[News.eclipse.technology.gmf] Re: Building a diagram programmatically

["dzh" <dzhpingbo@xxxxxxxx>]

As it mentioned below "override CreationEditPolicy.getCreateCommand(request) 
for the editpolicy which will be installed on your EditPart " by Alex, which 
role should be used according to REQ_CREATE?

"Alex Shatalin" <vano@xxxxxxxxxxx> дÈëÏûÏ¢ÐÂÎÅ:drd6fb$mlu$1@xxxxxxxxxxxxxxxxxxxx
> Hi, Nikolay!
>    Concerning creation several domain and notation model elements I can 
> suggest you to try to understand how it works now by debugging the code 
> generated by GMF. ;-) Here are some ideas which will help you understand 
> key points in the generated + runtime code:
>
>    For the creation/deletion of domain model elements, we have a separate 
> EditPolicy - *ItemSemanticEditPolicy. This EditPolicy contains methods 
> "getCreateCommand(CreateElementRequest req)" and 
> "getDestroyElementCommand(DestroyElementRequest req)". It is important 
> that getCreateCommand method should exists in an EditPolicy which 
> corresponds with the an element (installed for the corresponding EditPart) 
> there you would like to create new one. For example, if you have to create 
> something on diagram, getCreateCommand of diagram's 
> *ItemSemanticEditPolicy have to be modified in accordance. 
> getDestroyElementCommand() should be located in an EditPolicy corresponds 
> to the element you would like to destroy. In case of node on the diagram, 
> on pressing "del" on this node, getDestroyElementCommand() of 
> *ItemSemanticEditPolicy installed on Node editpart will be called.
>
>    Concerning creation of view (notation) model elements, it is not so 
> clear for me. I can see that CreationEditPolicy of an element will 
> redirect control from getCommand() method to 
> getCreateElementAndViewCommand() one. In getCreateElementAndViewCommand() 
> first of all, semanticCommand will be created. This command will be 
> created in accordance with the logic which I've described above. In other 
> words, this command will wrap command returned by corresponding 
> *ItemSemanticEditPolicy. On the next step, viewCommand will be created by 
> calling getCreateCommand(request). AFAIU, viewCommand will wrap all 
> command which should create notation model elements. You can see that 
> getCreateCommand() method of this editpolicy just creates new 
> CreateCommand() for each CreateViewRequest.ViewDescriptor from the 
> request. So, to achieve your goal you have to put several 
> CreateViewRequest.ViewDescriptor into the create request.
>
>    Finally, I think you have two options: either override 
> CreationEditPolicy.getCreateCommand(request) for the editpolicy which will 
> be installed on your EditPart or by putting several ViewDescriptors into 
> CreateViewRequest and it is a bit more tricky - you have to override 
> CreateUnspecifiedTypeRequest.createRequests() finally for the specific 
> palette tool.
>
>    I'm not sure that there is no other ways to achieve this goal in 
> runtime, but I hope runtime team will correct me if I've missed something.
>
> -- 
> Alex Shatalin
>