Re: [boost] [thread] boost::future::then

Le 09/10/15 15:44, Vladimir Prus a écrit :

On 09-Oct-15 4:02 PM, Mikael Olenfalk wrote:

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On Fri, Oct 9, 2015 at 9:43 AM, Vladimir Prus wrote:

...

In particular, suppose I have this:

// Thread 1

boost::promise<int> pi; boost::future<int> fi = pi.get_future();

// pass pi to thread 2 somehow

fi.then(....);

// Thread 2

pi.set_value(100);

And I want continuation to be executed in thread 1, assuming that thread 1 runs Qt event loop, allowing me to use QTimer::singleShot, or queued signal, or similar mechanism. How would I go about making boost::future do it? Has anybody done so?

... I might have misunderstood the question but I would assume a solution would be to build boost.thread with executors enabled[1]. And then wrap the QT event loop in an executor interface[2] and use the boost::future<T>::then(Executor&, ...) overload.

Mikael,

thanks for the response. I suppose it would work - although if I need to pass this executor any time I call 'then', it become rather awkward rather quickly. Well this is the current interface :) It would be nicer if promise could have an executor, and pass it to future and then to futures returned by 'then', so that I only need to to specify custom behaviour when creating a promise - that can be easily wrapped in a function. If your future is created with auto f = async(ex, fct)

then the call to f.then(fct2); would use the same executor ex. "When the scheduler or launch policy is not provided the continuation inherits the parent's launch policy or scheduler. "

Do you have any comments on presence or absence of bugs, and overall API maturity? Having to define macros to get useful functionality is not quite perfect.

I agree, but that is life. I have blocked the interface since version 3. You must request any additional features explicitly if you want them, or just say you want to use a higher version BOOST_THREAD_VERSION 4 Vicente Vicente