XSLT identity transform with append and root element namespaces - xslt

Question

I'm trying to create an XSLT library for the common task of passing through most of the content of XML data with small alterations.
The include file currently looks like this (pass-through.xslt):
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<!-- change default behaviour to copying all attributes and nodes -->
<xsl:template match="#*|node()">
<xsl:copy>
<xsl:apply-templates select="#*|node()"/>
</xsl:copy>
</xsl:template>
<!-- copy element but add a child node -->
<xsl:template name="append">
<xsl:param name="element"/>
<xsl:param name="appendage"/>
<xsl:element name="{name($element)}">
<xsl:copy-of select="$element/namespace::*"/>
<xsl:copy-of select="$element/#*"/>
<xsl:apply-templates select="$element/node()"/>
<xsl:copy-of select="$appendage"/>
</xsl:element>
</xsl:template>
</xsl:stylesheet>
You could then create a stylesheet which included it and not have to worry repeating yourself over and over (calling stylesheet).
<xsl:stylesheet version="1.0"
xmlns:ns="http://example/namespace"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:include href="pass-through.xslt"/>
<!-- only worry about the transform you want -->
<xsl:template match="element-to-be-modified">
...
</xsl:template>
</xsl:stylesheet>
If you only want to add an element to the document then call "append".
<xsl:stylesheet
This works except for namespaces on an element I'm appending to. If I have an XML file with a namespace on the root element it chokes saying there is no namespace binding for the prefix. If I add the namespace of the root element to the library then it's happy but that kind of defeats the purpose of the library if you've got to go modifying it for every use.
I'd be happy adding the xmlns:ns="uri" to the calling stylesheet but the scope of the namespace declaration seems to only extend to that stylesheet - not to the included one where the "append" template is.
I'd like to be able to transform
<ns:root xmlns:ns="http://example/namespace">
<ns:child>old child</ns:child>
</ns:root>
To
<ns:root xmlns:ns="http://example/namespace">
<ns:child>old child</ns:child>
<ns:child>new child!</ns:child>
</ns:root>
Without having to include the identity transform boilerplate every time. I've tried an assortment of things, including adding a namespace="{namespace-uri()}" to the element in the "append" template but nothing seems to preserve the namespace prefix on the element appended to.

Answer 1

Replace
<xsl:element name="{name($element)}">
by
<xsl:element name="{name($element)}" namespace="{namespace-uri($element)}">

Answer 2

If, when you call your named template "append" you are already positioned on the element you are copying/modifying, then there really is no need to pass the current element as a parameter. You can just use xsl:copy here
<xsl:template name="append">
<xsl:param name="appendage"/>
<xsl:copy>
<xsl:apply-templates select="#*|node()"/>
<xsl:copy-of select="$appendage"/>
</xsl:copy>
</xsl:template>
In your example, you would just call it like this
<xsl:template match="ns:root">
<xsl:call-template name="append">
<xsl:with-param name="appendage"><ns:child>new child!</ns:child></xsl:with-param>
</xsl:call-template>
</xsl:template>
Using xsl:copy should copy your element and retain the namespace.