Inside Xslt
The <xsl: apply-imports > Element
If you import a stylesheet with a template for, say, the <PLANET> element, and then define your own <PLANET> element, the imported version is overridden. How do you access the overridden version? You can use the <xsl:apply- imports> element.
In XSLT 1.0, this element has no attributes, and takes no content. In the XSLT 1.1 working draft, the <xsl:apply-imports> element can handle parameters, so this element may contain zero or more <xsl: with-param > elements (see Chapter 9 for the details on parameters).
As an example, Ill modify the <xsl:import> example we just saw. In this case, Ill add another column to the HTML table this example produces, labeled DATA, and Ill do that by overriding the <PLANET> template in rules.xsl with a new <PLANET> template in planets.xsl. The new template simply adds a new column to the table and then uses the old <PLANET> template for the rest of the data. Ill access the old template with <xsl:apply-imports> :
Listing 2.12 Using <xsl:apply-imports>
<?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:import href="rules.xsl"/> <xsl:template match="/PLANETS"> <HTML> <HEAD> <TITLE> The Planets Table </TITLE> </HEAD> <BODY> <H1> The Planets Table </H1> <TABLE BORDER="2"> <TR> <TD>Date</TD> <TD>Name</TD> <TD>Mass</TD> <TD>Radius</TD> <TD>Day</TD> <xsl:apply-templates/> </TR> </TABLE> </BODY> </HTML> </xsl:template> <xsl:template match="PLANET"> <TR> <TD>4/1/2002</TD> <xsl:apply-imports/> </TR> </xsl:template> </xsl:stylesheet>
Heres what the new version of rules.xsl looks like:
Listing 2.13 NewVersion of rules.xsl
<?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:template match="PLANET"> <TD><xsl:value-of select="NAME"/></TD> <TD><xsl:value-of select="MASS"/></TD> <TD><xsl:value-of select="RADIUS"/></TD> <TD><xsl:value-of select="DAY"/></TD> </xsl:template> </xsl:stylesheet>
You can see the results in Figure 2.4. Ive used one template to build on another, which is the closest youll get in XSLT to object-oriented inheritance.
Figure 2.4. Using <xsl:apply-imports> .
In the XSLT 1.1 working draft, you can also use stylesheet parameters with <xsl:apply-imports> , which means you can use <xsl:with-param> elements as the content of <xsl:apply-imports> . Youll get all the details on parameters and <xsl:with-param> in Chapter 9.