Question

我正在尝试创建一个使用BackgroundWorker在Winforms程序中异步分配的方法。

void Assign<T>(Func<object> method, ref T obj)
{
    var bw = new BackgroundWorker();
    bw.DoWork += 
        (object sender, DoWorkEventArgs e) => 
            e.Result = ((Func<object>)(e.Argument))();
    bw.RunWorkerCompleted += 
        (object sender, RunWorkerCompletedEventArgs e) =>
            obj = (T)e.Result; // Error here
    bw.RunWorkerAsync(method);
}

Assign(slowMethodReturnsFloat, ref aFloatVariable);
Assign(slowMethodReturnsDataSet, ref aDataSetVar);

然而，我得到了错误：

“不能在lambda表达式中使用ref或out参数”

实现它的任何其他方式？任何不使用BackgroundWorker的方法？

Answer 1

考虑传递lambda而不是ref作为第二个参数：

void Assign<T>(Func<object> method, Action<T> objSetter)
{
    var bw = new BackgroundWorker();
    bw.DoWork += 
        (object sender, DoWorkEventArgs e) => 
            e.Result = ((Func<object>)(e.Argument))();
    bw.RunWorkerCompleted += 
        (object sender, RunWorkerCompletedEventArgs e) =>
            objSetter((T)e.Result);
    bw.RunWorkerAsync(method);
}

Assign(slowMethodReturnsFloat, ret => aFloatVariable = ret);
Assign(slowMethodReturnsDataSet, ret => aDataSetVar = ret);

Answer 2

我不确定T是什么，但另一种选择可能是传递回调：

void Assign<T>(Func<object> method, Action<T> callBack);

void callBack(T result)

通用异步分配

2 个答案: