XSLT, 2nd Edition

Variables

If we use logic to control the flow of our stylesheets, we’ll probably want to store temporary results along the way. In other words, we’ll need to use variables. XSLT provides the <xsl:variable> element, which allows you to store a value and associate it with a name.

The <xsl:variable> element can be used in three ways. The simplest form of the element creates a new variable whose value is an empty string (""). Here’s how it looks:

<xsl:variable name="x"/>

This element creates a new variable named x, whose value is an empty string. (Please hold your applause until the end of the section.)

You can also create a variable by adding a select attribute to the <xsl:variable> element:

<xsl:variable name="favouriteColour" select="'blue'"/>

In this case, we’ve set the value of the variable to be the string “blue”. Notice that we put single quotes around the value. These quotes ensure that the literal value blue is used as the value of the variable. If we had left out the single quotes, this would mean the value of the variable is the node-set (or sequence) of all the <blue> elements in the context node, which definitely isn’t what we want here.

Warning

Be aware that single quotes around numeric values are significant. The value 35 represents a numeric value (it’s a number in XSLT 1.0, and an xs:integer in XSLT 2.0), while the value '35' represents the string 35. That might seem like a minor distinction, but it has a major impact on how your stylesheet works, especially in XSLT 2.0.

The ...