Re: xsl:system-property() introduces dynamic typing into XPath data model? from James Clark on 2000-02-13 (xsl-editors@w3.org from January to March 2000)

From: James Clark <jjc@jclark.com>
Date: Sun, 13 Feb 2000 11:52:56 +0700
To: Michael Fuller <msf@io.mds.rmit.edu.au>
CC: xsl-editors@w3.org
Message-ID: <38A638A8.21FD6A72@jclark.com>

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

Received on Saturday, 12 February 2000 23:54:39 UTC