DynamicDictionary

using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Dynamic;
using System.Linq;

namespace Core.Dynamic {

    /// <summary>
    /// DynamicObject class used to allow dynamic operations on a <see cref="IDictionary<string,object>"/> Dictionary
    /// </summary>
    public sealed class DynamicDictionary:DynamicObject {

        readonly Func<IDictionary<string,object>> _dataThunk;
        readonly bool _ignoreIfMemberNotfound;

        public DynamicDictionary(Func<IDictionary<string,object>> dataThunk,bool ignoreIfMemberNotfound = false) {
            _dataThunk = dataThunk;
            _ignoreIfMemberNotfound = ignoreIfMemberNotfound;
        }

        IDictionary<string,object> Data {
            get {
                IDictionary<string,object> viewData = _dataThunk();
                Debug.Assert(viewData != null);
                return viewData;
            }
        }

        // Implementing this function improves the debugging experience as it provides the debugger with the list of all
        // the properties currently defined on the object
        public override IEnumerable<string> GetDynamicMemberNames() {
            return Data.Keys.Cast<string>();
        }

        public override bool TryGetMember(GetMemberBinder binder,out object result) {

            if(_ignoreIfMemberNotfound) {
                if(!Data.Keys.Contains(binder.Name)) {
                    result = null;
                    return true;
                }
            }

            result = Data[binder.Name];

            // since ViewDataDictionary always returns a result even if the key does not exist, always return true
            return true;
        }

        public override bool TrySetMember(SetMemberBinder binder,object value) {
            Data[binder.Name] = value;
            // you can always set a key in the dictionary so return true
            return true;
        }
    }
}