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Editorial Team
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Asked: 2026-06-07T06:00:04+00:00

I used InheritedExport attribute, and have a tree of objects. Think IMessageSender where I

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I used InheritedExport attribute, and have a tree of objects. Think IMessageSender where I have SmtpSender, TextSender, HttpPostSender. But through decorator pattern I have additional classes that also inherit this MEF InheritedExport attribute.

However when composing the senders, I do not want to decorators to be composed.
Now Lazy could help, whereas I only retrieve the objects that are not of the Decorator type. But I can’t ask Lazy what T actually is. Perhaps metadata could help, but the metadata only applies to the object that has this metadata. I don’t want to force implementers (read: developers) to add the correct metadata to their decorator or sender.

Any ideas? Thanks!

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1 Answer

  1. Editorial Team

    I needed to do something similar. In the end I opted to add metadata that gave me the required information, but I can see why that’s not ideal for your.

    One other possibility would be to switch from using an automatic import via attributes, and explicitly call CompositionService.GetExports instead. Then you’d end up with an IEnumerable of Export objects. This would let you get at the contract name (usually, but not always, the type name) and the contract metadata. I think that the contract metadata always includes the type name, so you’d have the information you’re looking for.

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