unity 利用协程做定时器，这里为什么需要用静态构造函数

Question

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;

public class WaitTimeManager
{
    private static TaskBehaviour m_Task;
    static WaitTimeManager()
    {
        GameObject go = new GameObject("#WaitTimeManager#");
        GameObject.DontDestroyOnLoad(go);
        m_Task = go.AddComponent<TaskBehaviour>();
    }
    static public Coroutine WaitTime(float time, UnityAction callback)
    {
        return m_Task.StartCoroutine(Coroutine(time, callback));
    }
    static public void CencelWait(ref Coroutine coroutine)
    {
        if (coroutine != null)
        {
            m_Task.StopCoroutine(coroutine);
            coroutine = null;
        }
    }
    static IEnumerator Coroutine(float time, UnityAction callback)
    {
        yield return new WaitForSeconds(time);
        if (callback != null)
        {
            callback();
        }
    }
    public class TaskBehaviour : MonoBehaviour { }
}

Answer 1

你也可以写成单例那样，不过概念都是一样的，就是为了保证每次使用TaskBehaviour它时，都是同一个它，这样才保证了计时器的正确性。举个例子：你想要定个闹钟，然后拿起手机定了个早上8点的闹钟，过来会你想了想8点有点早改成8:10分的吧，那么此时你还是要用刚刚定闹钟的那个手机，而不是随便找个手机就可以。