- From: <bugzilla@jessica.w3.org>
- Date: Mon, 10 Jan 2011 12:38:32 +0000
- To: public-qt-comments@w3.org
http://www.w3.org/Bugs/Public/show_bug.cgi?id=11713 Summary: [XPath 3.0] Rules for union types Product: XPath / XQuery / XSLT Version: Working drafts Platform: PC OS/Version: Windows NT Status: NEW Severity: normal Priority: P2 Component: XPath 3.0 AssignedTo: jonathan.robie@redhat.com ReportedBy: mike@saxonica.com QAContact: public-qt-comments@w3.org We currently say in 2.5.4.2 If the expanded QName of an AtomicOrUnionType is not defined as an atomic type or a union type in the in-scope schema types, a static error is raised [err:XPST0051]. We should restrict this so that the only union types allowed are what I will call "plain union types". A plain union type is one whose base type is xs:anySimpleType (that is, it is defined directly as the union of a number of atomic types, as opposed to a union type that is derived by restriction from another union type). The reason for this rule is that no atomic value will ever be an instance of a non-plain union type; it is pointless to allow such types to be used, for example in a function signature as the type could never be satisfied. We can then change this Note: <old> Note: The current (second) edition of XML Schema 1.0 contains an error in respect of the substitutability of a union type by one of its members: it fails to recognize that this is unsafe if the union is derived by restriction from another union. This problem is fixed in the current working draft of XML Schema 1.1, and implementers are advised to adopt the solution given there. It is likely that this specification will be updated to refer normatively to XML Schema 1.1 when that specification reaches Recommendation status. </old> to read: <new> Note: The current (second) edition of XML Schema 1.0 contains an error in respect of the substitutability of a union type by one of its members: it fails to recognize that this is unsafe if the union is derived by restriction from another union. This problem is fixed in XSD 1.1, but the effect of the resolution is that an atomic value labeled with an atomic type cannot be treated as being substitutable for a union type without explicit validation. This specification therefore allows union types to be used as item types only if they are defined directly as the union of a number of atomic types. </new> -- Configure bugmail: http://www.w3.org/Bugs/Public/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the QA contact for the bug.
Received on Monday, 10 January 2011 12:38:34 UTC