Re: circular relationships ok?
From: Alexandr Savinov <spam_at_conceptoriented.com>
Date: Thu, 02 Mar 2006 18:40:13 +0100
Message-ID: <44072dfe$1_at_news.fhg.de>
>
> Ok, here goes:
>
> Net<-------\
> | |
> V |
> Constraint*|
> | |
> V |
> Token* |
> / \ |
> | -----/
> V
> Constant
>
> (* denotes "zero or more")
> ("Token" refers to either a constant or a Net, not both.)
>
> How would you do it?
> Maybe I'm blind but I simply don't see it.
> My problem is that the relations are directed. A Nrt doesn't
> refer to constraints and tokens, a net refers to constraints
> and the token optionally refers to another net.
> Even if I add a Token/Net table, I still have the circle.
Date: Thu, 02 Mar 2006 18:40:13 +0100
Message-ID: <44072dfe$1_at_news.fhg.de>
Volker Hetzer schrieb:
> Alexandr Savinov schrieb:
>> A model with cycles is not a concept-oriented model (theoretically). >> It is a strong constraint but it is part of the definition. Then the >> question is if it is useful or not. For any model there are examples >> which are non-trivial and very difficult to implement. Loops and >> cycles can be always avoided by introducing a common subconcept. If A >> and B mutual reference each other then we introduce a common >> subconcept C: >> >> A B >> \ / >> C
>
> Ok, here goes:
>
> Net<-------\
> | |
> V |
> Constraint*|
> | |
> V |
> Token* |
> / \ |
> | -----/
> V
> Constant
>
> (* denotes "zero or more")
> ("Token" refers to either a constant or a Net, not both.)
>
> How would you do it?
> Maybe I'm blind but I simply don't see it.
> My problem is that the relations are directed. A Nrt doesn't
> refer to constraints and tokens, a net refers to constraints
> and the token optionally refers to another net.
> Even if I add a Token/Net table, I still have the circle.
Try the following approach in order to find directions for arrows and establish an order without cycles. Assume that you do not have any entities and your model is empty. Then take, say, Net, and ask a question:
- Does net know what is a Constant? Can it exist without Constants? Is it created before Constants? Is it more general thing than Constant?
I thing yes, but you should decide yourself. If so then Net is positioned above Constant and any constant object can reference one object.
-- http://conceptoriented.comReceived on Thu Mar 02 2006 - 18:40:13 CET