XSLT：如何优化基于多条件的变量赋值

Great question! Your current xsl:choose approach works, but we can make this cleaner and more maintainable depending on your XSLT version. Let's go through a few optimized options:

Option 1: Use XSLT 2.0+ Conditional Expressions (Simplest for Linear Conditions) #

If you're working with XSLT 2.0 or later, you can replace the nested xsl:choose with a concise inline conditional expression. This cuts down on boilerplate tag noise while keeping logic easy to follow:

<xsl:variable name="attribute-name" select="
  if ($var1 = 1) then 'attr1'
  else if ($var2 = 1) then 'attr2'
  else if ($var3 = 1) then 'attr3'
  else 'attr'
"/>

This reads like a plain English "if-else" chain and avoids the need for multiple <xsl:when> tags. Perfect for straightforward, linear condition checks like yours.

Option 2: Use a Map (Best for Scalable/Extensible Mappings) #

If you anticipate adding more variable-attribute pairs later, using a map (XSLT 3.0+) makes your code far easier to maintain. You define the mappings in one place, then fetch the correct value with minimal logic:

<!-- Define your variable-to-attribute mappings once -->
<xsl:variable name="attr-map" as="map(xs:string, xs:string)" select="
  map {
    'var1:1': 'attr1',
    'var2:1': 'attr2',
    'var3:1': 'attr3'
  }
"/>

<!-- Fetch the matching attribute name, fall back to 'attr' if none match -->
<xsl:variable name="attribute-name" select="
  ($attr-map[concat('var1:', $var1)],
   $attr-map[concat('var2:', $var2)],
   $attr-map[concat('var3:', $var3)],
   'attr')[1]
"/>

Now, if you need to add a new var4 that maps to attr4, you only update the attr-map—no need to touch the conditional logic. This is especially useful for larger sets of mappings.

Option 3: XSLT 1.0 Compatibility (Legacy Environments) #

If you're stuck on XSLT 1.0 (common in older systems), you can still clean things up by using a node-set to simulate mappings (requires an extension like EXSLT):

<xsl:stylesheet 
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
  version="1.0"
  xmlns:exsl="http://exslt.org/common"
  extension-element-prefixes="exsl"
>
  <!-- ... -->

  <xsl:variable name="attr-mappings">
    <mapping test="{$var1=1}" value="attr1"/>
    <mapping test="{$var2=1}" value="attr2"/>
    <mapping test="{$var3=1}" value="attr3"/>
  </xsl:variable>

  <xsl:variable name="attribute-name" select="
    (exsl:node-set($attr-mappings)/mapping[@test='true']/@value | 'attr')[1]
  "/>
</xsl:stylesheet>

This centralizes your mappings just like the XSLT 3.0 map, making future edits simpler than updating a long chain of <xsl:when> tags.

Final Note #

All these options work seamlessly with your existing attribute-setting code:

<tag>
  <xsl:attribute name="{$attribute-name}">Something</xsl:attribute>
  <!-- ... -->
</tag>

Pick the approach that fits your XSLT version and how likely you are to extend the mappings later!

内容的提问来源于stack exchange，提问作者aronadaal