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:template name="hoo" match="/">
<html>
<body>
<xsl:for-each select="devguru_staff/programmer">
<xsl:call-template
name="boo">
<xsl:with-param name="myname"
select="name" />
<xsl:with-param name="mydob"
select="dob" />
</xsl:call-template>
</xsl:for-each>
</body>
</html>
</xsl:template>
<xsl:template name="boo">
<xsl:param name="myname"
select="'Not Available'" />
<xsl:param name="mydob"
select="'Not Available'" />
<div>
NAME: <xsl:value-of select="$myname" />
<br />
DOB: <xsl:value-of select="$mydob" />
<hr />
</div>
</xsl:template>
</xsl:stylesheet>
Output:
Click
to view output in separate window - requires Internet
Explorer
|
