- From: <noah_mendelsohn@us.ibm.com>
- Date: Wed, 16 Aug 2006 14:24:01 -0400
- To: "Michael Kay" <mike@saxonica.com>
- Cc: "'Antoli, Leo'" <Leo.Antoli@Misys.com>, xml-dev@lists.xml.org, xmlschema-dev@w3.org
XML Schema made a design decision to go with single rather than multiple inheritance in the type system. First of all, there are quite a few complexities that come of doing multiple inheritance in any language. Look careuflly at what C++ does to achieve this, for example, and you'll realize that it's tricky. In the particular case of XML, there is the issue that the order of elements is significant. If you inherit from complex combinations of base types, it can be rather tricky to figure out what a sensible order for the actual content would be, and whether users would even like it. Sunstitution groups in XML Schema depend on the type system, so the constraint to single inheritance is "inherited" there. Noah -------------------------------------- Noah Mendelsohn IBM Corporation One Rogers Street Cambridge, MA 02142 1-617-693-4036 --------------------------------------
Received on Wednesday, 16 August 2006 18:24:16 UTC