[news.eclipse.modeling.gmf] Re: How to forbid changing an attribute valu

[Boris Blajer <boris.blajer@xxxxxxxxxxx>]

Hi Alexander,

There is a way how to consistently make it impossible to set an 
attribute no matter how the change is attempted. You will need to 
register a ResourceSetListener to the transactional editing domain of 
your diagram. In #transactionAboutToCommit() method, check if the change 
is allowed and, if not, throw a RollbackException.

Note that although DiagramEventBrocker is meant to be a centralized 
place for dispatching notifications for a diagram editing domain, you 
may not throw exceptions from a NotificationPreCommitListener, so this 
cannot be used for transaction validation.

Best regards,
Boris


Alexander Dotor wrote:
> Hello,
>
> I want to forbid the setting of an attribute value via the property 
> sheet depending on the state of my semantic model.
>
> As far as I can see it is not possible to replace the SetCommand as it 
> is working directly on the model. I tried to install an EditPolicy as 
> EditPolicyRoles.PROPERTY_HANDLER_ROLE, EditPolicyRoles.SEMANTIC_ROLE or 
> even EditPolicy.DIRECT_EDIT_ROLE. If I debug into the creation of the 
> SetCommand it seems to be indepent of any EditPolicy.
>
> What can I do now?
>
> Why is using the PropertyView not calling the getBeforeSetCommand of an 
> EditHelper for example?
>
> Currently I have to adapt different startegies for implementing my 
> dynamic constraints for every kind of command. Why is the edit helper 
> offering all these methods if they aren't used? This is very annoying.
>
> Cheers,
> Alexander