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W. E. Perry wrote:
>
> I'm sorry, Jonathan, I don't understand. What is
>
> return $stock/price / ($stock/revenues - $stock/expenses)
>
> except the execution of subtraction and division arithmetic
> operations agains t the 'values' of $stock/price,
> $stock/revenues, and $stock/expenses? And if your query
> is against XML, then the values of those i tems are
> runs of Unicode text, and your arithmetic operations
> are effectively meaningless.
Not necessarily: the infix operator "-" can easily be
defined as an operation on strings. Parse the left and
right operands as numbers (raising an error if they're not
syntactically valid), subtract one from the other, then
format the result as a string.
That's precisely how Tcl works. That's why I find Tcl
eminently suitable for processing SGML: "everything is a
string" is a mantra that works in both worlds. (And no,
contrary to popular belief, this doesn't make Tcl horribly
inefficient.)
I don't know if XQuery works that way -- haven't kept up
with the spec. XPath does, sort of, except that it has
IEEE floating point as a built-in data type in addition
to strings and that complicates things a bit.
--Joe English
jenglish@flightlab.com
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