Question

I want to use dynamic ExpandoObjects for a project I’m working on, but it doesn’t compile with what I think is the correct configuration.

From what I can see Mono supports the dynamic keyword and ExpandoObject, so I am assuming it is either a configuration issue or somehow it’s not possible in Mono for Android.

When I try to use it though, I get the following error messages in Visual Studio 2010:

Error 3 One or more types required to compile a dynamic expression cannot be found. Are you missing references to Microsoft.CSharp.dll and System.Core.dll? D:\HMI\ExpandoTest\ExpandoTest\Activity1.cs 34 17 ExpandoTest

Error 1 Predefined type ‘Microsoft.CSharp.RuntimeBinder.Binder’ is not defined or imported ExpandoTest

Here is the simple test code:

using System;
using System.Dynamic;
using System.Collections.Generic;
using System.Runtime;

using Android.App;
using Android.Content;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.OS;

namespace ExpandoTest
{
    [Activity (Label = "ExpandoTest", MainLauncher = true, Icon = "@drawable/icon")]
    public class Activity1 : Activity
    {
        protected override void OnCreate (Bundle bundle)
        {
            base.OnCreate (bundle);

            // Set our view from the "main" layout resource
            SetContentView (Resource.Layout.Main);

            // Test the expando stuff
            TestExpando();
        }

        private void TestExpando()
        {
            dynamic obj = new ExpandoObject();
            int x = 10;
            obj.x = x;    // This line and the next one generate compiler errors
            obj["X"] = x;
        }
    }
}

Answer 1

As the compiler error message states, you need to add a reference to the Microsoft.CSharp assembly in order to use the dynamic keyword: