Re: Conditionally use attribute sets?

It can be done. Consider the following stylesheet (which you can test by 
applying it to itself):

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" 
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

  <xsl:output method="xml" version="2.0" omit-xml-declaration="no" 
indent="yes"/>

  <xsl:param name="who"/>

  <xsl:attribute-set name="Oscar">
    <xsl:attribute name="slob">yes</xsl:attribute>
  </xsl:attribute-set>

  <xsl:attribute-set name="Felix">
    <xsl:attribute name="slob">no</xsl:attribute>
  </xsl:attribute-set>

  <xsl:template match="/">
    <bachelor>
      <xsl:choose>
        <xsl:when test="$who='Oscar'">
          <xsl:attribute name="xsl:use-attribute-sets">
            <xsl:value-of select="'Oscar'"/>
          </xsl:attribute>
        </xsl:when>
        <xsl:when test="$who='Felix'">
          <xsl:attribute name="xsl:use-attribute-sets">
            <xsl:value-of select="'Felix'"/>
          </xsl:attribute>
        </xsl:when>
      </xsl:choose>
    </bachelor>
  </xsl:template>

</xsl:stylesheet>

I tested that with Xalan Java 2.4.1

It's easier in 2.0 because 

<xsl:attribute name="xsl:use-attribute-sets">
  <xsl:value-of select="'Oscar'"/>
</xsl:attribute>

can be

<xsl:attribute name="xsl:use-attribute-sets" select="'Oscar'"/>

I tested that with Saxon 8.5.1.

Jay Bryant
Bryant Communication Services
(presently consulting at Synergistic Solution Technologies)