如何为IAsyncOperation指定回调方法 [英] How to specify a callback method for IAsyncOperation

问题描述

是否可以指定在完成 async 操作之后要调用的方法?

Is it possible to specify a method to be called after finishing an async operation?

平台:C ++，Windows Phone 8

Platform : C++, Windows Phone 8

我需要实现非阻塞方法来异步发送UDP数据包.他们有我的方法:

I need to implement non-blocking method for sending UDP packets asynchronously. And them have my method:

onWriteComplete(int errorCode)

操作完成后回叫.

这是我尝试过的:

res = await asyncWrite();
onWriteComplete( res );

但是没有运气.

推荐答案

Windows Phone 8和Windows RT应用程序中的所有语言之间的异步操作都以类似的方式工作.异步操作返回IAsyncOperation结果，您可以使用该结果链接函数以在操作完成后运行.

Asynchronous operations work in similar ways across all languages in Windows Phone 8 and Windows RT applications. The asynchronous operation returns an IAsyncOperation result which you can use to chain a function to run when the operation completes.

在C ++中，您可以使用 create_task 和 task:then 函数.检查 C ++中的异步编程(Windows应用商店商店)一个例子.

In C++ you can create tasks and chain them in a way similar to C# using the create_task and task::then functions. Check Asynchronous Programming in C++ (Windows Store Apps) for an example.

该示例根据IAsyncOperation结果创建一个任务，并安排另一个任务在第一个任务完成时执行:

The sample creates a task from an IAsyncOperation result and schedules another task to execute when the first task completes:

auto deviceEnumTask = create_task(deviceOp);

// Call the task’s .then member function, and provide
// the lambda to be invoked when the async operation completes.
deviceEnumTask.then( [this] (DeviceInformationCollection^ devices ) 
{       
    for(int i = 0; i < devices->Size; i++)
    {
        DeviceInformation^ di = devices->GetAt(i);
        // Do something with di...          
    }       
}); // end lambda

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