Community
Participate
Working Groups
Package org.eclipse.ui.operations class OperationHistoryActionHandler#getAdapter(Class adapter) is an implementation of org.eclipse.core.runtime.IAdaptable#getAdapter(java.lang.Class). It is my expectation that the above method returns an instance of the adapter class passing in as argument. However, the implementation actually compares the adapter class with interface IUndoContext, IProgressMonitor, IWorkbenchWindow and IWorkbenchPart. In my specific case, we passed a subclass of IUndoContext and expected the "undoContext" instance, but received null as our subclass is not equal to IUndoContext.class. ================================================ Example Problem: >>if (adapter.equals(IUndoContext.class)) { >> return undoContext; >>} ================================================ Could be somethings like: if ((undoContext != null) && (adapter.equals(undoContext.class))) { return undoContext; } ================================================
The adapters are meant to support adaptation to a well known interface for another object. In this case, it's IUndoContext. Examples of the adaptations I was able to find are all adapter.equals(IUndoContext.class) or adapter==IUndoContext.class. Some implementations of getAdapter(*) go to the workbench adapter factories, which would allow other plugins to register unknown adapters at runtime (like your sublcass). You will have to adapt to IUndoContext and then check with instanceof and downcast. BTW: checking for undoContext.class would prevent IUndoContext adaptation and your subclass of IUndoContext, since undoContext.class would equal the implementation class of undoContext, not any interfaces it implements. Later, PW
> BTW: checking for undoContext.class would prevent IUndoContext adaptation and > your subclass of IUndoContext, since undoContext.class would equal the > implementation class of undoContext, not any interfaces it implements. The comparing with undoContext.class is actually coded in OperationHistoryActionHandler#getAdapter(Class adapter), and as you commented, it is not working as intended. Would something like: "adapter instanceof IUndoContext" works ? thank you
This one might have been fixed as part of bug 156581.
The recommended pattern is to use "instanceof IUndoContext" rather than "adapter.equals(IUndoContext.class)". This is what we do in Util.getAdapter().
Actually, this is not a bug, but for my mistakes. Close as invalid.
