c#-如何形成TaskCompletionSource的集合并保持类型安全

我有一些异步方法：

// not ideal
private TaskCompletionSource<A> _tcsA;
private TaskCompletionSource<A> _tcsB;
private TaskCompletionSource<A> _tcsC;
...

public Task<A> GetAAsync() {
  _currentTask = TaskType.A;
  _tcsA = new TaskCompletionSource<A>();
  // some complex non-sync task, using http/events that ends with Complete();
  // QueueRequest?.Invoke(this, taskInfo); // raise request -- this does not return
  return _tcsA.Task;
}

public Task<B> GetBAsync() {
  _currentTask = TaskType.B;
  _tcsB = new TaskCompletionSource<B>();
  // some complex non-sync task, using http/events that ends with Complete();
  // QueueRequest?.Invoke(this, taskInfo); // raise request -- this does not return
  return _tcsB.Task;
}

public Task<C> GetCAsync() {
  _currentTask = TaskType.C;
  _tcsC = new TaskCompletionSource<C>();
  // some complex non-sync task, using http/events that ends with Complete();
  // QueueRequest?.Invoke(this, taskInfo); // raise request -- this does not return
  return _tcsC.Task;
}

// called by an external source, a http listener / processor
// this should complete the async call by the client and return results
public void Complete(Result result) {
  switch (_currentTask) {
    case TaskType.A:
      _tcsA.SetResult(new A());
      break;
    case TaskType.B:
      _tcsB.SetResult(new B());
      break;
    case TaskType.C:
      _tcsC.SetResult(new C());
      break;
  }

  _currentTask = TaskType.None;
}

为了简单起见,以上是半伪代码.我称这样的方法之一：

一个=等待服务.GetAAsync();

现在的问题是TaskCompletionSource< T>.是通用的,如果我有100种方法,则必须为每种返回类型创建一个变量.但是,由于一次只能调用一种方法,因此最好使用单个TaskCompletionSource,但不要将其键入对象(TaskCompletionSource< object>).

我不想做：

对象a =等待service.GetAAsync();

因为那将需要客户强制转换.因此,最好的解决方案是只有一个TaskCompletionSource,但以某种方式键入它.或者,也可以具有TaskCompletionSource字典.两者对我来说似乎都是不可能的.

我该如何解决？

更新：

有关我的情况的背景信息,请查看：Wrap synchronous code into async await in disconnected scenario

解决方法:

I don’t want to do object a = await service.GetAAsync() because that will need casting by the client.

不必要.保留相同的签名,但添加对ContinueWith的调用以强制转换为适当的类型：

public Task<A> GetAAsync() {
  _currentTask = TaskType.A;
  _tcs = new TaskCompletionSource<object>();
  // some complex task that ends with Complete();
  return _tcs.Task.ContinueWith(t => (A)t.Result);
}

或者,您也可以使用async / await执行相同的操作：

public async Task<A> GetAAsync() {
  _currentTask = TaskType.A;
  _tcs = new TaskCompletionSource<object>();
  // some complex task that ends with Complete();
  return (A)await _tcs.Task;
}

标签：async-await,casting,generics,taskcompletionsource,c
来源： https://codeday.me/bug/20191108/2005980.html