Re: [xsl] Keys Context Management

["andrew welch" <andrew.j.welch@xxxxxxxxx>]

On 3/16/06, Karl Stubsjoen <kstubs@xxxxxxxxx> wrote:
> I have a couple of keys which I have defined like this;
>
> <xsl:key name="key_athletes"
> match="/ROOT/MeetResults/Meet/AthleteResults/Athlete" use="USAGNum"/>
> <xsl:key name="athlete_driver"
> match="/ROOT/NewDataSet[@Name='wbx_scoreupload']/Table"
> use="usagnum"/>
>
>
> Notice that I match right away off of ROOT.  I do this because I am
> not confident that the context for which the key belongs will be
> preserved.  I've written similar keys before where I am basically
> going after the last node of the tree to which I am after.
>
> How does context work with keys?
> Does the context of each key shift as you walk your XML?

Yes - all the key does is index nodes in the tree so that you can
select them faster... the nodes are still the same nodes in the same
tree.

You shouldn't really have a key that will only ever match one node, as
the cost of building the key will outweigh the selection gains, you
should use a variable instead.

cheers
andrew