Re: [xsl] Problem with "except" operator

[Martin Honnen <Martin.Honnen@xxxxxx>]

Andrew Welch wrote:
> > For the (short) example data posted it does not matter but in general I
> > think the above should be
> >  <xsl:value-of select="$users[not(. = $friends)]"/>
> > as that is quite different from $users[. != $friends].
>
> Is that right?  It always takes me a while to "get it" again, but I
> think you only need to be concerned about != when both sides are
> sequences of more than 1 item.  When the LHS is a single item, it's
> ok.
>
> So the above are equivalent.

I don't think so, if we have e.g.

<root>
  <Response>
    <Users>
      <Count>2</Count>
      <User>
        <Username>henry</Username>
        <Online>false</Online>
        <UserId>302</UserId>
      </User>
      <User>
        <Username>felix</Username>
        <Online>false </Online>
        <UserId>288</UserId>
      </User>
    </Users>
  </Response>
  <Response>
    <Friends>
      <Count>2</Count>
      <Friend>
        <UserId>288</UserId>
      </Friend>
      <Friend>
        <UserId>42</UserId>
      </Friend>
    </Friends>
  </Response>
</root>


then with
  $users[not(. = $friends)]
we select those User/UserId elements for which there is no Friend/UserId 
with the same value while
  $users[. != $friends]
selects those User/UserId elements for which there is at least one 
Friend/UserId element with a different value.



--

	Martin Honnen
	http://JavaScript.FAQTs.com/