MongoDB.Bson.Serialization.BsonMemberMap.GetFieldSetter C# (CSharp) Метод

        private Action<object, object> GetFieldSetter()
        {
            var fieldInfo = (FieldInfo)_memberInfo;

            if (IsReadOnly)
            {
                var message = string.Format(
                    "The field '{0} {1}' of class '{2}' is readonly. To avoid this exception, call IsReadOnly to ensure that setting a value is allowed.",
                    fieldInfo.FieldType.FullName, fieldInfo.Name, fieldInfo.DeclaringType.FullName);
                throw new BsonSerializationException(message);
            }

            var sourceType = fieldInfo.DeclaringType;
            var method = new DynamicMethod("Set" + fieldInfo.Name, null, new[] { typeof(object), typeof(object) }, true);
            var gen = method.GetILGenerator();

            gen.Emit(OpCodes.Ldarg_0);
            gen.Emit(OpCodes.Castclass, sourceType);
            gen.Emit(OpCodes.Ldarg_1);
            gen.Emit(OpCodes.Unbox_Any, fieldInfo.FieldType);
            gen.Emit(OpCodes.Stfld, fieldInfo);
            gen.Emit(OpCodes.Ret);

            return (Action<object, object>)method.CreateDelegate(typeof(Action<object, object>));
        }