协同程序的执行代码是什么?有什么用处？有什么缺点?

function Start() {

// - After 0 seconds, prints "Starting 0.0"

// - After 0 seconds, prints "Before WaitAndPrint Finishes 0.0"

// - After 2 seconds, prints "WaitAndPrint 2.0"

// 先打印"Starting 0.0"和"Before WaitAndPrint Finishes 0.0"两句,2秒后打印"WaitAndPrint 2.0"

print ("Starting " + Time.time );

// Start function WaitAndPrint as a coroutine. And continue execution while it is running

// this is the same as WaintAndPrint(2.0) as the compiler does it for you automatically

// 协同程序WaitAndPrint在Start函数内执行,可以视同于它与Start函数同步执行.

StartCoroutine(WaitAndPrint(2.0));

print ("Before WaitAndPrint Finishes " + Time.time );

function WaitAndPrint (waitTime : float) {

// suspend execution for waitTime seconds

// 暂停执行waitTime秒

yield WaitForSeconds (waitTime);

print ("WaitAndPrint "+ Time.time );

作用：一个协同程序在执行过程中,可以在任意位置使用yield语句。yield的返回值控制何时恢复协同程序向下执行。协同程序在对象自有帧执行过程中堪称优秀。协同程序在性能上没有更多的开销。

缺点：协同程序并非真线程，可能会发生堵塞。