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RE: Problem about imported schema type when processing XQuery
- From: "Michael Kay" <mike@s...>
- To: "'he harrison'" <harrison076@g...>
- Date: Thu, 3 Jan 2008 10:35:53 -0000
Sorry, I don't see how you can read the spec that way. ISSD
is defined "as the
in-scope schema definitions of a module", and "in-scope schema
definitions" is clearly defined in 2.1.1 as part of the static context.
This rule is clearly a static rule.
You say "I think participating ISSD is not a static concept, but a dynamic
one", but you don't really explain why you think
this.
Or perhaps I'm misunderstanding you, and you're not talking
about what the spec says, but about what you think it should say? That's a
different discussion, of course.
Regards,
Michael Kay
http://www.saxonica.com/
That still seems obscure....how about my understanding:
My
understanding is, for the most part, agree with yours explaination, the
difference is about "participating ISSD", I think participating
ISSD is not a static concept, but a dynamic one, it should not include all schema definitions
in imported module, but only those schema definitions that passed to
importing module along with variables or function return values. Those
schema definitions in imported modules which are not used by importing
modules do not belong to participating ISSD. Besides,
participating ISSD also include currently active XML document
imported schema definitions, and module itself imported schema
definitions. As to my previous example, module a.xq's imported
schema schema_a.xsd is module c.xq's participating ISSD(because the
type are passed by sub typing), schema_c.xsd also belongs to c.xq's
participating ISSD, while they both contain same definition for
"myType", therefore an dynamic error should be raised. But if we change
a.xq to:
module namespace ma="http://www.w3.org/TestModules/moduleA"; import
schema namespace simple="http://www.w3.org/XQueryTest/simple"
at "schema_a.xsd"; declare function ma:funcA() { ("40"
cast as simple:myType) cast as xs:int };
then no error should be
raised even a.xq and c.xq still have different ISSD that contain different
definition for "myType", because "myType" imported in a.xq will not be
passed to module c.xq therefore will not cause confusion.
I think
this understanding is in consistant with both "2.2.5 Consistency
Constraints" and the two spec. statements I've mentioned.
Thanks Xin
2008/1/3, Michael Kay <mike@s...>:
Since it does not import in-scope
schema definitions from the imported modules, the importing module
should not see what schema definitions are there in the imported
modules.Since they could not see each other, then how could they decide
whether their ISSD is "equivalent"? and it seems also meaningless to
compare their ISSD because they will not disturb each other.
This may be why the spec doesn't require an implementation to check
that the two ISSDs are compatible, but merely says that the results are
unpredictable if they are
not.
and
If a module could see the
imported module's schema definition, then why spec. still force the
importing module explicitly import necessary schema definition, since
these types will surely be imported from other module's
ISSD?
XSLT took
the decision that all imported schema definitions would be available
in all modules. However, that makes it harder to do separate
compilation of modules. I think the rule in XQuery
that each module must import all the schema definitions that it
needs is there in the belief that this will make separate compilation of
modules easier.
Michael Kay
http://www.saxonica.com/
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