Code review comment for lp:~zorba-coders/zorba/structuralrelationships2

> Federico, I think the documentation in node-position.xq needs some more work.
> I can do this, but first we must agree on what is exactly the functionality
> and the assumptions about node positions that you rely on. For example, in the
> documentation of the np:node-position() function, you write:
>
> "The returned URI is stable, i.e. it does not change when other nodes are
> inserted, deleted or modified"
>
> Do you rely on this? If not, then we shouldn't write it down.

Yes, at the moment I am relying on it. It could be possible however, with some
limitations, to lift off this requirements. I have not a clear idea at the moment
of the limitations involved or the amount of work required to do so. If you think
is bad to promise that uri are stable I can look into it.

>
> Also, look at the following rewrite of the ancestor-of function. Do you agree
> with it?
>
> (:~
> : Determines whether the node position that is given as second argument is
> : an ancestor of the node position is given as first argument.
> :
> : If the two positions were obtained within the same snapshot S, then the
> : result of the function applies to the corresponding nodes as well, that
> : is, within snapshot S, the second node is an ancestor of the first.
> : Otherwise, the result of the function does not imply anything about the
> : positional relationship of the two nodes.
> :
> : @param $pos1 the potential descendant node position
> : @param $pos2 the potential ancestor node position
> :
> : @return true if the node position $pos2 is an ancestor of the node position
> : $pos1; false otherwise.
> :
> : @error zerr:ZAPI0028 if one of the given URI is not a valid node
> : position computed by the <tt>np:node-position</tt> function.
> :)
> declare function np:ancestor-of(
> $pos1 as xs:anyURI,
> $pos2 as xs:anyURI) as xs:boolean external;

Yes, I agree with it. When I wrote this I was a little scared to say that a
structural relationship was ancestor of another, but now that they are called
node positions it should be ok. I am doing it.

Federico