我在哪里标记 lambda 表达式异步? [英] Where do I mark a lambda expression async?

问题描述

我有这个代码:

private async void ContextMenuForGroupRightTapped(object sender, RightTappedRoutedEventArgs args)
{
    CheckBox ckbx = null;
    if (sender is CheckBox)
    {
        ckbx = sender as CheckBox;
    }
    if (null == ckbx)
    {
        return;
    }
    string groupName = ckbx.Content.ToString();

    var contextMenu = new PopupMenu();

    // Add a command to edit the current Group
    contextMenu.Commands.Add(new UICommand("Edit this Group", (contextMenuCmd) =>
    {
        Frame.Navigate(typeof(LocationGroupCreator), groupName);
    }));

    // Add a command to delete the current Group
    contextMenu.Commands.Add(new UICommand("Delete this Group", (contextMenuCmd) =>
    {
        SQLiteUtils slu = new SQLiteUtils();
        slu.DeleteGroupAsync(groupName); // this line raises Resharper's hackles, but appending await raises err msg. Where should the "async" be?
    }));

    // Show the context menu at the position the image was right-clicked
    await contextMenu.ShowAsync(args.GetPosition(this));
}

...Resharper 的检查抱怨说，因为没有等待这个调用，所以在调用完成之前会继续执行当前方法.考虑将 'await' 运算符应用于调用的结果"(在注释行上).

...that Resharper's inspection complained about with, "Because this call is not awaited, execution of the current method continues before the call is completed. Consider applying the 'await' operator to the result of the call" (on the line with the comment).

所以，我在前面加上了一个await"，当然，我还需要在某处添加一个async"——但在哪里?

And so, I prepended an "await" to it but, of course, I then need to add an "async" somewhere, too - but where?

推荐答案

要标记 lambda 异步，只需在其参数列表前加上 async:

To mark a lambda async, simply prepend async before its argument list:

// Add a command to delete the current Group
contextMenu.Commands.Add(new UICommand("Delete this Group", async (contextMenuCmd) =>
{
    SQLiteUtils slu = new SQLiteUtils();
    await slu.DeleteGroupAsync(groupName);
}));

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