Re: Optional attributes

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From: Shane Sendall (
Date: Tue 18 May 2004 - 20:56:08 BST

I don't really know. It is probably possible to send it directly to the 
submission team or formally through the OMG list. I would certainly try 
to send it to the submission team first. I have cc-ed Jos. He will at 
least know the right person to talk to if that isn't him even. I think 
there still should be time for changes before finalization, but I'm not 
sure of the schedule. I guess they will just need to agree with our 
analysis of the situation and eventually the proposal.
I would nevertheless be still for an additional 'oclIsNull' operation 
(especially as it is basically syntactic sugar and hence doesn't require 
much effort to add). As you say 'isEmpty' is inelegant and even 
misleading IMO

Jos, I have also some other suggestions. Can you keep me in the loop 
(wrt your response)?


John Daniels wrote:

>Hi Shane,
>>With this approach, "null" values can still be represented for entities
>>with a [0..1] multiplicity constraint. In this case, we could have an 
>>operation "oclIsNull", which returns true if the result is empty, and 
>>false otherwise, making use of OCL's double interpretation 
>>(object/collection) of navigation to entities with [0..1].
>We already have isEmpty() and notEmpty() which, while inelegant, do
>the job. They are what I've always used.
>Do I need to submit something formally to someone to get this whole
>issue looked at during the finalization?

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