Subject: RE: [xsl] news From: Dylan Walsh <Dylan.Walsh@xxxxxxxxxx> Date: Tue, 20 Feb 2001 10:25:32 -0000 |
> From: Michael Kay [SMTP:mhkay@xxxxxxxxxxxx] > Sent: Monday, February 19, 2001 8:44 PM > To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx > Subject: RE: [xsl] news > >> >> Can anyone please tell me how to test whether a variable has been >> defined? >> > >> >There is no such test. ... >> >> What if the variable may, or may not, be defined as a global >> variable in a >> stylesheet which imports or includes the stylesheet you are writing? > >It's always known at compile time which variables are in scope, because >xsl:import and xsl:include can be resolved at compile time. Therefore, >there's no point in having a run-time test on the existence of a variable, >any more than there is in C or Java. > >Mike Kay My point was you are writing a transformation that will be included into other stylesheets, that are supposed to set the variable, but perhaps don't. Maybe those stylesheets are being written by other people. As Jeni said "But if you're writing the stylesheet that's being imported/included, then you don't know what it's (going to be) imported/included into. I think that's what Dylan's talking about." In Java, you cannot invoke a method or a constructor without providing the correct number of arguments. As Jeni described, you could declare it in your template with a special default value that indicates it hasn't been set by the importing/including transformation (I believe you would have use a param rather than a variable to achieve this affect). I'm not saying that a run-time test for variables/params is a major omission from XSLT, just pointing out that there is a hypothetical use case for such a feature. XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
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