[wg11] EXPRESS (DERIVEd) attribute redeclaration question

[Thomas Thurman]

On Jun 1, 2012, at 3:27 PM6/1/12, Lothar Klein wrote:

> It has been always this way.
> And the classical example is that if an entity A has an explicit
> INTEGER attribute and two subtypes B and C. In B the attribute is
> redeclared to be an odd number and in C to be an even number and there
> is an entity D that is a subtype of both, B and C then all this is
> valid Express. But it is not possible to construct a valid instance of
> D because you won't find an integer value that is both an odd and an even
> number simultaneously.
Sorry, we seem to be getting off track.
I was specifically talking about the case where there are three declarations in a direct supertype path,
The root supertype, an intermediate type and the leaf subtype.
Let's not mix up the problem statement.

Tom
> 
> Lothar
> 
> Friday, June 1, 2012, 3:42:25 PM, you wrote:
>> Phil,
>> This is an interesting conclusion. I look forward to hear opinions of other members of WG11.
> 
>> Tom
>>> On Jun 1, 2012, at 12:43 AM6/1/12, Phil Spiby wrote:
> 
>>> I believe Rule and Restriction (e) under section 9.2.3.4 applies:
>>> e) If an attribute of a supertype is redeclared in two non-mutually exclusive subtypes, an
>>> instance which contains both subtypes shall have a single value for that attribute which is
>>> valid for both redeclarations.
>>> 
>>> Phil
>