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

[Wendell Piez <wapiez@xxxxxxxxxxxxxxxx>]

At 10:58 AM 2/8/2005, Mike wrote:
> <xsl:variable name="show">
>   <xsl:value-of select = "$time != 60000" />
> </xsl:variable>
>
> is not a boolean variable, it is a result tree fragment. If you convert a
> result tree fragment to a boolean, the result is always true.
>
> The correct way to write a boolean variable is:
>
> <xsl:variable name="show" select="$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.

Cheers,
Wendell


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Wendell Piez                            mailto:wapiez@xxxxxxxxxxxxxxxx
Mulberry Technologies, Inc.                http://www.mulberrytech.com
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