使用抽象类型参数将对象转换为IList

Question

In my code, I have an object:

object obj = ...

Which I know is of type MyListType, where MyListType is a subclass of IList and T is a subclass of MyAbstractClass. The type parameter of MyListType is constrained so that it is always a subclass of MyAbstractClass.

However, trying to cast obj

MyListType<MyAbstractClass> myList = (MyListType<MyAbstractClass>)obj;

gives a runtime error.

I tried to define an explicit operator

public static explicit operator MyListType<MyAbstractClass>(MyListType<T> list)
{
    MyListType<MyAbstractClass> newList = new MyListType<MyAbstractClass>();
    foreach(T t in list)
        newList.Add((MyAbstractClass) t);
    return newList;
}

However, this operator doesn't get used by the cast since obj is an object, not a MyListType. Is there a workaround to successfully perform this cast?

I've looked at this question , but their the list was of an unknown type.

Answer 1

I ended up reworking my code so that I wouldn't have to do this, but the solution is to first cast it to an IEnumerable, and then add the IEnumerable to a list.

MyListType<MyAbstractClass> list = new MyListType<MyAbstractClass>();
IEnumerable<MyAbstractClass> enumerable = obj as IEnumerable<MyAbstractClass>;
list.AddRange(enumerable);