GEF：如何使用预定义的第三方模型将域信息与表示信息分开？

Question

I am in the process of developing a GEF View (which will later be evolving into a GEF Editor ), and I'm doing so with the help of the GEF Book .

In chapter 8.1 ("GEF Models") in the book, a model is constructed which mixes Domain Information and Presentation Information (which is generously admitted): GenealogyElement is the abstract superclass for the rest of the model objects (but one).

GenealogyElement takes care of the location, and location changes of its subclasses ( Person , Marriage ) and the like, which themselves include the actual domain information. Btw, the source code can be found on the books website .

I wouldn't mind doing so myself (even if this is probably "bad style"), but I'm using a third-party model which I cannot alter , ie, I cannot change the class ThirdPartyNode to extend, say, ExampleElement .

One option would of course be to write my own model against the third-party one, create an abstract class ExampleElement , and let a new class ExampleNode extend both ExampleElement and ThirdPartyNode . I might end up doing so, but really want to include different possibilities first, as creating another model is a lot of typing, and potentially superfluous (isn't it?).

What are my options for seperating both information types?

Thanks in advance!

Answer 1

I solved a similar problem creating a different model containing the presentation data (ie: the position of the element) and a reference to the actual data model. You only shoud consider carefully how the data model notifies its changes to the editor.