Subject: Re: [xsl] how to estimate speed of a transformation From: David Carlisle <davidc@xxxxxxxxx> Date: Thu, 11 Dec 2003 09:42:14 GMT |
<xsl:template name="footer"> <xsl:variable name="doctitle" select="/book/descendant::title[1]"/> the programmer should expect that the computation takes place only once. Moreover, if it takes the form I seem to remember discussion on this list before now whereby some systems will evaluate that no times (if the variable isn't used) or just once, or each time it is referenced, depending on heurstics trying to trade off cost of computation against cost of storing teh result. One of the advantages of a side effect free langage is that you have the choice of recalculating rather than storing. one should have the right to expect that for each n the computation is performed once, and if a template is called with the same value of 'n' repeatedly, it does not spend time on computing doctitle again. The system doesn't have to re-calculate; it could cache the values so if it sees the same n again, simply re-use it. David -- http://www.dcarlisle.demon.co.uk/matthew ________________________________________________________________________ This e-mail has been scanned for all viruses by Star Internet. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk ________________________________________________________________________ XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
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