- Boost - lists.boost.org

Query for interest in library: reflective enum
by Nir Friedman 23 Feb '18

23 Feb '18

Hello, I recently needed a reflective enum for work (that is an enum where you can programmatically convert to and from strings, know how many enumerators there are, and iterate over all enumerators). I looked online but I didn't find anything that met my requirements. I was surprised that there wasn't one in Boost. So I'd like to see if there is interest; I wrote an implementation that I think has several nice features. The most polished existing smart enum implementation I could find was http://aantron.github.io/better-enums/. However, the enum implemented there is not a true enum; it uses a nested member of a class kind of approach. So for example, the is_enum type trait will not recognize is as an enum. You cannot use it as a non-type template parameter. I strongly think that a good generic smart enum macro should generate the exact "vanilla" enum (or enum class) declaration. My library's syntax looks like this: WISE_ENUM(Foo, BAR, (BAZ, 3)) This generates, among other things, exactly: enum Foo { BAR, BAZ=3}; I intend this as an explicit guarantee of the library that the programmer can count on. That way when Foo is used for things unrelating to reflection, the developer can be confident that there will not be any surprises. Beyond compatability with C++ facilities for enums, and minimizing surprise, another advantage of this approach is that it's guaranteed to be backwards compatible. An existing codebase with an existing enum/enum class can switch to this smart enum with very high confidence that existing code will continue to work as before. The WISE_ENUM macro, beyond generating the vanilla enum, also generates a switch-case function for to-string conversion (for maximal efficiency), and finally it generates a constexpr function that returns a std::array<std::pair<const char*, Foo>> listing all of the arrays and their string descriptions. This constexpr function, which is found via ADL, allows writing a sequence of (constexpr) variables and functions providing the rest of the desired functionality. Usage looks like this: std::cerr << "My enum's size is : " << wise_enum::size<Foo> // this is constexpr template variable auto x = wise_enum::from_string<Foo>("BAR").value(); // from_string returns an optional auto y = wise_enum::to_string(x); // y is string literal, no heap allocation My implementation (POC level) is here: https://github.com/quicknir/wise_enum. I don't yet have separate macros to cover enum/enum class/explicit/implicit backing type combinations. It's only about 100 lines of code, leaning heavily on BOOST_PP to do the heavy lifting. It requires variadic macros, and can probably target C++11 (if it doesn't already). I probably need to "comma harden" the macros for bizarre stuff like WISE_ENUM(Foo, (BAR, my_func<3,4>())). It has the limitation that the macro cannot be used inside a class (this is hard to workaround for reflective macros). It's also unclear how repeated enumeration values would be handled (enum Foo { BAR = 1, BAZ = 1}). As it stands this will cause a compilation failure in the generated switch case of the to_string function. Can discuss more in subsequent emails. One suggested feature is an is_contiguous trait. Another reasonable bit of functionality might be an is_wise_enum trait. Version 2 of this library could target enum sets. Although it's not fancy, I think this nicely covers a piece of functionality I often need, and it does so avoiding any downside compared to using a simple enum (beyond having to use macros). Hope other people will agree! Cheers, Nir

4 5

[Math] Only a fraction of the tests showing up online
by John Maddock 23 Feb '18

23 Feb '18

I assume this is an issue with the test matrix, but only about 1/3 of the Math lib tests are showing up at http://www.boost.org/development/tests/develop/developer/math.html Thanks, John. --- This email has been checked for viruses by AVG. http://www.avg.com

2 4

[gsoc18] - Similarity Between Geometries and Timeframe Question
by Aidan Nyquist 23 Feb '18

23 Feb '18

Hello, My name is Aidan Nyquist, a sophomore at North Park University. I'm currently majoring in Math and Physics, and minoring in computer science. I have been programming for about 4 years now, and have experience with a fair amount of languages (Python, C/C++, Java, LISP, Haskell, SQL, etc.). Sifting through all the GSoC projects, while fun, can be somewhat difficult. I have just found the "Similarity between geometries" project and think I am a great fit. I wish I had found it sooner though, so I could have started the evaluation test done by now. Is there a rough deadline for its submission? I'm applying for one other organization, and they had a Feb. 28 deadline. If there is a similar date, I will reluctantly not attend the Hackathon I was hoping to go to this weekend. However, if there is some buffer time, that would be great to know, so I could be at ease. Any advice is always appreciated. Thanks, Aidan Nyquist

2 1

Yap's formal review is starting now!
by Louis Dionne 23 Feb '18

23 Feb '18

Dear Boost community, The formal review of Zach Laine's Yap library starts Monday, February 5th and ends on Wednesday, February 14th. Yap is a C++14-and-later library to build expression templates. Yap uses new features introduced in C++14/17 to make the library simpler to use and compile faster than existing solutions, such as the well known Boost.Proto library. The documentation is available here: https://tzlaine.github.io/yap/doc/html/index.html The GitHub repository is available here: https://github.com/tzlaine/yap We encourage your participation in this review. At a minimum, please state: - Whether you believe the library should be accepted into Boost - Your name - Your knowledge of the problem domain You are strongly encouraged to also provide additional information: - What is your evaluation of the library's: * Design * Implementation * Documentation * Tests * Usefulness - Did you attempt to use the library? If so: * Which compiler(s)? * What was the experience? Any problems? - How much effort did you put into your evaluation of the review? All issues discussed during this review will be tracked on the library's GitHub issue tracker at https://github.com/tzlaine/yap/issues. Regards, Louis Dionne P.S.: I've been having trouble posting to this list. If this ends up being a duplicate post, let's make this one the official one.

14 107

Re: [boost] New Astronomy Library
by Pranam Lashkari 22 Feb '18

22 Feb '18

These days I was studying already available astronomy libraries in different languages. I found that "Astropy"( http://www.astropy.org/ ) is well established and it is being used in many places. Maybe one of the reasons for its success is that it is for Python. As we all know that python is one of the easiest languages to learn. Not all scientists are programmers and maybe that's why they find python and Astropy easy to use. So what I was thinking is, what if we build a similar structure to the same library? It will make things easier for those scientists who do not have much time to learn a new programming language and this will make the transition easier from python to C++. Is it a good idea? Pranam Lashkari On Mon, Feb 12, 2018 at 7:31 PM, JC Passy <jcpassy(a)gmail.com> wrote: > Dear Pranam, > > Sorry for taking so long to get back to you. > So I talked to some of my former colleagues about potential projects > related to the analysis of astronomical data. They forwarded me the > following paper which gives an example of the amount of data they are > dealing with and some solutions they have found. I think you might find it > interesting: > http://adsabs.harvard.edu/abs/2017PASA...34...38V > > I must say in terms of concrete ideas, they did not have anything specific > to suggest. Most of these large surveys have already teams dedicated to > develop a pipeline to deal with their specific data. However, we will keep > looking and talking to people, may be something will come up in the future. > > In the meantime, you seem to already have ideas for amateur astronomers. I > suggest you start with it (I am happy to help you if you feel like it) and > I will let you know if a potential project for professionals comes up. Does > it sound good to you? > > Cheers, > > Jean-Claude > > > On 26. Jan 2018, at 12:17, JC Passy <jcpassy(a)gmail.com> wrote: > > Dear Pranam, > > Sure, I am waiting for some feedback from two former colleagues of mine on > that matter. I should get something by early next week, I will let you know > as soon as I do. > > Cheers, > > Jean-Claude > > On 25. Jan 2018, at 13:49, Pranam Lashkari <plashkari628(a)gmail.com> wrote: > > Dear Jean-Claude; > > As you mentioned in your emails, you are having some ideas what can be > implemented in this library as per requirement of professionals in this > field. > Can you start discussing those ideas so that we can get a better idea of > how to structure this library? > > On Mon, Jan 22, 2018 at 1:40 AM, JC Passy <jcpassy(a)gmail.com> wrote: > >> Dear Pranam, dear Vinicius, >> >> not sure that my initial email made it to the mailing list. If it did, >> sorry for repeating myself. >> I am working as a computer scientist at the MPI for Intelligent Systems >> in Tübingen. Before that, I did my PhD in astrophysics and a postdoc. In >> general, I am also interested in using boost and developing a library that >> could be used by astronomers and astrophysicists. >> >> Looking at your proposal, I would second Vinicius’ opinion in the sense >> that one should try to make it a bit more specific. In particular, you >> should emphasize the *why* (what do you wish to accomplish? why would >> someone need/use it?) and the *who* (who is your target audience?). >> Regarding the latter, I see two options: >> >> 1) *amateur astronomers*: I personally do not know what their needs are, >> but I could try to find out. There are some open source projects dedicated >> to amateur astronomers (for instance https://openphdguiding.org to which >> we contributed), so that could be an option; >> >> 2) *professional astronomers*: I think a lot can be done, in particular >> regarding observational data analysis. They used *REALLY* old tools >> (IDL, IRAF, …) and given the future and upcoming surveys that will produce >> very large amount of data, they might have serious performance issues. This >> is why I believe they might benefit from using cutting-edge C++ libraries. >> >> I would be quite interested in option 2, and it could impact potentially >> a large audience IMHO. Of course, the “selling” part won’t be easy (people, >> especially astrophysicists :) won’t give up their old methods easily even >> though the new method is 10x faster) but we can facilitate this process by >> pin-pointing features that they really need. I will try to talk to some of >> my former colleagues this week and see what they think about that. In this >> case, this is a project that would need a bit of time to be properly >> defined and the deadline for GSoC18 is coming too soon. As far as I am >> concerned, this is no problem as this project does not need to be tied to >> it. >> >> Cheers, >> >> Jean-Claude >> >> >> On 21. Jan 2018, at 15:00, Vinícius dos Santos Oliveira via Boost < >> boost(a)lists.boost.org> wrote: >> >> 2018-01-21 8:07 GMT-03:00 Pranam Lashkari <plashkari628(a)gmail.com>: >> >> I have made this proposal for this new library(check attachment) >> Suggestions are invited. >> >> >> You need to focus more on "selling your project". Why is it important to >> have such library in C++ specifically? Isn't this one of those projects >> where other languages will do just fine? What market are we missing by not >> having this library? What C++ have to offer to make such library be >> inviting to write in C++? >> >> You mention "gather information from observation data". Does this mean >> you'll include a parser for some format? >> >> Can you compare this library with some non-C++ library and detail a little >> how will scope between the two differ (e.g. your library will focus >> initially only on X given the library is only starting)? >> >> For now, this should be good. When it's time to submit the student form >> through the GSoC platform, you'll also focus on selling yourself. I'll >> give >> more feedback on this when the time comes. Don't worry. >> >> Should I publish this on the wiki page of Boost GSoC 2018? >> >> >> >> Yes, please. You can put my name as a potential mentor. >> >> -- >> Vinícius dos Santos Oliveira >> https://vinipsmaker.github.io/ >> >> _______________________________________________ >> Unsubscribe & other changes: http://lists.boost.org/mailman >> /listinfo.cgi/boost >> >> >> > > >

3 4

[gsoc18] SafeFloat or Real
by Thomas Ferrand 21 Feb '18

21 Feb '18

Hello everyone, I'm a student willing to be part of this year GSoC program and I'd love to work with Boost. Among the proposed projects, I'm interested in two of them, Boost.SafeFloat and Boost.Real. As Damian Vicino is said to be the potential mentor of both, I already send him an email but don't have any answer for now. I've already made the competency test for Boost.SafeFloat but I don't know what to do now, wait for an answer? Seek another mentor? Can you please guide me? Thanks, Thomas Ferrand

2 1

new to the organization
by Rajat Miglani 21 Feb '18

21 Feb '18

Dear boost community, I am a GSOC aspirant and I'd like to contribute to your organization. I have read the project ideas and is interested in working on:- 1)Boost.SafeFloat or 2)Enhancing Boost.Intrusive Library Can I get some more info about how to work on these projects and the basic requirements so that I can learn them and be able to contribute to my fullest. Thank you,

2 1

Legal problem with Stackoverflow contribution under the "Creative Commons Attribution Share Alike 3.0" license
by Dominique CHABAUD 21 Feb '18

21 Feb '18

Hi all, In Boost 1.62.0 we saw in the following header file : boost/thread/win32/thread_primitives.hpp that the function inline ticks_type __stdcall GetTickCount64emulation() is a contribution coming from https://stackoverflow.com /questions/8211820/userland-interrupt-timer-access-such- as-via-kequeryinterrupttime-or-similar Stackoverflow re-lisensing to MIT is told to be in place starting Feb 1, 2016 and only for new contributions. But the StackOverflow contribution that has been borrowed in Boost is Nov 23, 2011 and contributions prior to Feb1, 2016 are under the "Creative Commons Attribution Share Alike 3.0" license which is not permissive. This causes legal problem. Hope somebody can fix this. Thanks Dominique

15 37

Re: [boost] C++03 / C++11 compatibility question for compiled libraries
by Glen Fernandes 21 Feb '18

21 Feb '18

Olaf van der Spek wrote: > > Glen Fernandes wrote: >> Before I became a contributor to Boost, and before I became a Boost >> library author, I was a user of Boost at Microsoft. Even as late as >> 2014 when I left the company, those projects depended on Boost for >> C++03 support. (In fact, at least one of the projects only dropped >> C++03 support as late as 2016). > > Where did the C++03 support requirement come from though, an old compiler? > Even VS 2010 knows some C++11 stuff. Supporting teams that were still on older compilers was the motivation, yes. Boost was upgraded more frequently than upgrading to a newer compiler (even though in this particular case, the compiler was developed within the same company). For that project I referenced which dropped C++03 support in 2016, they also dropped VC10 support in the same year. Those projects came to depend on the reliability of Boost for its implementation of standard library facilities that were otherwise defective in VC that wouldn't be fixed until the next major release of the compiler, while Boost releases were every few months. Even trivial standard library things like std::ref, std::addressof, std::unique_ptr::~unique_ptr (wrong order of operations in VC10, fixed in VC11), std::align (wrong return value in VC11, fixed in VC12), std::call_once (was 1500 times slower than InitOnceExecuteOnce, fixed in VC14), the list went on. After a while, certain projects that dropped compatibility still chose to use Boost instead of the corresponding [now fixed] standard library facilities, just operating under the assumption that Boost would provide a higher quality of implementation, and more rapid rate of maintenance. Glen

2 1

failing accumulators tests
by Yuval Lifshitz 21 Feb '18

21 Feb '18

Dear All,Did anyone seen these failures on p_square_cumul_dist and weighted_median (latest checkout from github and gcc7.3.1/fedora27)? libs/accumulators/test/p_square_cumul_dist.cpp(66): error: in "p_square_cumulative_distribution test/test_stat": difference{0.0331329} between 0.5 * (1.0 + my_erf( histogram[i].first / std::sqrt(2.0) )){0.010331329148570989} and histogram[i].second{0.01} exceeds 3%libs/accumulators/test/p_square_cumul_dist.cpp(66): error: in "p_square_cumulative_distribution test/test_stat": difference{0.0372556} between 0.5 * (1.0 + my_erf( histogram[i].first / std::sqrt(2.0) )){0.020755484496021825} and histogram[i].second{0.02001} exceeds 3% libs/accumulators/test/p_square_cumul_dist.cpp(66): error: in "p_square_cumulative_distribution test/test_stat": difference{0.0326898} between 0.5 * (1.0 + my_erf( histogram[i].first / std::sqrt(2.0) )){0.030980693519017} and histogram[i].second{0.029999999999999999} exceeds 3% libs/accumulators/test/p_square_cumul_dist.cpp(66): error: in "p_square_cumulative_distribution test/test_stat": difference{0.0306804} between 0.5 * (1.0 + my_erf( histogram[i].first / std::sqrt(2.0) )){0.041227215128245343} and histogram[i].second{0.040000000000000001} exceeds 3% libs/accumulators/test/weighted_median.cpp(50): error: in "weighted_median test/test_stat": difference{0.0327894} between 1.{1} and weighted_median(acc_dens){0.96825159071079681} exceeds 3% libs/accumulators/test/weighted_median.cpp(51): error: in "weighted_median test/test_stat": difference{0.0316788} between 1.{1} and weighted_median(acc_cdist){0.96929395242297978} exceeds 3% Best Regards, Yuval

1 0