Can I cast
IInterface<MyClass>
to
IInterface<IAnother>
when MyClass implements IAnother?
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1Why do you need to do this? What specific problem are you attempting to address? – Bernard Jun 22 '11 at 15:44
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1possible duplicate of [Covariance and contravariance real world example](http://stackoverflow.com/questions/2662369/covariance-and-contravariance-real-world-example) – Daniel A. White Jun 22 '11 at 15:47
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I'm not familiar with C#, but you can in Java. Should just be something like: `(IInterface
)myInstanceOfIInterfaceWithMyClass;` – Patrick Perini Jun 22 '11 at 15:48
3 Answers
4
Yes, but only if your're using C# 4 (or beyond) and, IInterface is declared as IInterface<out T>.
This is called generic covariance, you can find more information on MSDN, or this (more formal but more understandable) introduction from Bart de Smet.
Johannes Rudolph
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This is possible in C# 4 via Covariance, provided you decorate your usage scenario correctly (ie: IInterface<out IAnother>).
Note that there are potential side effects to doing this, depending on your interface usage. I recommend reading up on Variance in Generic Interfaces for more details, but the main issue is that it's possible to get yourself into a situation where you can have runtime errors because you're giving up some type safety.
Reed Copsey
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