Design and coding patterns in XSLT

Question

I'm new to XSLT and have a general question. To distinguish two elements with different attributes, it is better (also for performance) to use <xsl:template match="foo[@aOne]"> and <xsl:template match="foo[@aTwo]"> instead of an <xsl:if test="@aOne"> within one single template. And as far as I understood, this is how one should "think" in XSLT. But in my oppinion, this has the disadvantage, that it leads to redundant parts of code.

For example: The matching of an element with two attributes

<foo aOne="asdf">
   ...
</foo>

<foo aTwo="asdf">
   ...
</foo>

The template would look like this:

<xsl:template match="foo[@aOne]">
    <div>
      <p> 
         <xsl:value-of select="@aOne"/>
      </p>
    </div>
</xsl:template>


<xsl:template match="foo[@aTwo]">
    <div>
      <p>
        <xsl:value-of select="@aTwo"/>
      </p>
    </div>
</xsl:template>

So one would have to write all the frame (like the <div> etc. in the example) several times.

Is there some kind of template design pattern like it is known from Java?

Or is it a totally wrong approach / view on programming XSLT?

Hope my idea got clear, thanks in advance for any comments.

Answer 1

Are the two attributes mutually exclusive? If so, I would write

<xsl:template match="foo[@aOne|@aTwo]">
    <div>
      <p> 
         <xsl:value-of select="@aOne|@aTwo"/>
      </p>
    </div>
</xsl:template>

If they are not mutually exclusive, then your approach of having two template rules seems inadequate: there would be four rules for the four possible combinations of @aOne being absent or present, and @aTwo being absent or present.

Answer 2

I don't want to draw any general rules. I think that in your specific example, you could do:

<xsl:template match="foo">
    <div>
        <p> 
            <xsl:apply-templates select="@*"/>
        </p>
    </div>
</xsl:template>

<xsl:template match="@aOne | @aTwo">
    <xsl:value-of select="."/>
</xsl:template>

or even:

<xsl:template match="foo">
    <div>
        <p> 
            <xsl:value-of select="@aOne | @aTwo"/>
        </p>
    </div>
</xsl:template>

or some other variation (we don't know enough about what the input may contain).