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At 10:45 AM 5/7/2002 -0400, Elliotte Rusty Harold wrote:
>At 3:26 PM +0200 5/7/02, Matthew Gertner wrote:
>> I can
>>certainly say from my experience programming in Java and C++ that I would
>>prefer for a number to be a number and for a date to be a date, rather than
>>having to constantly convert back and forth.
>You're assuming that everyone agrees with you on what a date is, and what
>a number is, and so forth. If you think about it, I suspect you'll realize
>that's not true. Is a number floating point or integer? What are its
>maximum and minimum values? Does a date type include dates after 10000 CE
>or before 1000 CE? Strings are reasonably portable. Dates and numbers
>aren't in practice. The local type I want to use may not be the type you
>want to send. XML lets us talk to each other in spite of that.
Yes, and a query language that uses the types in the XML view can operate
on a wide variety of data without worrying about the details of the
original data sources. Note that XML Schema supports these distinctions -
floating point, integer, maximum and minimum permitted values, the
representation of dates, etc. The fact that we have a portable way of
representing data types that answers these questions allows
system-independent processing of a wide variety of data.
>The schemas data types spec tries to address these problems by being all
>things to all people, but not all environments can handle integers that
>can exceed a googoolplex or dates that precede Julius Caesar. Your date
>type and my date type are not necessarily the same thing. Your number type
>and my number type are not necessarily the same thing.
But a more limited form of date or integer can be defined in XML Schema,
and used to represent integers in a system that can only handle, say, 16
bit or 8 bit integers.