Often, elements should have a default attribute value if none is specified in the XTP file. An <example> tag might have a default CSS class of "example", but let the XTP change the default. In a template, xsl:if will conditionally produce XML depending on an XPath expression. The following example adds the class attribute to the table depending on the class value in the <box> element. If the XTP file specifies the class, the stylesheet will use it. The the XTP file doesn't specify the class, the stylesheet will use "example" as a default. <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:template match="example"> <table> <xsl:attribute name="class"> <xsl:if test="@class"> <xsl:value-of select="@class"/> </xsl:if> <xsl:if test="not(@class)">example</xsl:if> </xsl:attribute> <tr> <td> <xsl:apply-templates/> </td> </tr> </table> </xsl:template> </xsl:stylesheet> The example XTP does not specify class, so the stylesheet will use "example" as the default class. <example> This is an example. </example> <table class="example"> <tr> <td>This is an example</td> </tr> </table> StyleScript's $if uses the test expression for its first argument. If the expression is true, the block is used as a value. If false, the block after the $else will be used for the value. $template(example) << <table> $attribute("class") << $if(@class) <<@class>> $else <<example>> >> <tr> <td> $apply-templates(); </td> </tr> </table> >> evaluates conditionally. negates a boolean.
