不能使用create_async()与WRL WinRT组件 [英] Can't use create_async() with WRL WinRT component
问题描述
我想使用WRL编写一个具有async支持的WinRT组件,但我发现 create_async()
是未定义的,即使我包括 ppltask.h
和使用命名空间并发
如何使用WRL模式创建后台任务?
I want to write a WinRT component with async support using WRL, but I found create_async()
is undefined even I included the ppltask.h
and using namespace concurrency
How to create a background task with WRL pattern?
我的功能如下:
HRESULT GetStreamAsync([out, retval] IAsyncOperation<IRRandomAccessStream*>** operation);
我也尝试使用 IThreadPoolStatics-> RunAsync c $ c>,但似乎它只能在
IAsyncAction
的情况下使用,并且没有返回值。有人可以帮助吗?
I also try to use IThreadPoolStatics->RunAsync()
, but seems it only can be used in case of IAsyncAction
and without return value. Does anyone can help?
推荐答案
concurrency :: create_async
仅在C ++ / CX中可用(这可能未在文档中明确说明,但所有可能的返回类型都是帽子类型,表明它只能在C ++ / CX中使用)。
concurrency::create_async
is only usable in C++/CX (this may not be expressly stated in the documentation, but all of the possible return types are hat types, indicating it is only usable in C++/CX).
WRL包括 Microsoft :: WRL :: AsyncBase
基类模板,您可以从中导出以使用C ++和WRL实现异步操作。
WRL includes the Microsoft::WRL::AsyncBase
base class template, which you can derive from to implement asynchronous operations using C++ and WRL.
我不知道一个规范的实现,包括 std :: future
或 concurrency :: task
,但您可以在Boost授权的 CxxReflect库(搜索 async_operation_base
和 task_based_async_operation
)。
I don't know of a canonical implementation that wraps std::future
or concurrency::task
, but you can find an example of an implementation in the Boost-licensed CxxReflect library (search for async_operation_base
and task_based_async_operation
).
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