Why XML data typing is hard

[Ketil Z Malde]

<david at megginson.com> writes:

> Liam R. E. Quin writes:
> 
>  > david at megginson.com wrote:

>  [...]

>  > >   Warning: sample.xml line 18 column 12: Cannot validate constraint
>  > >            "float" for unsupported language "ar" (trying default
>  > >            locale en-CA).

Hum, so what really was thousand (<value>1,000</value>), gets parsed
as one, since my default is a European locale.

>  > Maybe what you really need is
>  >     <balance xml:type="float" xml:lang='ar'> ...
>  > instead?

> That's almost exactly the markup that I was imagining would generate
> the warning, except that I'd use a different namespace for the lexical
> constraint attribute (no need to overload the magic "xml" namespace).

Perhaps somebody could explain to me the rationale of including the
xml:type attribute with the element, instead of in the element
*declaration* (in the DTD).  To me, this sounds as if another type would
make as much sense, say a date or integer, or what have you.

In my imagination, that would typcially get messy and cause the run
time errors we want to avoid, so I assume either there's an additional
restriction in the DTD, or there's some fundamental reason I overlook.

Enlightenment, please?

~kzm
-- 
If I haven't seen further, it is by standing in the footprints of giants

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