Re: Selecting the first item from a tokenized string

   Michael Kay wrote:

   > you can get the Nth item in a sequence using SEQ[N].
   > In the rare cases where that's inconvenient because
   > it changes the evaluation context, you can use
   > subsequence(SEQ, N, 1).

     When can this happen?  Can you show an example?

     Regards,

   --drkm





Michael meant that to be a meta-expression with SEQ and N standing for
Xpath expressions, but if you take them as real examples with SEQ and N
being Xpath expressions selecting elements SEQ and N respectively then
you have an example where SEQ[N] and subsequence(SEQ, N, 1) are not
equivalent, as in the first  N selects children of the current node (and
may have a different value for each SEQ element) and in the second N selects
an N element child from the current node (which will then be a sibling
not a child of SEQ) and this value will be cast to an integer.

so 
<x>
  <N>1</N>
   <SEQ>1<N>6</N></SEQ>
   <SEQ>2</SEQ>
   <SEQ>3<N>3</N></SEQ>
</x>


SEQ[N] selects the first and third SEQ (as they have N children)
SEQ[number(N)] selects the third SEQ (as that is the only one with an N
   child equal to its position())
SEQ[N] selects the first SEQ child as N selects an element whose value
     can be cast to the integer 1.




David








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