向动态类型添加值会导致RuntimeBinderException

Question

I am working on building a UITypeEditor (launched from the property grid) to edit a Dictionary<T,T> where T could be any scalar type ( int , long , double , string , DateTime , etc.). The dictionary to be edited is passed into the control as an object named innerobject . I get the type and key-value types as following:

Type t = innerobject.GetType();
Type[] member_t = innerobject.GetType().GetGenericArguments();
if(member_t.Length !=2)
    return null;

var keyconverter = TypeDescriptor.GetConverter(member_t[0]);
var valueconverter = TypeDescriptor.GetConverter(member_t[1]);

if (null == keyconverter || null == valueconverter)
    return null;

var dic = Activator.CreateInstance(t);

dynamic dyndic = dic;

Later when I try to add values to it, I do the following (s is one line in the textbox):

string[] str = s.Split(new char[] { ',', ' ', '\t' }, StringSplitOptions.RemoveEmptyEntries);
if (str.Length == 2)
{
    object a = keyconverter.ConvertFromString(str[0]);
    object b = valueconverter.ConvertFromString(str[1]);
    dyndic[a] = b;
}

A Microsoft.CSharp.RuntimeBinder.RuntimeBinderException is thrown at this point.

A first chance exception of type 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in Unknown Module.
Additional information: The best overloaded method match for 'System.Collections.Generic.Dictionary<double,double>.this[double]' has some invalid arguments. If there is a handler for this exception, the program may be safely continued.

Answer 1

You need a and b to be dynamic also:

dynamic a = keyconverter.ConvertFromString(str[0]);
dynamic b = valueconverter.ConvertFromString(str[1]);
dyndic[a] = b;