<p:variable
name = QName
select = XPathExpression>
((p:empty |
p:pipe |
p:document |
p:inline |
p:data)? &
p:namespaces*)
</p:variable>Variables can only be generated in Compound Steps. They include values which are defined via an appropriate XPath expression. The name of a variable has to be a QName. They can be further used within this step. They can also be loaded with <p:empty>, <p:pipe>, <p:document>, <p:inline> or <p:data> (afterwards, the "select" attribute extracts the desired contents and stores them in the variable).
Example
In the following example the use of <p:variable> is demonstrated.
<?xml version="1.0" encoding="UTF-8"?>
<p:declare-step xmlns:p="http://www.w3.org/ns/xproc" xmlns:c="http://www.w3.org/ns/xproc-step" version="1.0">
<p:input port="source">
<p:inline>
<block>
<fileName>test.xml</fileName>
<text>This is just a small example text.</text>
</block>
</p:inline>
</p:input>
<p:output port="result">
<p:empty/>
</p:output>
<p:group>
<p:variable name="Inline" select="block/fileName"/>
<p:identity/>
<p:store>
<p:with-option name="href" select="$Inline"/>
</p:store>
</p:group>
</p:declare-step>In the example a XML document is generated by <p:inline>. This document has a value in the “fileName“ element which shall be assigned to the variable. In order to be able to generate a variable, it has to be within a Compound Step. Therefore, <p:group>, a Compound Step, is used as enclosing element. The variable gets the name “Inline“ and “text.xml“ as value, this corresponds to the return value of the indicated XPath expression. The <p:identity> step re-outputs the entire content of <p:inline> which then becomes the content of <p:store> and is stored by it. As file name the value stored in the variable is used. The content of the variable is resolved by the preceding Dollar character ($) and so it can be used as file name.
The result of this pipeline is as follows: