Subject: RE: [xsl] Elements and functions available From: "Michael Kay" <mike@xxxxxxxxxxxx> Date: Wed, 22 Oct 2008 10:48:51 +0100 |
> Out of interest, can someone comment on the cost of calling > these functions? I imagine element-available() is very > cheap, but I'm wondering about function-available() with user > created extensions... Performance is always processor-dependent. If the argument to function-available is a literal, then Saxon is going to optimize away something like if (function-available('f:x')) then f:x() else () at compile time either to a call on f:x() or to (). On the other hand, with a run-time argument, function-available() in Saxon is probably very expensive. Much the same applies to element-available, since Saxon does allow user-written extension elements. Michael Kay http://www.saxonica.com/ > > Given a transform that makes use of many custom extensions, > is it reasonable to do: > > <xsl:choose> > <xsl:when test="function-available( )"> > normal execution > </ > <xsl:otherwise> > test execution > > ...to allow you to run the transform away from the host application? > Or would all the calls to function-available() adversely > affect normal running of the transform? > > The alternative (and good practice anway I think) is to move > all of the calls to extensions into one or maybe two physical > stylesheets, and then you can use an alternative primary > stylesheet that imports a different stylesheet where the > calls to the extensions have been replaced with sample values.... > > Either way, I'm just wondering if I should try to avoid lots of > function-available() calls? > > > > 2008/10/22 Jesper Tverskov <jesper@xxxxxxxxxxx>: > > I have tested the little used XSLT functions element-available() and > > function-available() and made a stylesheet that can create a report > > for most XSLT processors, testing also for EXSLT extensions > and Saxon > > extensions. > > > > I have made 8 reports available and a summary, "Elements > and functions > > available in XSLT processors", > > http://www.xmlplease.com/elements-functions. > > > > Feel free to suggest improvements. > > > > Best regards, > > Jesper Tverskov > > > > http://www.xmlplease.com > > > > > > > > -- > Andrew Welch > http://andrewjwelch.com > Kernow: http://kernowforsaxon.sf.net/
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