Subject: Re: Can solve the N-queens - but can't count! From: James Clark <jjc@xxxxxxxxxx> Date: Thu, 17 Jun 1999 17:03:08 +0700 |
Oren Ben-Kiki wrote: > Is this legal today? James clark wrote: > > >You cannot use a variable as a location step, but the above examples are > >valid. See production [18] PathExpr. > > And yes, PathExpr does allow "$Variable" as the first thing in a path > (section 6.2.1, "PrimaryExpr") However, giving XT the above or even: > > <xsl:copy-of select="$var/a"/> > > Causes the error: > > DID NOT EXPECT cannot convert to node-set $var has to be a node-set. The WD says this in 4th paragraph of section 6.2.2. > And there's no word in the limitation sections about this. Given James is > also the editor of the draft and the implementer of XT, I find the whole > combination somewhat confusing. Examining the draft, I find that the > introduction to section 6 states: This is not relevant. "Patterns" are the things that occur in match attributes in xsl:template. > "The only operations that can be performed on a result tree fragment are to > convert it to a string or a boolean. In particular, it is not permitted to > use the /, //, and [] on result tree fragments. > > Expressions can only return values of type result tree fragment by > referencing variables of type result tree fragment or calling extension > functions that return a result tree fragment." > > However it isn't defined what a "result fragment" is (there's an editorial > note to fix that). I _assumed_ that a variable holding a node set would > qualify, in which case the code above is invalid and XT is correct. The value of a variable is a result tree fragment if you define the variable it using xsl:variable without an "expr" attribute. For example, if you do: <xsl:variable name="x"><xsl:apply-templates/></xsl:variable> the $x refers to a result tree fragment, so doing <xsl:copy-of select="$x/a"/> is an error. On the other hand if you do: <xsl:variable name="x" expr="//foo"/> then $x refers to a node-set, so you can legally do <xsl:copy-of select="$x/a"/> See the third paragraph of Section 13. James XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
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