Re: [boost] future<>::then() Error returning future<void> (on trunk)

Subject: Re: [boost] future<>::then() Error returning future<void> (on trunk)
From: Fernando Pelliccioni (fpelliccioni_at_[hidden])
Date: 2013-04-03 22:41:09

On Mon, Apr 1, 2013 at 2:09 PM, Vicente J. Botet Escriba <
vicente.botet_at_[hidden]> wrote:

> Le 22/01/13 22:56, Vicente Botet a écrit :
>
>  Fernando Pelliccioni wrote
>>
>>> Hi Vicente, hi all,
>>>
>>> I noticed that in the trunk  there is a implementation of
>>> future<>::then().
>>> Thank you very much for your efforts to implement it!
>>>
>> Hi Fernando,
>>
>> I have started with a restricted implementation. While trying to cover
>> with
>> the whole requirements I didn't reach to get correct implementation. This
>> is
>> way this new feature is not delivered yet. For the time been I don't think
>> the current implementation is ready for production code.
>>
>>
>>  The following example, compiles OK
>>>
>>>      boost::future
>>> <int>
>>>   f1 = boost::async([]() { return 123; });
>>>      f1.then([](boost::future
>>> <int>
>>>   const& f) {
>>>              return std::string("");
>>>      });
>>>
>>>
>>> But this one fails to compile:
>>>      boost::future
>>> <int>
>>>   f1 = boost::async([]() { return 123; });
>>>      f1.then([](boost::future
>>> <int>
>>>   const& f) {
>>>      });
>>>
>>> Here future<>::then() have to returns future
>>> <void>
>>>   like ...
>>>
>>>        boost::async([]() {  });
>>>
>>> Am I right?
>>>
>> Yes, it should. I have no access to my development environment for this
>> week. Could you post the compiler error?
>>
>>
>>  On the other hand, have you taken into account the following paper?
>>>      http://www.open-std.org/jtc1/**sc22/wg21/docs/papers/2012/**
>>> n3451.pdf<http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3451.pdf>
>>>
>> I read it and the mail exchanges related to this paper.
>> Currently I didn't reached to make it working at all when the future
>> destructor blocks, but I'm not  sure this is the hidden problem as I have
>> also other issues when the future destructor doesn't blocks.
>>
>> I'm really sorry that the current state is not really usable :(
>>
>>  Hi Fernando,
>
> I have reworked the future::then function, and even if it is not yet
> complete (e.g. deferred is not implemented for c++98 compilers) it start to
> be usable for c++11 compilers, even if BOOST_THREAD_DONT_PROVIDE_**FUTURE_INVALID_AFTER_GET
> is not defined. BTW, joining on the async future destructor works also.
>
> Please could you give it a try and let me know whatever you can find that
> doesn't works as you expect,
>
> Best,
> Vicente
>
>
Thanks Vicente,

I will see it tomorow !!!

Thanks again!

Best,
Fernando

>
>
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