如何使用字符串委托订阅的2种方法 [英] How to use string delegate subscribed to 2 methods

问题描述

我有2个C#类，其中一个有一个字符串委托，另一个则向该委托订阅了一个函数.

I have 2 C# classes one of them has a string delegate and the other subscribes an function to that delegate.

我的问题是我想从委托中组合两个被调用的字符串函数，而不是随机选择它们之间的返回值

My question is I want to combine the two called string functions from the delegate instead of choosing the return value between them randomly

delgatesystem.cs:

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:

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.

note: the delgatesave.cs is attached to 2 gameobjects.

推荐答案

首先，使用非无效委托创建事件是一种反模式.事件通常与可能有更多订阅者一起使用.

First of all, creating events with non-void delegates is an antipattern. Events are typically used with potentially more subscribers.

如果有多个订阅者调用了一个非无效的多播委托，则总是返回最后一个订阅方法的返回值.

If a non-void multicast delegate is invoked with multiple subscribers, always the return value of the last subscribed method is returned.

但是毕竟，您可以执行以下操作:

But after all you can do something like this:

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

但是，更好的解决方案是使用更多常规事件:

However, a better solution would be to use more conventional events:

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

然后在您的课堂上:

public event EventHandler<PopulateNamesEventArgs> MyEvent;

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

发票:

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);
}

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