C#

public static Type MakeTypeForColumns(string typeName, MarketRecObjects.ImportFileFormatColumnDefinitionCollection columns)
{
    Type columnType = null;

    TypeBuilder columnTypeBuilder = GetTypeBuilder(typeName);


    if (null != columnTypeBuilder)
    {
        foreach (ImportFileFormatColumnDefinition col in columns)
        {
            // Create the backing field for the property
            FieldBuilder colFieldBuilder = columnTypeBuilder.DefineField(MakeValidObjectCodeName(@"_" + col.ColumnName),
                col.GetTypeForContentType(), FieldAttributes.Private);

            // Create the property itself
            PropertyBuilder colPropertyBuilder = columnTypeBuilder.DefineProperty(MakeValidObjectCodeName(col.ColumnName),
                PropertyAttributes.None, col.GetTypeForContentType(),
                Type.EmptyTypes);

            // and make a setter/getter for the property
            MethodBuilder colGetMethodBuilder = columnTypeBuilder.DefineMethod(@"get_" + colPropertyBuilder.Name, MethodAttributes.Public | MethodAttributes.HideBySig | MethodAttributes.SpecialName, colFieldBuilder.FieldType, Type.EmptyTypes);
            ILGenerator colGetMethodGenerator = colGetMethodBuilder.GetILGenerator();
            // return colField
            colGetMethodGenerator.Emit(OpCodes.Ldarg_0);
            colGetMethodGenerator.Emit(OpCodes.Ldfld, colFieldBuilder);
            colGetMethodGenerator.Emit(OpCodes.Ret);

            MethodBuilder colSetMethodBuilder = columnTypeBuilder.DefineMethod(@"set_" + colPropertyBuilder.Name, MethodAttributes.Public | MethodAttributes.HideBySig | MethodAttributes.SpecialName, typeof(void), new Type[] { colFieldBuilder.FieldType });
            ILGenerator colSetMethodGenerator = colSetMethodBuilder.GetILGenerator();
            // set colField = value
            colSetMethodGenerator.Emit(OpCodes.Ldarg_0);
            colSetMethodGenerator.Emit(OpCodes.Ldarg_1);
            colSetMethodGenerator.Emit(OpCodes.Stfld, colFieldBuilder);
            colSetMethodGenerator.Emit(OpCodes.Ret);

            colPropertyBuilder.SetGetMethod(colGetMethodBuilder);
            colPropertyBuilder.SetSetMethod(colSetMethodBuilder);

        }
        // Create an empty constructor for the class
        ConstructorBuilder columnConstructorBuilder = columnTypeBuilder.DefineConstructor(MethodAttributes.Public,
            CallingConventions.Standard,
            Type.EmptyTypes);
        // Create the constructor body...
        ILGenerator constructorGenerator = columnConstructorBuilder.GetILGenerator();
        constructorGenerator.Emit(OpCodes.Ret);

        columnType = columnTypeBuilder.CreateType();
    }
    else
    {
        columnType = ModuleBuilder.GetType(MakeValidObjectCodeName(typeName), false , false ) ;
    }
    return columnType;
}

private static TypeBuilder GetTypeBuilder(string newTypeName)
{
    if (ModuleBuilder.GetType(MakeValidObjectCodeName(newTypeName), false, true) == null)
    {
        try
        {
            TypeBuilder ret = ModuleBuilder.DefineType(MakeValidObjectCodeName(newTypeName), TypeAttributes.Public | TypeAttributes.Sealed);
            return ret;
        }
        catch (System.ArgumentException argEx)
        {
            // We have a duplicate type name....
            System.Diagnostics.Trace.TraceError(argEx.ToString());
            return null;
        }
    }
    else
    {
        return null;
    }
}

class MonthRec
{
string month_text;
string month_value;
}

private void run_code()
{
List<MonthRec> MonthList = new List<MonthRec>();
MonthList.Add(new MonthRec(){month_text = "January 2009", month_value = "012009"});
}