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Re: [boost] [gsoc16] Can I quickly check if the below really is the best approach?
by Shangtong Zhang 16 Jan '16

16 Jan '16

Hi, > // At global scope, allocates no memory whatsoever > static const constexpr static_map<int, const char *> map { > { 5, "apple" }, > { 8, "pear" }, > { 0, "banana" }, > ... > }; > // Works, constexpr "apple" > constexpr const char *what_is_5 = map[5]; > // Works > assert(map[5] && !strcmp(map[5], "apple"); > // Works > map[5]="orange"; > assert(map[5] && !strcmp(map[5], "orange"); > // Throws exception as there is no key 6 > map[6]; > map.at <http://map.at/>(6); I have difficulty understanding this, As variable map is const and constexpr, how can map[5]=“orange” work? I don’t know how to implement this, where to store the “orange”. Could anyone help me? Thanks, Shangtong Zhang, Senior Student, School of Computer Science, Fudan University, PRC.

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[gsoc16]Interest in static map
by Shangtong Zhang 15 Jan '16

15 Jan '16

Hi Niall Douglas, I’m interested in the project static map and want to contribute to it in gsoc 2016. And I try to start with the programming competency test. Following is what I have done, https://github.com/ShangtongZhang/StaticMap/blob/master/main.cpp <https://github.com/ShangtongZhang/StaticMap/blob/master/main.cpp> Could you please give me some advice? In addition, I’m a little confused with // This should fail elegantly and usefully ... //constexpr std::array<unsigned, 0> string_hashes_fail = hash_strings(5); My understanding is that it will raise a run-time exception, is it right? Thanks, Shangtong Zhang, Senior Student, School of Computer Science, Fudan University, PRC.

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Is there interest in Computable Calculus?
by Damian Vicino 15 Jan '16

15 Jan '16

Hi, I’m interested in developing basic support of “real numbers” for computable calculus applications. In computable calculus, reals have infinite precision (certain restrictions may apply). The usual approach is representing numbers as functions producing digits. An arithmetic operation produces a new function using the functions in the operands and some simple expression manipulations. When a number needs to be evaluated (e.g., for comparisons where expression rules are unknown), enough digits for reaching an answer are generated using the functions. For example, 3.14 < pi requires generating 3 digits to answer “true”. The algorithms for arithmetic operations and evaluation are well known, and multiple implementations were developed (mostly in the 90s). However, I couldn’t find an open source implementation and had to come up with my own for working in a project during the last 2 years. My preferred reference for the required algorithms is the book: Aberth, Oliver. Computable Calculus. Academic Press, 2001. In particular, my initial scope would be the 4 arithmetic operations (+, -, *, /), and the comparison operators (<, =) for reals. Someone is interested in such a library in boost?

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IS THERE A WAY TO FIND IF A CERTAIN TYPE HAS A CERTAIN MEMBER?
by Juan Dent 15 Jan '16

15 Jan '16

> HI, > > > I have read that via enable_if and other constructs, one can declare a member of a type conditionally. > > What I need is a way to be able to test whether a certain type has a certain method or member data, so that I can call it or use it accordingly. > > Does boost have something like this?? > > > Regards, > Juan

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a safe integer library
by Robert Ramey 14 Jan '16

14 Jan '16

Arithmetic operations in C++ are NOT guaranteed to yield a correct mathematical result. This feature is inherited from the early days of C. The behavior of int, unsigned int and others were designed to map closely to the underlying hardware. Computer hardware implements these types as a fixed number of bits. When the result of arithmetic operations exceeds this number of bits, the result will not be arithmetically correct. I have crafted a library to address this issue once and for all. You can find out more about this by checking out the page for Safe Numerics at the boost library incubator. www.blincubator.com I hereby request that this library be added to the boost review queue. I've also made a proposal for the C++ Standards committee to include a simplified version of this library as part of he C++ standard. You can see the proposal at http://www.rrsd.com/software_development/safe_numerics/proposal.pdf Robert Ramey

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ATTENTION: Library requirements..
by Rene Rivera 13 Jan '16

13 Jan '16

Last Summer I brought up the subject of library organization requirements to make it easier to write the development and release tools needed to keep the Boost machine going. See this thread < http://lists.boost.org/Archives/boost/2015/06/223027.php> for a refresher. This morning I committed the first part of the above.. A new set of library requirements that take into account existing practices. Adds some additional integration requirements. And puts in limits to reduce some integration burdens. Please read the new requirements carefully < http://www.boost.org/development/requirements.html#Requirements>. It would be wonderful if authors start making changes as needed immediately. But at some point I, and possible others, will start making changes to all libraries to follow the requirements. So that the release, build, and testing teams can move forward with better support. And of course, more cleanups and such will follow. Hopefully before the next release is out the door. -- -- Rene Rivera -- Grafik - Don't Assume Anything -- Robot Dreams - http://robot-dreams.net -- rrivera/acm.org (msn) - grafikrobot/aim,yahoo,skype,efnet,gmail

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[BPM] Supporting an alternative to meta/libraries.json
by Louis Dionne 13 Jan '16

13 Jan '16

Dear list, Currently, all Boost libraries are required to have a meta/libraries.json file at their root, which contains some meta-data describing the library. As I understand it, this meta-data is then used to generate the list of all libraries with their description when a release is done. I find having such a directory at the root of every library annoying, since it clutters it. Furthermore, for metaprogramming libraries, the name can be slightly confusing since meta/ might be expected to contain something different. I propose that we allow libraries to specify their metadata in a `.boost` file located at their root. Using a dotfile is the most common way of providing information for an external service (for example .travis.yml), and dotfiles are usually more discrete when viewing the project in an editor. Furthermore, making `boost` part of the filename is more descriptive. I have submitted a pull request to BPM [1] adding the ability to fetch the meta data in a .boost file. The meta-data can still be provided in meta/libraries.json, so this should not affect existing libraries. Related questions that we might want to consider: - Should it be .boost.json instead of .boost? - Perhaps we could store the meta-data for all the libraries in the same place, and get rid of the individual meta-data files? - If this suggestion is accepted, is there more to modify than BPM? Regards, Louis [1]: https://github.com/boostorg/bpm/pull/1

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[test] BOOST_TEST macro and std::max
by Benedek Thaler 13 Jan '16

13 Jan '16

Hi, I'd expect the following cheks to pass: BOOST_TEST(3u == (std::max)(0u, 3u)); BOOST_TEST(3u == ((std::max)(0u, 3u))); But both fails with: check 3u == ((std::max)(0u, 3u)) has failed [3 != 7095312] Did I miss something regarding BOOST_TEST usage? Platform: Linux, GCC 5.3, Boost 1.60 Thanks, Benedek

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Re: [boost] asio config.hpp macro redefinition - mistake?
by Curdeius Curdeius 13 Jan '16

13 Jan '16

> > ---------- Wiadomość przekazana dalej ---------- > From: "John M. Dlugosz" <mpbecey7gu(a)snkmail.com> > To: boost(a)lists.boost.org > Cc: > Date: Tue, 12 Jan 2016 17:32:48 -0600 > Subject: [boost] asio config.hpp macro redefinition - mistake? > In file boost_1_59_0\boost\asio\detail\config.hpp line 227 gives a macro > redefinition warning. > (...) > It seems that this is missing a guard or has the if/else things mixed up. > This was fixed some time ago. See https://github.com/boostorg/asio/commit/b9cb61416e1972d7490d91da91df549703f… . Regards, Marek Kurdej

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[fusion]enabler.hpp junk character at start of file
by Aparna Kumta 13 Jan '16

13 Jan '16

All accumulator tests fail when compiled with Oracle Solaris Studio in 'dev' branch as follows: "../boost/fusion/support/detail/enabler.hpp", line 1: Error: A declaration was expected instead of "???". 1 Error(s) and 1 Warning(s) detected. See http://www.boost.org/development/tests/develop/developer/output/oracle-spar… It appears that in file boost/fusion/support/detail/enabler.hpp, there is some junk character at the start of file. This cannot be observed via vi editor, but with ' head -1 enabler.hpp', this can be seen. % head -1 enabler.hpp ��/*===================================== Perhaps these characters should be removed? When I view the file on github, I do not see the issue, however when I try to edit the file, I see it. Will submit a PR. Thanks, Aparna

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