Finding out if a type implements a generic interface

Question

Let\'s say I have a type, MyType. I want to do the following:

1. Find out if MyType implements the IList interface, for some T.
2. If the answer to (1) is y

Answer 1

Using reflection (and some LINQ) you can easily do this:

public static IEnumerable GetIListTypeParameters(Type type)
{
    // Query.
    return
        from interfaceType in type.GetInterfaces()
        where interfaceType.IsGenericType
        let baseInterface = interfaceType.GetGenericTypeDefinition()
        where baseInterface == typeof(IList<>)
        select interfaceType.GetGenericArguments().First();
}

First, you are getting the interfaces on the type and filtering out only for those that are a generic type.

Then, you get the generic type definition for those interface types, and see if it is the same as IList<>.

From there, it's a simple matter of getting the generic arguments for the original interface.

Remember, a type can have multiple IList implementations, which is why the IEnumerable is returned.