Is it impossible to use Generics dynamically? [duplicate]

Question

I need to create at runtime instances of a class that uses generics, like class<T>, without knowing previously the type T they will have, I would like to do something like that:

public Dictionary<Type, object> GenerateLists(List<Type> types)
{
    Dictionary<Type, object> lists = new Dictionary<Type, object>();

    foreach (Type type in types)
    {
        lists.Add(type, new List<type>()); /* this new List<type>() doesn't work */
    }

    return lists;
}

...but I can't. I think it is not possible to write in C# inside the generic brackets a type variable. Is there another way to do it?

Answer 1

You can't do it like that - the point of generics is mostly compile-time type-safety - but you can do it with reflection:

public Dictionary<Type, object> GenerateLists(List<Type> types)
{
    Dictionary<Type, object> lists = new Dictionary<Type, object>();

    foreach (Type type in types)
    {
        Type genericList = typeof(List<>).MakeGenericType(type);
        lists.Add(type, Activator.CreateInstance(genericList));
    }

    return lists;
}