Marrow,

Thanks simply assigning  variable worked (never tried that because of all 
the "no variable reassignment" griping)

My thinking on the predicate was that the order of execution would be

1. evaluate value of the (current) position()-1
2. assign that value to position()
3. retrive the node given the assigned position

I guess my thinking was that = doesn't evaluate the truth a statement such as

x = x + 1

But rather 

(newvalue of x <--- (x - 1))

Anyway good stuff to know thanks again.

"Marrow" wrote:

> Hi Jason,
> 
> > Not trying to accomplish any thing was just messing around and thought
> that
> > it might be a good way to check for the last record in a group during a
> loop.
> > Since I can't reassign variables and position() tells me where in a loop I
> am
> > and position() can also be used to specify a node to look up it seemed
> (maybe
> > foolishly) that this was an easy way to know if the current node and
> previous
> > node for a given value match.
> 
> The position() function when used **outside** a predicate will give you the
> position within the currently processed node-set (e.g. that selected by a
> @select on <xsl:apply-templates> or <xsl:for-each>).  When the position()
> function is used **within** a predicate then it ruturns the index of the
> node within the nodes selected by the XPath expression to the left of the
> predicate.
> 
> Your problem remains...
> 
> >   <xsl:when test="/foo/bar[position()=position()-1]/@attrib">
> 
> read the bit inside the [] predicate! ;)
> 
> How can "position()=position()-1" ever evaluate to true???  It can't... x
> can never equal (x - 1)... complete impossibility!  ;)
> 
> Maybe one of those position()'s is the position prior to the predicate?  In
> which case you would need to store one to a variable first, e.g something
> like...
> 
>  <xsl:for-each select="bar">
>    <xsl:variable name="curr-posn" select="position()"/>
>    <xsl:choose>
>    <xsl:when test="/foo/bar[position()=$curr-posn -1]/@attrib">
>       ...
> 
> or even just calc the index, e.g.
> 
>  <xsl:for-each select="bar">
>    <xsl:variable name="prev-posn" select="position() - 1"/>
>    <xsl:choose>
>    <xsl:when test="/foo/bar[$prev-posn]/@attrib">
>       ...
> 
> Cheers
> Marrow
> 
> "Jason Burr" <JasonBurr@d...> wrote in message
> news:C68421B0-71EE-4519-B453-EEB0735C5504@m......
> > Hey Marrow,
> >
> > Not trying to accomplish any thing was just messing around and thought
> that
> > it might be a good way to check for the last record in a group during a
> loop.
> > Since I can't reassign variables and position() tells me where in a loop I
> am
> > and position() can also be used to specify a node to look up it seemed
> (maybe
> > foolishly) that this was an easy way to know if the current node and
> previous
> > node for a given value match. I am aware of Muenchian (you may have helped
> me
> > out with that).
> >
> > Anyway the context of that example would have been in
> >
> > <foo>
> >   <bar attrib='test'>
> >   <bar attrib='test'>
> >   <bar attrib='test2'>
> > </foo>
> >
> > <xsl:for-each select="bar">
> >   <xsl:choose>
> >   <xsl:when test="/foo/bar[position()=position()-1]/@attrib">
> >    <xsl:value-of select="@attrib"/>
> >   </xsl:when>
> >   <xsl:otherwise>
> >     <xsl:value-of select="@attrib"/> end of group
> >   </xsl:otherwise>
> >   </xsl:choose>
> > </xsl:for-each>
> >
> > Result expected
> >
> > test
> > test end of group
> > test2
> >
> > Clearly I didn't mess with the keys or anything for grouping but this
> would
> > work if the xml was ordered or if using the Muenchian Technique. (that is
> if
> > it evaluated like it does when using value-of)
> >
> > As far as it evaluating to nothing thats not completely true becuase if I
> > hard code in the value of the position
> >
> > <xsl:value-of select="/foo/bar[position()=3]/@attrib"/>
> >
> > The the result would be
> >
> > test2
> >
> > and if I do
> >
> > <xsl:value-of select="position()-1"/>
> >
> > I would get
> >
> > 0
> > 1
> > 2
> >
> > So my general question was why would that not evaluate to the value of the
> > node (which does exist) and return the value requested. Further if there
> is
> > no way for this to work then is there another way to evaluate the same
> thing
> > (the previous node processed in a for-each)
> >
> > Thanks,
> >
> > Jason
> >
> >
> >
> > "Marrow" wrote:
> >
> > > Hi Jason,
> > >
> > > > But that this never returns a result
> > > >
> > > > <xsl:value-of select="/foo/bar[position()=position()-1]/@attrib"/>
> > >
> > > Of course it won't ever return anything...  the predicate [] expression
> can
> > > never evalaute to true.
> > >
> > > > What I want to do here is look at the last record in a loop to see if
> I am
> > > > at the end of a grouping (begininig of the next actually)
> > >
> > > Based on what you have described so far (but not seeing more of the XSLT
> and
> > > XML) I'd say it'is unlikely that your current method of doing grouping
> will
> > > work.  There are a couple of ways of doing grouping in XSLT 1.0 - the
> > > Muenchian Technique and preceding-sibling technique.  I'm sure if you
> post
> > > an example of what your are trying to do someone will be able to show
> you
> > > how to do these.
> > >
> > > Cheers
> > > Marrow
> > > http://www.marrowsoft.com - home of Xselerator (XSLT IDE and debugger)
> > > http://www.topxml.com/Xselerator
> > >
> > >
> > > "Jason Burr" <JasonBurr@d...> wrote in message
> > > news:3CEE074F-AD95-4124-ADD2-8DB46106D9BA@m......
> > > > Can someone explain why doing this writes a number one less than the
> > > current
> > > > position.
> > > >
> > > > <xsl:value-of select="position()-1"/>
> > > >
> > > > Doing this will display a specific positions value
> > > >
> > > > <xsl:value-of select="/foo/bar[position()=3]/@attrib"/>
> > > >
> > > > But that this never returns a result
> > > >
> > > > <xsl:value-of select="/foo/bar[position()=position()-1]/@attrib"/>
> > > >
> > > > What I want to do here is look at the last record in a loop to see if
> I am
> > > > at the end of a grouping (begininig of the next actually)
> > > >
> > >
> > >
> > >
> 
> 
>