如何将对象转换为未知的类类型？

Question

As we know, by reflection we can create an class instance, but the type is object. Here are some sample code.

  Type type = p.GetType();
  Type keyType = type.GetGenericArguments()[0];
  Type valueType = type.GetGenericArguments()[1];

   var r = Activator.CreateInstance(typeof(SerializableDictionary<,>)
                .MakeGenericType(new Type[] { keyType, valueType })) 
                   as SerializableDictionary<? ,?>;

The SerializableDictionary is a subclass of Dictionary. Why will I have to cast this object? Because I want to add some elements into the SerilaizbleDictionary. The elements are from another dictioanry.

foreach (KeyValuePair<?, ?> kvp in d)// d is another dictionary
{
   r.Add(kvp.Key, kvp.Value);
}

How can I do this? Thank you very much.

Answer 1

If the items are coming from another Dictionary then could you not simply write a generic method and let it handle the generic typing?

private SerializableDictionary<TKey, TValue> ToSerializable<TKey, TValue>(Dictionary<TKey, TValue> source)
{
    var output = new SerializableDictionary<TKey, TValue>();

    foreach (var key in source.Keys)
    {
        output.Add(key, source[key]);
    }

    return output;
}

Answer 2

As mentioned in the comments consider casting to the IDictionary interface. Specifically the IDictionary.Add method.

Type type = p.GetType();
Type keyType = type.GetGenericArguments()[0];
Type valueType = type.GetGenericArguments()[1];

var dictionary =
    (IDictionary) Activator
        .CreateInstance(typeof(SerializableDictionary<,>)
        .MakeGenericType(new Type[] { keyType, valueType }));

foreach(var item in stronglyTypedDictionary)
{
    dictionary.Add(item.Key, item.Value);
}

For example:

// Assume dictionary is created using reflection
IDictionary dictionary = new Dictionary<string, object>();
var stronglyTypedDictionary = new Dictionary<string, object> { {"hello", null} };

foreach(var item in stronglyTypedDictionary)
{
    dictionary.Add(item.Key, item.Value);
}

Make sure that the types match between dictionary and stronglyTypedDictionary .