Re: xsl:system-property() introduces dynamic typing into XPath data model?

Michael Fuller wrote:
> 
> The XSLT extenstion function "system-property()" (XSLT 12.4) is
> defined with a return type of "object":
> 
>     object system-property(string)
> 
> As far as I can tell, this is the only instance in XPath and XSLT
> where the return type cannot be explicitly known during parsing,
> but instead must be dynamically determined at run-time.

There are other cases, specifically references to variables declared by
xsl:param, and calls to extension functions.

> This makes implementing a type-safe XPath expression parser/evaluator
> _significantly_ more complicated.

Yes, I know.

James