Eclipse plugin development - e4 part with input: instantiate input - eclipse

Question

Eclipse 4 does not have any notion of an editor, only parts. So how do we receive the file for our "editor" parts? I'm talking about an e4 equivalent of the IEditorPart.init method, and the IEditorInput it receives.
I've stumbled upon this example by Tom Schindl. He is able to inject the input in the part constructor. For the input object to be available for injection, it has to be instantiated in the IEclipseContext somehow. This article refers to Schindl's example, and leads me to consider the following approach: intercept "Open file" commands (if they exist) from the Eclipse platform, create an input instance for the "editor" part and put it in the context (IEcpliseContext.set(class, value)), and open the part with the EPartService.
So the question is: is this the right approach to creating an e4 "editor"? And is it possible to implement?

Answer 1

It is easier to put the input data in the part's transient data since it is tricky to get the data injected at the right point.
For something that behaves like an editor you will probably use a Part Descriptor so that you can create multiple parts from the single descriptor.
You would create the part using something like:
#Inject
EPartService partService;
// Create from part descriptor
MPart part = partService.createPart("part descriptor id");
// Set input in transient data
part.getTransientData().put("inputKey", inputData);
// Add to part stack
MPartStack partStack = ... stack you want to use
partStack.getChildren().add(part);
// Show
partService.showPart(part, PartState.ACTIVATE);
In your part code you get the transient data by injecting the MPart. For example in the constructur:
#Inject
public MyClass(MPart myPart)
{
Object input = part.getTransientData().get("inputKey");
....
}