如何使用动态回调？

本文介绍了如何使用动态回调？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我一直收到此错误，不确定如何纠正

I keep getting this error and not sure how to correct it

错误1无法将回调用作动态参数分派的操作，因为它是一个方法组。您是否打算调用该方法？

Error 1 Cannot use 'Callback' as an argument to a dynamically dispatched operation because it is a method group. Did you intend to invoke the method?

//... if (e.Status == LiveConnectSessionStatus.Connected) { client = new LiveConnectClient(e.Session); LiveOperationResult operationResult = await client.GetAsync("me"); try { dynamic meResult = operationResult.Result; var openId = meResult.id; var email = meResult.emails.preferred; //MessageBox.Show(openId); //MessageBox.Show(email); userService.SignIn(openId, email, Callback); } catch (LiveConnectException exception) { MessageBox.Show("Error calling API: " + exception.Message); } } } private void Callback(ErrorModel error) { if (error != null) { MessageBox.Show(error.FriendlyErrorMsg, error.Caption, MessageBoxButton.OK); } else { } } public void SignIn(string id, string email, Action<ErrorModel> callBack) { }

推荐答案

问题在于此调用是动态的：

The problem is that this call is dynamic:

userService.SignIn(openId, email, Callback);

必须是，因为 openId 和电子邮件推断为动态类型：

It has to be, because openId and email are inferred to be of type dynamic:

var openId = meResult.id; var email = meResult.emails.preferred;

在动态调用中不能使用这样的方法组转换-这只是其中之一限制使用 dynamic 。

You can't use a method group conversion like this in a dynamic call - it's just one of the restrictions of using dynamic.

因此，选项：

• 给出 openId 和 email 显式类型，如果（ userService 不是动态的 ）将使调用变为非动态的，方法组转换将在此调用进行。这只是意味着要明确指定类型，因为 dynamic 有一个隐式转换：

• Give openId and email explicit types, which (if userService isn't dynamic) will make the call non-dynamic, at which the method group conversion will work. This just means specifying the types explicitly, as there's an implicit conversion available from dynamic:

string openId = meResult.id; string email = meResult.emails.preferred; userService.SignIn(openId, email, Callback);

从<$ c创建一个特定的委托类型实例$ c>回调方法，如果要保持 SignIn 调用动态：

Create a specific delegate type instance from the Callback method, if you want to keep the SignIn call dynamic:

var openId = meResult.id; var email = meResult.emails.preferred; // Or use whichever delegate type is actually appropriate for SignIn userService.SignIn(openId, email, new Action<ErrorModel>(Callback));