xsl:with-param
xsl:apply-templates
xsl:call-template
xsl:variable
ELEMENT: xsl:param
<xsl:param
name="qname"
>
</xsl:param>
Or:
<xsl:param
name="qname"
select="expression"
/>
The
xsl:param
element is used to declare a local or global parameter and to give that parameter a name and a default value. The default value will be used only if no other value is provided when the template is called.
The default value can be assigned by either the content of the
xsl:param
element or by the
select
attribute, but not by both. Each parameter declaration requires a separate
xsl:param
element. Global parameters are declared in the top level of the style sheet (as children of the
xsl:stylesheet
or
xsl:transform
elements). Local parameters are declared by using the
xsl:param
element as a child of the
xsl:template
element.
The actual (explicit) value is set by using
xsl:with-param
element when the template is applied (invoked) by either the
xsl:apply-template
or the
xsl:call-template
elements.
The
xsl:variable
element can also be used to declare local and global variables. The only real difference between a variable and a parameter is how the value is assigned.
Like all XSLT elements, the
xsl:param
element must be closed (well-formed). If the
select
attribute is present, then this element is self-closing. If the
select
attribute is not present, then this element is not self-closing and the separate closing element is mandatory.
name="qname"
The mandatory
name
attribute is the qname of the expression. A qname is a qualified name that is composed of an optional namespace prefix, a colon which is only present if there is a prefix, and a mandatory XML name (for example, xsl:zipcode or zipcode). Note the following rules concerning when two different parameters can have the same name. (The same rules apply to the
name
attribute of the
xsl:variable
element.)
A name can be repeated if one of the names is in an imported stylesheet and therefore has a lower import precedence. Under these circumstances, the higher import precedence name will always have precedence.
Two different parameters can have the same name if they can never occur within the same scope. Therefore no ambiguity can occur (which would be an error).
A local and global parameter can have the same name. However, when the local parameter is in scope, the global parameter cannot be accessed.
If the
name
attribute is assigned, a
select
attribute is not assigned, and there is no content, then the named parameter is set to be the empty string.
select="expression"
The optional
select
attribute is an expression that defines the parameter. If the
select
attribute is present, then the
xsl:param
element cannot contain any content and is self-closing. If an expression is given, the data type must be Boolean, node-set, number or string. If it is a (literal) string, the string must be enclosed within opening and closing quotes and in turn, that default value must be enclosed again in opening and closing quotes. For example:
<xsl:param name="car" select=" ' Ford ' " />
Or
<xsl:param name="car" select=' " Ford " ' />
If the
name
attribute is assigned, a
select
attribute is not assigned, and there is no content, then the named parameter is set to be the empty string for the default value.
We use the
DevGuru Staff List XML file
for our example with the following header:
<?xml-stylesheet type="text/xsl" href="xslt_example_param.xsl"?>
and we name it: xslt_example_param.xml
Code for xslt_example_param.xsl:
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:variable name="hoo">
<html>
<body>
<xsl:call-template name="boo">
<xsl:with-param name="name" />
<xsl:with-param name="dob" />
</xsl:call-template>
</body>
</html>
</xsl:variable>
<xsl:template name="boo" match="/">
<
xsl:param name="name"
/>
<
xsl:param name="dob"
/>
<xsl:for-each select="devguru_staff/programmer">
<div>
NAME: <xsl:value-of select="name" />
<br />
DOB: <xsl:value-of select="dob" />
<hr />
</div>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
Output:
Click to view output in separate window
- requires Internet Explorer
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