RE: (ROSE) Dependency and Association

[Angay, Huseyin (Huseyin)** CTR **]

As soon as a class's code refers to another class, an association exists --
that is, even passing an instance of a class as a parameter implies an
association. It could not be any other way -- a link is an instance of an
association and passing instances around involves a links.

A dependency between classes is more of a hint. We know there is some vague
relationship between those, but they don't ever refer to each other. I have
yet to see a useful case of this.
Dependencies are much more relevant between packages and components where
they indicate communication.


Now, there is a school of usage that says that all static references (i.e.
the class has an attribute that refers to another class) are modelled by an
association and all temporary ones (i.e. passing instances in as parameters,
or instantiating them temporarily inside methods) are modelled as
dependencies.
CASE tools encourage this convention by generating attributes for all
associations and making it hard to model non-attribute associations.
If you want to do this, and everyone in your team agrees, then there isn't
all that much of a problem with it. It is however useful to know why you are
breaking the rules.


Regards,
Huseyin Angay
Karabash Ltd.
www.karabash.co.uk



> ----------
> From:         David Day[SMTP:[EMAIL PROTECTED]]
> Reply To:     David Day
> Sent:         30 July 2001 12:41
> To:   [EMAIL PROTECTED]; [EMAIL PROTECTED]
> Subject:      Re: (ROSE) Dependency and Association
> 
> 
> My understanding is that an association exists between
> 2 classes when one class references the other, such as
> via an instance variable.  The reference is part of
> the class definition.
> 
> A dependency between classes is used when no
> association exists, but the arguments of an operation
> in the 1st class includes the 2nd class as a
> parameter.  Clearly, a dependency is created since you
> can't call the operation without knowing the 2nd class
> definition, but the reference isn't an integral part
> of the class definition.
> 
> I'm curious to know if anyone has a clearer
> understanding.
> 
> --- [EMAIL PROTECTED] wrote:
> > 
> > 
> > Hi, I am a Rose User.
> > 
> > My problem is :
> > when I should use the dependency and
> > when I should use the association.
> > 
> > Please tell me about the difference between the
> > dependency and
> > association.
> > 
> > In the UML1.3 specfication, I wonder what the
> > differnce is.
> > 
> > Thanks.
> > 
> > 
> >
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