call method at runtime

I found this at reflection eamples

 // get all public static methods of MyClass type
  MethodInfo[] methodInfos = typeof(MyClass).GetMethods(BindingFlags.Public |
                                                  BindingFlags.Static);


[C#]
// dynamically load assembly from file Test.dll
 Assembly testAssembly = Assembly.LoadFile(@"c:\Test.dll");

[C#]
// get type of class Calculator from just loaded assembly
Type calcType = testAssembly.GetType("Test.Calculator");

[C#]
// create instance of class Calculator
object calcInstance = Activator.CreateInstance(calcType);

[C#]
// get info about property: public double Number
PropertyInfo numberPropertyInfo = calcType.GetProperty("Number");

[C#]
// get value of property: public double Number
double value = (double)numberPropertyInfo.GetValue(calcInstance, null);

[C#]
// set value of property: public double Number
numberPropertyInfo.SetValue(calcInstance, 10.0, null);

[C#]
// get info about static property: public static double Pi
PropertyInfo piPropertyInfo = calcType.GetProperty("Pi");

[C#]
// get value of static property: public static double Pi
double piValue = (double)piPropertyInfo.GetValue(null, null);

[C#]
// invoke public instance method: public void Clear()
calcType.InvokeMember("Clear",
BindingFlags.InvokeMethod | BindingFlags.Instance | BindingFlags.Public,
null, calcInstance, null);

[C#]
// invoke private instance method: private void DoClear()
calcType.InvokeMember("DoClear",
BindingFlags.InvokeMethod | BindingFlags.Instance | BindingFlags.NonPublic,
null, calcInstance, null);

[C#]
// invoke public instance method: public double Add(double number)
double value = (double)calcType.InvokeMember("Add",
BindingFlags.InvokeMethod | BindingFlags.Instance | BindingFlags.Public,
null, calcInstance, new object[] { 20.0 });

[C#]
// invoke public static method: public static double GetPi()
double piVal