我想我发现了 RescueAttribute 被破坏的情况。或者我可能不正确地使用协同程序。
我有一个这样的 ViewModel:
[Rescue("Rescue")]
class MyViewModel
{
//... left out some bus-logic code here ...
public void Login()
{
yield return Show.Busy();
//the following line will also cause the problem, just like AsyncResult
//yield return Show.MessageBox("Test");
yield return new AsyncResult(() => _server.Login());
//throw new Exception("Aww, snap!");
yield return Show.NotBusy();
}
public void Rescue(Exception exc)
{
//Show a messagebox or something
}
}
AsyncResult 是这样实现的:
using Exec = Caliburn.PresentationFramework.Invocation.Execute;
public class AsyncResult : IResult
{
private readonly Action _function;
public AsyncResult(Action function)
{
_function = function;
}
public void Execute(ResultExecutionContext context)
{
Exec.OnBackgroundThread(delegate
{
try
{
_function();
}
catch (Exception exc)
{
Exec.OnUIThread(() => Completed(this, new ResultCompletionEventArgs { Error = exc, WasCancelled = true }));
return;
}
Exec.OnUIThread(() => Completed(this, new ResultCompletionEventArgs()));
});
}
public event EventHandler<ResultCompletionEventArgs> Completed = delegate { };
}
如果我在上面的 ViewModel 中取消注释异常,Rescue 将无法处理异常。
这是 Caliburn 中的错误,还是 AsyncResult 实施错误?
如果您在 yield 之前放置一个异常以返回 AsyncResult,Rescue 就可以正常工作。此外,如果在异步线程上引发异常,救援仍然有效!
编辑:您也可以使用 Show.MessageBox 而不是 AsyncResult 来重现相同的问题。