On Fri, Apr 18, 2008 at 02:05:52PM +0100, Andrew Welch wrote:

Actually no. A conformant implementation is allowed to call an extension function only once for any given argument value, and to remember the results, to make it stable. A give implementation might let you write such an extension function as you want, but there's no guarantee.

In addition, suppose you have a stylesheet that does, say

xsl:for-each 1 to 1000 value-of current-time

the implementation doesn't have to start at 1 and evaluate the "loop" a thousand times. Instead, this could be written as, map the items in the sequence (1 ... 1000) to the value of current-time with current-time being called once.

Or, the implementation could start at 1000 and work downwards, and as long as it ended at 1 and put the results in the right order, you coudn't tell.

And yes, there are implementations that do that sort of thing :-) at least for XQuery and quite possibly for XSLT.

So, best to think of XSLT as specifying a mapping, rather than in terms of procedural instructions.

Hppe this helps, although it's perhaps notwhat you want to hear.

Best,