How to "transfer" resolved instances from a container to another?

I want to achieve the following.

1. On a worker thread, an ExportProvider resolves one single type and calls one method to retrieve data. E.g.:

var dataLoader = MiniContainer.GetExportedValue<IDataLoader>();
dataLoader.RetrieveData();

1. Meanwhile, on the UI thread, the app’s ExportProvider resolves all exported types and values. I.e. regular bootstrapping.

2. When the main container is ready, I want to “transfer” the IDataLoader instance from the worker thread. That way, the main container can load super-fast.

How can this be achieved? I guess this operation would be equivalent to “as soon as type X is resolved, call X.Foo() in a worker thread, then wait for it after bootstrapping”.

Please advise 😃

[weltkante]

Yes that works, another way to solve it is to not put IDataLoader into the catalog at all. You can have an IDataLoaderProvider in the catalog which will do all the async background stuff, and when its done it publishes the IDataLoader by making it available to others. Everyone would import the IDataLoaderProvider and access the IDataLoader through it, and you can decide how to handle “early access” (eg. blocking, async/await, events, etc.)

[AArnott]

So the basic idea is to explicitly set the value of an export

Explicitly set the value on an exporting property, yes. After which, any access to that property getter will of course return the value you set it to. That means when MEF accesses that property to get its exported value, it will get the value you set it to. It also means that if MEF accesses that property before you set it, MEF will get the default value instead and assign that to the importer that wanted it. This is the huge limitation of this air-lifting technique. You’d have to be very careful to not activate any MEF part that imports this value until the export has been set.

preventing the framework from retrieving its value from reflected constructor?

I don’t know what you mean by this. You’re not preventing the framework from anything.