如何使用字符串委托订阅 2 种方法

How to use string delegate subscribed to 2 methods

我有 2 个 C# 类 其中一个有一个字符串委托,另一个订阅了该委托的函数。

我的问题是我想组合委托中调用的两个字符串函数,而不是随机选择它们之间的 return 值

delgatesystem.cs:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class delegatesystem : MonoBehaviour {

public delegate string MyDelegate();
public static event MyDelegate MyEvent;
string GameObjectsNames = "";

void Update ()
{
    if (Input.GetKeyDown(KeyCode.Space))
    {
        if (MyEvent != null)
         {
           GameObjectsNames +=  MyEvent();
         }
       }
    }
}

delegatesave.cs:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class delegatesave : MonoBehaviour {

void Start ()
{
    delegatesystem.MyEvent += DelegateFunction;
}

string DelegateFunction()
{
    return gameObject.name;
}
}

注意: delgatesave.cs 附加到 2 个游戏对象。

首先,使用非空委托创建事件是一种反模式。事件通常用于潜在的更多订阅者。

如果使用多个订阅者调用非空多播委托,则最后订阅方法的 return 值总是 returned。

但毕竟你可以这样做:

string[] objectNames = MyEvent.GetInvocationList().Cast<MyDelegate>().Select(del => del()).ToArray();

但是,更好的解决方案是使用更常规的事件:

public class PopulateNamesEventArgs : EventArgs
{
    private List<string> names = new List<string>();
    public string[] Names => names.ToArray();
    public void AddName(string name) => names.Add(name);
}

然后在你的 class:

public event EventHandler<PopulateNamesEventArgs> MyEvent;

protected virtual void OnMyEvent(PopulateNamesEventArgs e) => MyEvent?.Invoke(this, e);

调用:

var e = new PopulateNamesEventArgs();
OnMyEvent(e);
string[] objectNames = e.Names; // the result is now populated by the subscribers

订阅:

void Start()
{
    delegatesystem.MyEvent += DelegateFunction;
}

void DelegateFunction(object sender, PopulateNamesEventArgs e)
{
    e.AddName(gameObject.name);
}