Description Pierre-Charles David 2014-04-09 04:53:01 EDT

The DRefreshable type, defined in viewpoint.ecore, provides a single refresh() method. It is implemented by DView, all concrete DRepresentation and DRepresentationElement classes, and a lot of code seems to exist solely to support the implementation if these refresh methods.

The problem is that this implementation seems completely parallel to the main refresh algorithms (for example DDiagramSynchronizer), and I doubt it correctly implements all the subtleties needed for a correct refresh (handling of mapping imports and reuses, representation extensions, layers, conditional styles, style feature customizations, etc. etc.).

From what I could  gather, all this mechanics only exists for historical reasons, when the refresh/synchronization logic was spread over all the representation elements types instead of centralized in the D*Synrchronizer classes. It had the nice property of supporting partial refresh on only a sub-set of a representation, but at this point it has not been actively maintained for years, and it's not clear if it works, or even if it is ever called in normal operation.

More concrete details:
* When called on a DRepresentation, DRefreshable.refresh() actually delegates to DialectManager.refresh(), so this case is fine, although redundant.
* When called on a DRepresentationContainer, it refreshes all its valid representations (see the point above), and also removes all the ones with no/invalid target. That may be a valid operation, but it could be implemented without exposing an API in the metamodel.
* For all the concrete DRepresentationElement types, each has its own refresh logic, which in most cases look like a simplified (and thus probably broken) version of what the global D*Synchronizers do.

Further investigation is needed (hence this ticket), but it looks like quite a lot of code could be removed and/or simplified if indeed we can remove DRefreshabe.refresh().