IOC containers and IDisposable

Question

It was recommended to me that, when using an IOC container, I should change this:

class Foobar: IFoobar, IDisposable {};

Into this:

Answer 1

Deriving an interface from IDisposable is in my opinion a design smell that indicates a Leaky Abstraction. As Nicholas Blumhardt put it:

an interface [...] generally shouldn't be disposable. There's no way for the one defining an interface to foresee all possible implementations of it - you can always come up with a disposable implementation of practically any interface.

Consider why you want to add IDisposable to your interface. It's probably because you have a particular implementation in mind. Hence, the implementation leaks into the abstraction.

An DI Container worth its salt should know when it creates an instance of a disposable type. When you subsequently ask the container to release an object graph, it should automatically dispose the disposable components (if their time is up according to their lifestyles).

I know that at least Castle Windsor and Autofac does this.

So in your case, you should keep your type like this:

class Foobar: IFoobar, IDisposable {};

You may find Nicholas Blumhardt's post The Relationship Zoo interesting as well - particularly the discussion about Owned<T>.