CodingSeb.ExpressionEvaluator Expando Object

The ExpandoObject represents an object whose members can be dynamically added and removed at run time.

• It enables you to add and delete members of its instances at run time and set and get these members' values.
• It also supports dynamic binding, which enables you to use standard syntax like myObject.MyMember instead of more complex syntax like myObject.GetAttribute("MyMember").
• It is also a dictionary of properties and in CodingSeb.ExpressionEvaluator, you can use it as an object or as a dictionary.

The following example shows the basic usage of ExpandoObject.

public static void Example1()
{
    string script = @"
        dynamic customer = new System.Dynamic.ExpandoObject();
        customer.Name = ""Mark Upston"";
        customer.Age = 53;
        customer.Address = ""New York, US"";
        Console.WriteLine(""{0} is {1} years old and lives in {2}"", customer.Name, customer.Age, customer.Address);
    ";

    ExpressionEvaluator evaluator = new ExpressionEvaluator();
    Console.WriteLine(evaluator.ScriptEvaluate(script));
}

In C#, to enable late binding for an instance of the ExpandoObject class, you must use the dynamic keyword.

The ExpandoObject class also allows you to define and use methods, as shown below.

public static void Example2()
{
    string script = @"
        dynamic myObject = new ExpandoObject();

        myObject.Add = (a, b) => 
        {
            return (a + b).ToString();
        };

        Console.WriteLine(myObject.Add(13, 42));
    ";

    ExpressionEvaluator evaluator = new ExpressionEvaluator();
    Console.WriteLine(evaluator.ScriptEvaluate(script));
}