Re: [xsl] boolean(string(false())) is true - always?

["Martin Honnen martin.honnen@xxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

On 02.03.2017 16:00, Michael MC<ller-Hillebrand mmh@xxxxxxxxx wrote:

> <xsl:function name="dy:isFoo" as="xs:boolean">
>     <xsl:param name="node" as="node()"/>
>     <xsl:choose>
>       <xsl:when test="$node[self::bar/@foo = 'x']">
>             <xsl:value-of select="true()"/>
>         </xsl:when>
>         <xsl:otherwise>
>             <xsl:value-of select="false()"/>
>         </xsl:otherwise>
>     </xsl:choose>
> </xsl:function>
>
> and changed that to the more elegant:
>
> <xsl:function name="dy:isFoo" as="xs:boolean">
>     <xsl:param name="node" as="node()"/>
>     <xsl:sequence select="exists($node[self::bar/@foo = 'x'])"/>
> </xsl:function>
>
> BUT then I looked at my old code and said to myself: This could never have worked?!
>
> Isn't xsl:value-of creating a text node, so in xsl:otherwise it creates 'false'. And if this is cast to boolean as the function requires, we should get true(), because the string is not empty?

I think the rules lay out that the text node with 'true' or 'false' is 
atomized to xs:untypedAtomic 'true' or 'false' and then the conversion 
to xs:boolean is defined as a cast based on the XSD schema spec which 
treats 'true' as the boolean value true and false as the boolean value 
false. So what happens in language terms would be
   'true' cast as xs:boolean
which gives the boolean value true respectively
   'false' cast as xs:boolean
which gives the boolean value false and not
   boolean('false')
which would give the boolean value true.