Subject: Re: [xsl] use-when attribute?|
From: Geert Josten <Geert.Josten@xxxxxxxxxxx>
Date: Mon, 20 Dec 2004 19:01:25 +0100
In short, it isn't hard for a system to evaluate this expression in a single scan, or perhaps three scans, and there is no need to allocate any memory for temporary results.
Even if the result of //a|//b|//c is assigned to a variable and you then do count() on the variable, the system may be able to tell that it doesn't need to allocate memory to hold the value (it might be able to see that it's only used once).
The main reason the key is slower in this case is that you are only using it once. But there's no good reason for ever using a key with a fixed use expression more than once, because you could always put the result of the first evaluation in a variable. So yes, I can't see any reason for using this construct.