RE: [xsl] Can I use a boolean variable in an xsl:if test

Subject: RE: [xsl] Can I use a boolean variable in an xsl:if test
From: Wendell Piez <wapiez@xxxxxxxxxxxxxxxx>
Date: Tue, 08 Feb 2005 14:29:48 -0500
At 10:58 AM 2/8/2005, Mike wrote:
<xsl:variable name="show">
  <xsl:value-of select = "$time != 60000" />

is not a boolean variable, it is a result tree fragment. If you convert a
result tree fragment to a boolean, the result is always true.

The correct way to write a boolean variable is:

<xsl:variable name="show" select="$time != 60000" />

I simply have no idea why this verbose, inefficient, and often incorrect
style using <xsl:value-of> within <xsl:variable> has become so popular.

My guess is that newbies imagine xsl:value-of to be some kind of "evaluate" function. Of course what it really is, is an instruction to write a string to a result tree (to "the" result tree or to a result-tree-fragment, as the case may be). Since this is generally what we want to have happen to our results, there seems to be nothing to get confused about.

Until it breaks, that is, because we're not writing it out, but doing something else with it instead. Like testing whether it's true, while imagining we're testing the expression that was evaluated for it.


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