判斷Action Func 是否是異步方法

// 根據委託指向的方法時候包含async標記 Method.IsDefined(async)

//通用寫法

private static bool IsAsyncAppliedToDelegate(Delegate d)
{
    return d.Method.GetCustomAttribute(typeof(AsyncStateMachineAttribute)) != null;
}




//例子: 判斷 Action 和Func<TResult>

static bool IsThisAsync(Action action)
{
    return action.Method.IsDefined(typeof(AsyncStateMachineAttribute),false);
}

static bool IsThisAsync(Func<Task> action)
{
    return action.Method.IsDefined(typeof(AsyncStateMachineAttribute),false);
}