MethodInfo from ExpandoObject

Question

I know that it was asked for Reflection on ExpandoObjects here before.

My question is a little different. I have static and dynamic functions which should be executed from some function similar to object ExecuteFunction(string name, params object[] parameters).

I execute the static functions via Reflection. So the question is, if I can reuse the MethodInfo call and get a MethodInfo object from the ExpandoObject? Or do I have to implement 2 functions (One with Action and one with MethodInfo)?

Answer 1

You won't get any MethodInfo for the dynamically defined methods on an ExpandoObject.
Dynamically defined methods are the same as dynamically defined properties, they just happen to be of a delegate type.

However, this delegate type contains a property named Method of type MethodInfo which you can utilize:

object ExecuteFunction(IDictionary<string, object> obj, string name,
                       params object[] parameters)
{
    object property;
    if(!obj.TryGetValue(name, out property))
        return null;

    var del = property as Delegate;
    if(del == null)
        return null;

    var methodInfo = del.Method;

    // do with methodInfo what you need to do to invoke it.
    // This should be in its own method so you can call it from both versions of your
    // ExecuteFunction method.
}

Please note that the first parameter is of type IDictionary<string, object>. ExpandoObject implements this interface, and we need no other features from ExpandoObject, so the parameter is just of the type of the implemented interface we need the functionality of.

Answer 2

The opensource framework ImpromptuInterface (available from nuget), provides easy access to the DLR calls that let you call methods by a string name. The only catch is if the method returns void you have to use InvokeMemberAction and if it returns a value you can use InvokeMember. This allows you to invoke methods that are dynamically defined, and calls statically defined methods faster than reflection.