January 2017 - Boost - lists.preview.boost.org

Variadic append for std::string
by Olaf van der Spek 19 Feb '17

19 Feb '17

Hi, One frequently needs to append stuff to strings, but the standard way (s += "A" + "B" + to_string(42)) isn't optimal due to temporaries. A variadic append() for std::string seems like the obvious solution. It could support string_view (boost and std), integers, maybe floats but without formatting options.. It could even be extensible by calling append(s, t); append(s, "A", "B", 42); Would this be useful for the Boost String Algo lib? -- Olaf

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Boost.Python sandox or multiple interpreters
by David Bellot 17 Feb '17

17 Feb '17

Hi, I'm using Boost.Python to load and use plugins in Python. Each plugin can define a few functions which are are pre-determined, so that my C++ software knows what to call. However, the mistake I've made was to think that the Python interpreter could be initialized many times, so that each plugins was existing and running into a separate interpreter. It's of course not the case and therefore, each time I load a new plugin, its functions overwrite the functions of the same name from the previous plugin (the one which was loaded just before), and so on. Is there a possibility to either : - have as many independent Python interpreters at the same time ? - or encapsulate each plugin in an independent "environment" ? - or any other solution which would elegantly solve this problem ? :-D Thanks for your help, David

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[teeks] Missing winerror.h for MSVC-9
by Andrey Semashev 17 Feb '17

17 Feb '17

Hi, I see lots of tests failing on teeks99-09b-win2012R2-64on64, MSVC-9.0 because winerror.h is missing. Here's an example: http://www.boost.org/development/tests/develop/developer/output/teeks99-09b… I can see that the file is present in Windows SDK 6.0A, which is supposed to be used with this compiler. The tests are passing on my machine. Could this be a tester configuration issue? Also, all MSVC-15 tests are failing on teeks99-09o-win2012R2-64on64 with the error of 'cl' not being found.

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What is http://downloads.sourceforge.net/boost/boost_1_63_0.tar.bz2 ?
by Jonathan Wakely 14 Feb '17

14 Feb '17

The link http://downloads.sourceforge.net/boost/boost_1_63_0.tar.bz2 redirects to http://downloads.sourceforge.net/project/boost/boost/snapshots/master/boost… which seems to be a snapshot from master, and VERY different to the boost_1_63_0 release (which makes it a VERY misleading URL). How often is that snapshot updated? Shouldn't it have a different name if it's not boost_1_63_0.tar.bz2 but some completely different set of sources (which currently don't even build)? The Fedora Linux packages have been using that URL, for several years by the look of things. So I have no idea what arbitrary collection of changes we've been shipping instead of a proper release.

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[gsoc17] Attn: We need 2017 mentors and project ideas for Boost!
by Niall Douglas 07 Feb '17

07 Feb '17

Dear Boost community, We are now a few weeks from the beginning of Google Summer of Code 2017! Last year we had the big surprise of being rejected by Google as an org, the second time ever, on the basis that Google felt we needed a year off. Thanks to the quick actions of the Boost Steering Committee and IMC Financial Markets we managed to put together a "Boost Summer of Code" so the students with projects in progress would not be left stranded. Despite a fair few teething problems, I think that worked out okay. As part of filling in our application for 2017, we must supply to Google a list of potential GSoC mentors and potential GSoC projects for summer 2017 in order to be approved as an organisation this year. Therefore a lengthy page of awesome project ideas at https://svn.boost.org/trac/boost/wiki/SoC2017 before *February 9th* would be an enormous help to getting us approved again this year and bringing to Boost another US$35,000 of Google funding. If you think yourself able to mentor a student doing some work on Boost this summer, *please* consider adding a description of the proposed work item and your name to the list. The year before last we had more slots awarded to us by Google than we had good combinations of student and mentor, so we had to return slots which I believe has not happened here at Boost GSoC in at least a decade. That means that your project ideas have a better chance than ever of receiving funding if you can find a good student, and that is best done by getting project ideas floated *early*. If you want to know more about mentoring a Google Summer of Code funded student work before you nominate yourself, please feel free to ask on the main Boost developers mailing list boost(a)lists.boost.org or via gsoc-admin(a)boost.org. Thank you in advance for your time.

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[Fit] Update: Request for feedback
by Paul Fultz II 06 Feb '17

06 Feb '17

Hi, I have made a lot of updates to the Fit library based on the changes suggested during the review earlier this year. I have also improved the documentation. I have expanded on the introductory materials and have add a lot more cross-referencing. The documentation can be found here: http://fit.readthedocs.io <http://fit.readthedocs.io/> Let me know of any feedback about the library either here on the mailing list or on Github issues. Thanks, Paul

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[outcome] Feedback on parts A and B of Tutorial mk III requested
by Niall Douglas 02 Feb '17

02 Feb '17

Dear Boost, I am truly hoping that this will be the last time I ask for feedback on Outcome's tutorial as this is the third complete rewrite. Many thanks for all the feedback so far, this Mk. III tutorial wouldn't look like this without all your help. Part A is 100% on pure expected<T, E> as currently before the standards committee. It has nothing to do with Outcome, but places Outcome in context. Part B is a polemic on why people should not use arbitrary type E in expected<T, E> and instead should restrain themselves to either E = std::error_code or E = std::exception_ptr. I'm requesting feedback on parts A and B of the tutorial which I think are mostly complete now. Specific feedback on these topics is particularly welcomed: 1. I've tried to make some of the code examples in Part A less contrived. Are there any obviously specific additional things I can do (note Parts B and C have more realistic programs)? 2. Are you convinced by the end of Part B that using arbitrary types for type E is a bad idea? If not, what did I fail to do in my explanation? Many thanks in advance. Niall -- ned Productions Limited Consulting http://www.nedproductions.biz/ http://ie.linkedin.com/in/nialldouglas/

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Re: [boost] Boost XML Serialization Stability across library versions
by Adlai Shawareb 31 Jan '17

31 Jan '17

Thanks Robert, Regarding your suggestion to use text serialization. Since, over time, we will be adding and deleting data from the data set that we serialize, would the following be the right approach to managing the changes in the data that is de/serialized. I'm thinking that we would set the BOOST_CLASS_VERSION before de/serializing. { ar & mInt; If(version >= 2) ar & mFloat; If(version >= 3) ar & mInt2; ar & mFloat2; } Regards, Adlai On 1/25/17 12:04:00, Robert Ramey wrote: > Right. No one as under taken that task. Should be fairly straight > forward using spirit v3. > Robert Ramey

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[container] ::flat_map function force_copy break strict-aliasing on gcc < 4.4
by Владислав Щапов 31 Jan '17

31 Jan '17

Hello! On function: template<class D, class S> BOOST_CONTAINER_FORCEINLINE static D force_copy(S s) { D *vp = reinterpret_cast<D *>(&s); return D(*vp); } gcc 4.3.4 (SLE 11) produced wrong code. It seems that the compiler does not create a copy of an object "s" and returns an object of D(). If I change the signature of function on "BOOST_CONTAINER_FORCEINLINE static D force_copy(const S& s)" the code works and the tests pass. But then does not create a copy of an object "s" in a function call. I'm not sure that this change is correct. Is there any other workaround for this problem with a compiler gcc 4.3 or better disable strict-aliasing? -- Best regards, Vladislav

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C++Now 2017 Registration is Open
by Jon Kalb 30 Jan '17

30 Jan '17

Boost Devs, Registration for C++Now 2017 is now open: http://bit.ly/CppNow2017IsOpen The conference will be in Aspen, Colorado from May 15th to 20th. The deadline for submissions is this Friday: http://cppnow.org/2017-conference/announcements/2017/01/06/call-for-submiss… Jon

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