Part11e2: Interfacing (USE/REF) meets SUBTYPE_CONSTRAINT

[Jochen Haenisch]

Thanks, Ed :-) I have no problem to agree to treat subtype-constraints like
global rules, i.e. to not allow explicit interfacing.
Best regards, Jochen.
____________________________________________________________
Jochen Haenisch			E-mail: Jochen.Haenisch at epmtech.jotne.com
EPM Technology AS		Home of the EXPRESS Data Manager
P.O Box 6629 Etterstad		Tel: Int + 47 23 17 17 26; mobile: Int + 47
922 60 274
N-0607 Oslo				Fax: Int + 47 23 17 17 01  
Norway					Web:  http://www.epmtech.jotne.com

> -----Original Message-----
> From:	Ed Barkmeyer [SMTP:edbark at nist.gov]
> Sent:	21. mai 2002 16:31
> To:	Jochen Haenisch
> Cc:	Phil.Spiby at eurostep.com; SC4 WG11
> Subject:	Re: Part11e2: Interfacing (USE/REF) meets SUBTYPE_CONSTRAINT
> 
> Jochen,
> 
> > did you in your discussions on interfacing subtype_constraints agree 
> > whether they can be USEd, REFERENCEd, or both?
> 
> Per clause 11, you can only USE named types (the concept
> "instantiation" only applies to types).
> 
> The current clause 11 does not allow RULEs to be explicitly interfaced
> via REFERENCE, so I don't see why it should allow SUBTYPE_CONSTRAINTs
> to be interfaced; they are a kind of global rule.
> 
> In my mind, the only Clause 11 issues are: 
> - Under what circumstances is a SUBTYPE_CONSTRAINT implicitly interfaced?
> 
> - If a SUBTYPE_CONSTRAINT is interfaced but not all of the entity types 
> involved in it are interfaced, what constraint is actually interfaced?
> 
> Note that for a RULE, the constraint would only be interfaced if
> *all* of the entity types involved in it are interfaced.  But,
> because a subtype-expression can include several *separable* constraints,
> we have Annex C.  And because SUBTYPE_CONSTRAINT doesn't fix this, we
> extend Annex C.
> 
> -Ed
> 
> -- 
> Edward J. Barkmeyer                       Email: edbark at nist.gov
> National Institute of Standards & Technology
> Manufacturing Systems Integration Division
> 100 Bureau Drive, Mail Stop 8260          Tel: +1 301-975-3528
> Gaithersburg, MD 20899-8260               FAX: +1 301-975-4482
> 
> "The opinions expressed above do not reflect consensus of NIST,
> and have not been reviewed by any Government authority."