gistfile1.cs

class Blaat {
  private TaskCompletionSource<Pion> _pionCompletion = new TaskCompletionSource<Pion>();
  
  private void PionKlik(Pion item)
  {
    _pionCompletion.TrySetResult(item);
  }
  //spel.cs
  public async Task<Pion> KiesPion(Func<Pion, bool> mogelijk)
  {   
      while (true)
      {
          var pion = await _pionCompletion.Task;
          _pionCompletion = new TaskCompletionSource<Pion>();
          if (mogelijk(pion))
              return pion;
      }
  }
}