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Re: [xsl] comparing attributes if missing at times

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see the comments about != in the recent thread on text() (if you followed it that far:-)

Applying != to sequences that you do not know have exactly 1 element is well defined but rarely useful.

Given

<x>
<elem x="1"/>
<elem x="1"/>
<elem x="2"/>
<elem/>
<elem x="3"/>
</x>

compare the results of

<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<xsl:template match="elem">
<elem

test1="{@x != preceding-sibling::elem[1]/@x}"
test2="{not(@x = preceding-sibling::elem[1]/@x)}"
test3="{string(@x) != preceding-sibling::elem[1]/string(@x)}"
test4="{not(string(@x) = preceding-sibling::elem[1]/string(@x))}"
>
<xsl:copy-of select="@*"/>
</elem>
</xsl:template>
</xsl:stylesheet>

you get:

<elem test1="false" test2="true" test3="false" test4="true" x="1"/>
<elem test1="false" test2="false" test3="false" test4="false" x="1"/>
<elem test1="true" test2="true" test3="true" test4="true" x="2"/>
<elem test1="false" test2="true" test3="true" test4="true"/>
<elem test1="false" test2="true" test3="true" test4="true" x="3"/>

Note that string() ensures that you get exactly one value (a possibly empty string) rather than @x which may return a sequence of length 0 or 1.

David

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