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xsltparameters

difference between xsl:param and xsl:variable

I am considering using either <xsl:param> or <xsl:variable> when defining an <xsl:template name="myTemplate"> that will be called in another XSL file.

Legacy code seems to use xsl:variable when being used in <xsl:template match="legacyTemplate">.

So what's the difference between xsl:param and xsl:variable when using it in <xsl:template name="myTemplate">?

Solution

  • The difference is that the value of an xsl:param could be set outside the context in which it is declared. For example, see:

    <xsl:template ...>
   <xsl:param name="p" select="'x'" />
   <xsl:variable name="v" select="'y'" />
...

    then you know that $v will always give you the string 'y'. But for $p the string 'x' is only a default: you will see a different value if the template is invoked with either xsl:apply-templates or xsl:call-template which contains an instruction such as:
    <xsl:with-param name="p" select="'not x'" />

    <xsl:param> may also be used outside xsl:template, at the top level in the stylesheet. The value of such a parameter may be set when the XSLT processor is called. How this is done depends on the processor and whether you call it from the command line or by program.