns its value. If the property is not found in the current block, try to look for it in the <BlockParameterDefaults> under /Model
    -->
    Ã‚ Â
  <xsl:function name="mdl2sig:lookup_property">
    <xsl:param name="block_node" />
    <xsl:param name="property_name" />

    <xsl:choose>
    Ã‚  <xsl:when test="$block_node[property[@name=$property_name]]">
        <xsl:value-of select="$block_node/property[@name=$property_name]/@value" />
    Ã‚  </xsl:when>
    Ã‚  <xsl:otherwise>
        <xsl:value-of select="/*[position()=1]/BlockParameterDefaults/Block[property[@name='BlockType' and @value=$block_node/property[@name='BlockType']]/@value]/property[@name=$property_name]/@value" />
    Ã‚  </xsl:otherwise>
    </xsl:choose>
  </xsl:function>

but the processor tells : XPDY0002: Cannot select a node here: the context item is undefined

(it refers to the otherwise clause).

It seems logical because functions don't have contexts, but here i'm selecting a node with an absolute path, it should work, shoulnd't it ?

<BlockParameterDefaults> is always located under /Model or /Library
'/' = root

Thanks

The term "absolute path" is misleading and is not used in XPath 2.0, because it's not absolute at all, it's relative to the root node of the current document. The function needs to be given a parameter that tells it which document to look within, and the path needs to start $doc/...

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

Ok thank you again. I'll try to pass the appropriate parameter.