RE: number collapsing

> >>        <xsl:when test="$begin castable as xs:integer">
> >>          <xsl:variable name="begin2" select="$begin" 
> as="xs:integer"/>
> >
> > This may fail if $begin is a string. The string "123" is castable to
> > xs:integer, but not assignable to xs:integer.
> 
> I'm not following here.  Aren't I saying in the function "if 
> $begin is 
> an integer, then apply this logic to determine how to shorten 
> $end; if 
> not, then just print $end as is"?

No, you are saying "if $begin is capable of being cast to an integer, then
assign it to an integer, and then...". But the fact that $beging is capable
of being cast to an integer does not mean it is capable of being assigned to
an integer; having established that the cast is possible you must then do
the cast. The logic for "castable" is always


if (A castable as B)
  then f(A cast as B)
  else ...

Specifically, if $begin is a string in the form "123" then the "castable as"
test will succeed, but the assignment will fail. Assignment does not do an
implicit cast. (However, if $begin is untypedAtomic, then your logic works
correctly, because untypedAtomic is a "weak" type that is automatically
converted to the required type when necessary). 

Michael Kay
http://www.saxonica.com/