Best practice: How to expose a read-only ICollection

Question

I have an ICollection called foos in my class which I want to expose as read-only (see this question). I see that the interface defines a

Answer 1

My recommendation is to return use a ReadOnlyCollection for the scenario directly. This makes the usage explicit to the calling user.

Normally I would suggest using the appropriate interface. But given that the .NET Framework does not currently have a suitable IReadOnlyCollection, you must go with the ReadOnlyCollection type.

Also you must be aware when using ReadOnlyCollection, because it is not actually read-only: Immutability and ReadOnlyCollection