Valid Values for an Attribute...

[AndyJ]

Hi people,

I must be missing the obvious here...

I have a class that contains a number of attributes.

Two of the attributes can only contain a very limited set of valid values. Lets call them Source Reliability and Information Reliability.

In this case I'd expect to be able to record:

Source Reliability
{char 1}
{initial value: F}
{valid values: A B C D E F}

Information Reliability
{char 1}
{initial value: 6}
{valid values: 1 2 3 4 5 6}

But so far have not been able to find somewhere to record this information against an attribute in a class.

I can see type and initial value, but cannot find a location for valid values...

Is it necessary to create a tagged value for each attribute where I wish to record this kind of information or am I missing an obvious dialog somewhere?

[AndyJ]

Digging further, I've found an attribute in the EA example project:

Rent:RentPerDay which contains a constraint:
AllowableValues{80,150,100}

However, even if I use that method, I haven't been able to find a way to make that (embedded) constraint visible to someone working with the model...

[Geert Bellekens]

Andy,

What you are describing are enumerations.
Search the help file for enumeration.

Geert

[sargasso]

AndyJ,

If the "someones" working with the model can't or won't read a constraint then I can lend you a (reasonably) blunt bread-knife (or a chainsaw) that you could use to convince them that there is a wealth of information beyond the pretty pictures ... and they'd better dam'n well read 'em.

yours in the hope of a better future for all of that do describe constraints
bruce

[AndyJ]

While I share your pain, it may be one of those theory vs. practice problems.

Developers are often under a lot of pressure, and it may be unreasonable to expect them to drill down to lower levels of a model to check for the existence of things, that 99.9999% of the time do not exist.

For this reason, I usually "externalise" constraints so that they appear on the class diagram, even if it is exported as a "pretty picture".

This also makes it easier to keep the users in the loop...

 

[KP]

If you put the constraint on the class rather than the attribute, the constraint can be shown on the diagram.

Alternatively, you can give the developers the documentation not the model - then the attribute level constraints won't be out of sight.

[AndyJ]

OK. If I am reading correctly... This is the UML way of describing the limited list of values for these two attributes.



Can anyone confirm this?

[Geert Bellekens]

Andy,

The attributes type's should not be char(1), but "Source Reliability" or "Information reliability".
The associations are not necessary.
(you can draw a dependency if you want to graphically show the relation)

Geert

[AndyJ]

OK.

Like this?



Thanks Geert,

Much appreciated.

Andy.

[Geert Bellekens]

Yep, like that.

Geert