如何声明和等待异步委托？

Question

出于某种原因，尽管这个问题在我的谷歌搜索中出现了很多，但我似乎找不到真正的答案。也许我只是用错了代表，我不确定。如果是 X-Y 问题，我很高兴有其他处理方法。

说我有这个：

public class SomeLibrary
{
    public delegate void OnSomethingHappened(EventInfo eventInfo);
    public OnSomethingHappened onSomethingHappened;
    
    public void SomeMethod()
    {
        // ...
        
        // Something happened here, so we'd better trigger the event
        onSomethingHappened?.Invoke(eventInfo);
        
        // ...
    }
}

public class MyCode
{
    public void SomeInitialisationMethod()
    {
        SomeLibrary someLibrary = new SomeLibrary();
        someLibrary.onSomethingHappened += SomeEventHandler;
    }
    
    private void SomeEventHandler(EventInfo eventInfo)
    {
        DoSyncProcessing(eventInfo);
    }
}

应该没问题（除了愚蠢的错别字）。

现在想象一下，我的常规同步 DoSyncProcessing 函数突然变得异步，就像在这个神奇的非函数代码中一样：

public class SomeLibrary
{
    public async delegate Task OnSomethingHappened(EventInfo eventInfo); // <<< IDK what I'm doing here!
    public OnSomethingHappened onSomethingHappened;
    
    public void SomeMethod()
    {
        // ...
        
        // Something happened here, so we'd better trigger the event
        await onSomethingHappened?.Invoke(eventInfo);                            // <<< IDK what I'm doing here either!
        
        // ...
    }
}

public class MyCode
{
    public void SomeInitialisationMethod()
    {
        SomeLibrary someLibrary = new SomeLibrary();
        someLibrary.onSomethingHappened += SomeEventHandler;
    }
    
    private async Task SomeEventHandler(EventInfo eventInfo)
    {
        await DoAsyncProcessing(eventInfo);
    }
}

我该如何处理？这样做的正确方法是什么？

Answer 1

async 修饰符影响方法实现，而不是签名。所以改变这个：

public async delegate Task OnSomethingHappened(EventInfo eventInfo);

到这里：

public delegate Task OnSomethingHappened(EventInfo eventInfo);

你的代码就可以工作了。