Validating the output as it is generated makes it easier for
a stylesheet engine to identify precisely where
input/templates are misbehaving. This feature makes it much
closer to the 'error on line X' form of debugging most of us
are familiar with.
Agreed. I've got an early version of this working in Saxon, and I'm very
impressed with the potential for shortening the debugging loop.
That said, I do not think this needs to be a *language*
feature. Especially when it mandates one schema language to
the exclusion of all others. This kind of feature should be
left to implementors to figure out, not language designers to mandate.
I don't think that there's anything that excludes other schema
languages. The specs say how XSLT/XPath works with XML Schema; they make
that support optional; and if a vendor wants to do something to support
other schema languages, I don't think there's anything in the spec to
stop them.
And it is implementors who figured it out. It's just that they decided
to do it together, rather than separately.
Michael Kay
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