Atributes:
//can add metadata in program, It store with the program
//using ILDasm to check atributes

//usage
[CodeReviewAttribute("08/08/2005", "Allan Zhang",
Comment = "That is a Attribute test")]
class Employee {}

//define target and atr
[AttributeUsage(AttributeTargets.Class |
AttributeTargets.Constructor |
AttributeTargets.Interface |
AttributeTargets.Method |
AttributeTargets.Field |
AttributeTargets.Property,
AllowMultiple=true)]
class CodeReviewAtrribute : System.Attribute
{
private string reviewDate;
private string reviewerName;
private string reviewComments;
...
}

Reflections: //look the metadata in program, discory, late binding

//Display attribute in Code
System.Reflection.MemberInfo inf = typeof(Employee);
object[] atributes = inf.GetCustomAttributes(false);
foreach (object attribute in attributes)
{
CodeReviewAttribute attr = (CodeReviewAttribute) attribute;
Console.WriteLine("This is code was reviewed on {0} by {1} \n Comments {2}",
attr.date,
attr.name,
attr.comment )
}

//Discovery
Assembly asm = Assembly.Load("Mscorlib.dll");
Type[] types = asm.GetTypes();
foreach(Type type in types)
{
Console.WriteLine("Type is{0}, type);
Console.WriteLine("\n{0} types found." types.Length);
}

//LateBinding
Type mathType =Type.GetType("System.Math");
object obj = Activator.CreaterInstance(mathType);

Type[] parameterTypes = new Type[2];
parameterTypes[0] = Type.GetType("System.Double");
parameterTypes[1] = Type.GetType("System.Double");
MethodInfo powInfo = mathType.GetMethod("Pow", parameterTypes);

object[] parameters = new object[2];
parameters[0] = 5;
parameters[1] = 3;
object returnValue = powInfo.Invoke(obj, parameters);
Console.WriteLine("5 to the 3rd power is {0}, returnValue);

Thread:
//Create Implicit Threads

using System.Threading
Thread threadOne = new Thread(new ThreadStart(Countup));
Thread threadTwo = new Thread(new ThreadStart(Countup));
threadOne.Name = "Thread One";
threadTwo.Name = "Thread two";
threadOne.Start();
threadTwo.Start();

//Joining & killing Threads
//join two threads in current threa
threadOne.start();
threadTwo.Start();
threadOne.Join();
threadTwo.Join();
//this will print, after two above two threads ends
Console.WriteLine("The other threads done");
//sleep(millisenconds)
threadOne.sleep(1);
threadOne.Abort();

Synchronization:
//1. no conflict between threads
interlocked.Increment(ref synchValue);
//2. lock method, this will block other thread when it enter into it
lock(this)
{
int temp = synchValue;
temp++;
Thread.Sleep(2);
synchValue = temp;
synchValue = temp;
Console.WriteLine("{0} Count up: {1}",
Thread.CurrentThread.Name,
synchValue);
}