November 2019 - Boost-users - lists.preview.boost.org

Boost.Numeric.Interval: Please specify rounding control mechanism
by Bastien Commelongue 01 Dec '20

01 Dec '20

Hello, I am building an app for IOS (ARM) and I had this issue while compiling: *Boost.Numeric.Interval: Please specify rounding control mechanism.* C99 version should be used in this case but __USE_ISOC99 is not defined. Modifying the condition with this code (using __cplusplus) fixed the issue: *boost/numeric/interval/hw_rounding.hpp(36)* *#if defined(BOOST_NUMERIC_INTERVAL_NO_HARDWARE) && (defined(__USE_ISOC99) || defined(__MSL__) || (defined __cplusplus && __cplusplus >= 201103L))# include <boost/numeric/interval/detail/c99_rounding_control.hpp>#endif* Let me know if I missed something or if you plan to integrate this modification in a next version. Cheers, Bastien Commelongue

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[Urgent] ./bootstrap.sh from boost_1_70_0 is failing in SunOS
by kamallochan Jena 11 Dec '19

11 Dec '19

Hi All, Thanks for your support!!! In SunOS platform, The bootstrap.sh from boost_1_70_0 failed with error " ./build.sh: syntax error at line 143: `machine=$' unexpected " Can any one look into it and kindly suggest how to fix this issue and proceed further. *It is blocking our current project build!!!* *PFB, the details:* $ uname -a SunOS kamal Generic_150401-55 i86pc i386 i86pc $ cd 3rdparty/boost/tools/build $ ls boost-build.jam bootstrap.bat CONTRIBUTING.rst example Jamroot.jam notes src bootstrap_vms.com bootstrap.sh doc index.html LICENSE.txt README.rst test $ ./bootstrap.sh -n Bootstrapping the build engine with toolset sun... Failed to bootstrap the build engine Consult 'bootstrap.log' for more details $ cat bootstrap.log ./build.sh: syntax error at line 143: `machine=$' unexpected Thanks, Kamal

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[review][fixed_string] FixedString review starts today
by Joaquin M López Muñoz 05 Dec '19

05 Dec '19

The Boost formal review of Krystian Stasiowski and Vinnie Falco's FixedString library starts today November 25 and extends up to December 4. Description FixedString provides a dynamically resizable string of characters with compile-time fixed capacity and contiguous embedded storage in which the characters are placed within the string object itself. Its API closely resembles that of std::string. Repo and docs GitHub repository: https://github.com/18/fixed_string Online docs: https://18.github.io/doc/fixed_string Review questions Here are some questions you might want to answer in your review: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? - Are you knowledgeable about the problem domain? And finally, every review should answer this question: - Do you think the library should be accepted as a Boost library? I invite you to submit your review, either publicly to the developers or the users lists, or else, if for whatever reason you don't want to go public, directly to me. Thank you for investing your time on reviewing Krystian and Vinnie's work and for contributing to the advancement of Boost. Best regards, Joaquín M López Muñoz Review manager for candidate Boost.FixedString

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Write Property Tree JSON on a single line
by aCPlusPlusDeveloper 29 Nov '19

29 Nov '19

Is it possible to force the boost::propertytree::write_json method to write the entire json tree on a single line (not human readable at all but to save file size)? Sent with [ProtonMail](https://protonmail.com) Secure Email.

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Interest in a C++20 Unit Testing Framework?
by Krzysztof Jusiak 27 Nov '19

27 Nov '19

Hi, I was wondering whether there is any interest in exploring a C++20 single header/single module, macro-free Unit Testing Framework with no dependencies? Github: https://github.com/boost-experimental/ut Additional links: - Try it online: https://godbolt.org/z/uVDxkW - Benchmarks: https://github.com/boost-experimental/ut#benchmarks - How it works?: https://github.com/boost-experimental/ut#how-it-works Thanks, Kris

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Building with CMake?
by Robert Dailey 25 Nov '19

25 Nov '19

I see that individual repositories like boostorg/filesystem on Github have a CMakeLists.txt. But the boostorg/boost super repo doesn't have a root CMakeLists.txt. Either this doesn't follow standard CMake structure or there's no way to build with CMake globally instead of bjam. How can I build the boost libraries with CMake?

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Re: [Boost-users] [boost] Interest in a C++20 Unit Testing Framework?
by Krzysztof Jusiak 24 Nov '19

24 Nov '19

I see your point, but I'm not advocating here for providing multiple ways of doing the same thing as I agree it might be confusing although I'd also argue that it's already a case with boost.test for example (single header/static/shared library or BOOST_TEST, BOOST_CHECK, BOOST_CHECK_EQ accomplish pretty much the same things but there are also a trade-offs here so it depends) Also, having a possibility for users to do so is valuable IMHO but I wouldn't expose any macros from the library. On Sun, Nov 24, 2019 at 9:55 AM Hans Dembinski <hans.dembinski(a)gmail.com> wrote: > > > On 23. Nov 2019, at 04:31, Krzysztof Jusiak via Boost < > boost(a)lists.boost.org> wrote: > > > However, with [Boost].UT there is nothing stopping anyone from using > simple > > macros (one-lines) to achieve other frameworks syntax > > The good bit about it is that it's an opt-in 'feature' as opposed to > being > > the only available option (see example below [1]). > > But then you have split in the user base, some will use the macros others > will use the macro-free syntax, and both will have difficulty in > understanding the code of other. > >

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Re: [Boost-users] [boost] Interest in a C++20 Unit Testing Framework?
by Vinnie Falco 24 Nov '19

24 Nov '19

On Sun, Nov 24, 2019 at 9:49 AM Hans Dembinski via Boost <boost(a)lists.boost.org> wrote: > both will have difficulty in understanding the code of other. BOOST_TEST(b) What could this possibly mean? /me scratches head Regards

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boost::regex (implementation question)
by John Emmas 23 Nov '19

23 Nov '19

Yesterday I downloaded boost v1.71.0 The file 'regex/v4/cregex.hpp' contains declarations for functions like 'regexecA' and 'regexecW'. There are similar declarations for regfree, regcomp & regerror. But where are the implementations for those functions? Or is my own app expected to provide them? Many thanks, John Emmas

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Re: [Boost-users] [boost] Interest in a C++20 Unit Testing Framework?
by mateusz＠loskot.net 23 Nov '19

23 Nov '19

<quote author='Boost - Users mailing list'> (CC'ed to boost-users) On Fri, 22 Nov 2019 at 21:53, Vinnie Falco via Boost <boost(a)lists.boost.org> wrote: > On Thu, Nov 21, 2019 at 7:24 AM Krzysztof Jusiak via Boost-users > <boost-users(a)lists.boost.org>> > > I was wondering whether there is any interest in exploring > > a C++20 single header/single module, macro-free Unit > > Testing Framework with no dependencies? > > I have no interest in a library that requires C++20, especially > considering that C++20 is not even official yet but also because once > C++20 is released, there will be hardly any users for many years. This > project seems very much like it was written "just because", to use the > latest language features, rather than for pragmatic reasons. I don't > see anything compelling to use it over Boost.LightweightTest for > example. I had a look at the current documentation and examples, and I'm glad to see I'm not the only sceptical about it. My opinion is very similar to what Hans, Raffi and Vinnie explained. Macros in testing and benchmarking frameworks are kosher, in fact, they can be very helpul to organize and structure large amount of tests that in turn makes it easier to search and browse through the code. I can't imagine how any of the modern IDE's will support the string-driven syntax. As a long time maintainer of SOCI library, I'm no stranger to the syntax-first library development [1], still, I find the UT's string-based test cases approach as an interesting curiosity with very little practical value. (It falls into similar drawer as the (over)use of emoji in commit messages on GitHub :)). Boost is known as a C++ guinea pigs playground, so any library can make it in. If it does, I just hope Boost will not allow to adopt the UT as a test framework of choice of any/too many of its libraries. [1] https://www.drdobbs.com/database/a-simple-oracle-call-interface/184405930?p… Best regards, -- Mateusz Loskot, http://mateusz.loskot.net _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org https://lists.boost.org/mailman/listinfo.cgi/boost-users </quote> Quoted from: http://boost.2283326.n4.nabble.com/Interest-in-a-C-20-Unit-Testing-Framewor… _____________________________________ Sent from http://boost.2283326.n4.nabble.com

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[review][fixed_string] FixedString review starts Nov 25
by Joaquin M López Muñoz 21 Nov '19

21 Nov '19

The Boost formal review of Krystian Stasiowski and Vinnie Falco's FixedString library will take place November 25 - December 4, 2019. This is an early call for you to consider participating in the review. Feedback and constructive criciticism from experts and not-so-experts alike is very much welcome. FixedString being a relatively small and straightforward library, you will find it very easy to familiarize yourself with it and contribute back to the community. FixedString provides a dynamically resizable string of characters with compile-time fixed capacity and contiguous embedded storage in which the characters are placed within the string object itself. Its API closely resembles that of std::string. GitHub repository: https://github.com/18/fixed_string Online docs: https://18.github.io/doc/fixed_string If you feel like reviewing FixedString you can start now prepping --though I'd ask you to refrain from submitting actual reviews till Nov 25. Read the docs, download/fork the code, read/run it, maybe try integrating it into some project of yours, ask questions to the authors, preferrably on Boost or Boost Users mailing lists. The FixedString initiative arose from a very lively discussion within the community: https://lists.boost.org/Archives/boost/2019/09/246943.php , so I sincerely hope this review will be a fruitful, crowded one. Don't let me down! Best regards, Joaquín M López Muñoz Review manager for candidate Boost.FixedString

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[release] Boost 1.72.0 Beta 1
by Michael Caisse 21 Nov '19

21 Nov '19

Boost release 1.72.0 beta 1 is now available at: <https://dl.bintray.com/boostorg/beta/1.72.0.beta.1/source/> The SHA256 checksums are as follows: 5a6b5cbd27b8ca0c7741b715e022a3bf05aecbb1e73dc72dd82eef9622374bd5 boost_1_72_0_b1.7z 6c85a7aed198757f5e4be66a971ae90a25c4ce32703fecfb5bb19019bd80947c boost_1_72_0_b1.tar.bz2 be4a3fdaa84d5a8b25863651043308e02645f3fbf772b7623ee6462fb1dbad09 boost_1_72_0_b1.tar.gz 95181a5f3de0078b8fc031f63a4dc8be4d70b7d3d5cde3b266d2cd98bd4b61b0 boost_1_72_0_b1.zip For details of what's in the release, see <https://www.boost.org/users/history/version_1_72_0.html>. Please download the beta, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team

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boost::errinfo_stacktrace?
by Nat Goodspeed 21 Nov '19

21 Nov '19

Since the arrival of Boost.Stacktrace, I've been expecting a conventional boost::errinfo_stacktrace helper to join the suite of other boost::errinfo_mumble helpers. Is there a PR open with that? -- NAT LINDEN | Senior Software Engineer | Real Life: Nat Goodspeed LINDEN LAB | Create Virtual Experiences <https://www.lindenlab.com>

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[multi_index] Indices interface type for overload resolution
by Christophe B 20 Nov '19

20 Nov '19

Hi, I have currently template <typename Key, typename Value> std::vector<Key> keys(const std::map<Key, Value> &m) { ... } I'd like to write an overload that works also with the indices interface of multi_index_container. Suppose I have a multi_index_container with ordered unique indexes tagged "by_id" and "by_name". struct by_id {}; struct by_name {}; using BMI = multi_index::multi_index_container<Value, multi_index::indexed_by< multi_index::ordered_unique<by_id, multi_index::key<&Value::id>>, multi_index::ordered_unique<by_name, multi_index::key<&Value::name>> >>; BMI bmi; auto k = keys(bmi.get<by_name>()); Based on the documentation, I tried template< typename Tag,typename Value,typename IndexSpecifierList,typename Allocator > auto keys(const typename multi_index::index< multi_index::multi_index_container<Value,IndexSpecifierList,Allocator>,Tag>::type& m) { typedef decltype(c.key_extractor()(*c.begin())) key_type; // A better definition would be welcome std::vector<key_type> result; result.reserve(c.size()); for (const auto &elem : c) { result.push_back(c.key_extractor()(elem)); } return result; } But the overload resolution fails. What should be the interface of keys in order to support indices interface of multi_index_container? Thank you, Christophe B

3 2

bracket_and_solve_root "rising" option
by Saurabh T 07 Nov '19

07 Nov '19

Hi, I would like a way to bracket the root without having to compute or specify the "rising" flag to "bracket_and_solve_root". Is there a way to edit the bracketing implementation so the user need not specify that option? Thanks, saurabh

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[preprocessor] increase tuple size
by pavel b 07 Nov '19

07 Nov '19

Hi, preprocessor/config/limits.hpp limits tuple size to 64 elements. Changing the BOOST_PP_LIMIT_TUPLE in this file seems not to have any effect. Is it possible to increase the maximal tuple size? Are there scripts to update dependent macros like BOOST_PP_TUPLE_ELEM_* in preprocessor/tuple/elem.hpp? Thanks in advance

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boost::read_graphml
by scaliwagjones＠yahoo.com 07 Nov '19

07 Nov '19

I understand that compiling is no longer necessary to read graphml files.My program compiles but does not link. It worked before I upgraded boost_1_71_0. Program: #include <iostream> #include <boost/graph/graphml.hpp> #include <boost/graph/adjacency_list.hpp> using namespace std; using namespace boost; typedef adjacency_list < vecS, vecS, bidirectionalS > graph_t; graph_t g; dynamic_properties dpg; int main( ) { read_graphml(cin, g, dpg, 0); } Makefile: read_graphml_test: read_graphml_test.cpp g++ -c -I/usr/local/boost_1_71_0 read_graphml_test.cpp ############ g++ -I/usr/local/boost_1_71_0 -L/usr/local/boost_1_71_0/stage/lib read_graphml_test.o Error message: undefined reference to `boost::read_graphml(std::istream&, boost::mutate_graph&, unsigned long)' Thanx

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[filesystem] Management of junction on Windows is broken and api is inconsistent
by Vince R. 06 Nov '19

06 Nov '19

Hello, I am bit disappointed to see that symlink and junctions are still not really properly handled on Windows with boost (and even with standard MS libs but that's another story.) First my environment: Windows 10, VS2019 16.3.7, boost 1.71 (static, x64). I would like to write a small c++ utility that does not use os dependent code to handle files so filesystem seems a good candidate. Here is what I am doing on Windows: cd "C:\Users\Vincent\AppData\Roaming\Apple Computer\MobileSync" mklink /j Backup E:\Backup So basically I am creating inside C:\..\MobileSync a junction folder that points to my second harddisk E:\Backup Then I am checking that Windows recognize it by entering dir command: 01/11/2019 23:48 <DIR> . 01/11/2019 23:48 <DIR> .. 01/11/2019 23:29 <JUNCTION> Backup [E:\Backup] 0 fichier(s) 0 octets 3 Rép(s) 59 393 630 208 octets libres As you can see I have a junction targeting E:\Backup, so now let's see what happens with boost: fs::path p(_T("C:\\Users\\Vincent\\AppData\\Roaming\\Apple Computer\\MobileSync\\Backup")); sys::error_code ec; if (fs::is_symlink(p)) { fs::path pathTarget = fs::read_symlink(p, ec); } When I display the content of pathTarget I have: L"\\Backup" ie Backup if I decode it into human string I might not understand anything about junction but is it not supposed to return E:\Backup ?? When I look at source code I can see the following lines: /********************** boost_1_71_0\libs\filesystem\src\operations.cpp **************************************/ symlink_path.assign( static_cast<wchar_t*>(info.rdb.SymbolicLinkReparseBuffer.PathBuffer) + info.rdb.SymbolicLinkReparseBuffer.PrintNameOffset/sizeof(wchar_t), static_cast<wchar_t*>(info.rdb.SymbolicLinkReparseBuffer.PathBuffer) + info.rdb.SymbolicLinkReparseBuffer.PrintNameOffset/sizeof(wchar_t) + info.rdb.SymbolicLinkReparseBuffer.PrintNameLength/sizeof(wchar_t)); This is wrong since we need to distinguish between a symlink and a junction folder so here is my contribution : --- a/src/operations.cpp +++ b/src/operations.cpp @@ -201,6 +201,12 @@ typedef struct _REPARSE_DATA_BUFFER { # ifndef IO_REPARSE_TAG_SYMLINK # define IO_REPARSE_TAG_SYMLINK (0xA000000CL) # endif +# ifndef IO_REPARSE_TAG_MOUNT_POINT +# define IO_REPARSE_TAG_MOUNT_POINT (0xA0000003L) +# endif +# ifndef IO_REPARSE_TAG_DEDUP +# define IO_REPARSE_TAG_DEDUP (0x80000013L) +# endif inline std::wstring wgetenv(const wchar_t* name) { @@ -1661,12 +1667,24 @@ namespace detail if (!error(::DeviceIoControl(h.handle, FSCTL_GET_REPARSE_POINT, 0, 0, info.buf, sizeof(info), &sz, 0) == 0 ? BOOST_ERRNO : 0, p, ec, "boost::filesystem::read_symlink" )) + if (info.rdb.ReparseTag == IO_REPARSE_TAG_SYMLINK) + { symlink_path.assign( static_cast<wchar_t*>(info.rdb.SymbolicLinkReparseBuffer.PathBuffer) + info.rdb.SymbolicLinkReparseBuffer.PrintNameOffset/sizeof(wchar_t), static_cast<wchar_t*>(info.rdb.SymbolicLinkReparseBuffer.PathBuffer) + info.rdb.SymbolicLinkReparseBuffer.PrintNameOffset/sizeof(wchar_t) + info.rdb.SymbolicLinkReparseBuffer.PrintNameLength/sizeof(wchar_t)); + } + else if (info.rdb.ReparseTag == IO_REPARSE_TAG_MOUNT_POINT) + { + symlink_path.assign( + static_cast<wchar_t*>(info.rdb.MountPointReparseBuffer.PathBuffer) + + info.rdb.MountPointReparseBuffer.PrintNameOffset / sizeof(wchar_t), + static_cast<wchar_t*>(info.rdb.MountPointReparseBuffer.PathBuffer) + + info.rdb.MountPointReparseBuffer.PrintNameOffset / sizeof(wchar_t) + + info.rdb.MountPointReparseBuffer.PrintNameLength / sizeof(wchar_t)); + } # endif return symlink_path; } I will add more suggestions in a next message because there is no consistency between boost and MSVC approach. I don't know the last c++ specifications but it shouldn't be difficult to have a simple approach;

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How multiprecision optimizes allocation?
by Andy 05 Nov '19

05 Nov '19

I have tested boost::mulitprecision::cpp_int and have tested simplest algorithm for int multiplication My test method is several times slower than boost multiplication because I resized product vector to size fist + size second. This allocation take most time, if I use static array on stack, it will be fast for small numbers. What is the riddle of fast comnputing z = x*y in loop for quite small x and y in Boost cpp_int?

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Comparing boost::multiprecision cpp_int and mpz_int
by Andy 05 Nov '19

05 Nov '19

cpp_int is more convenient but mpz_int is faster especially for long numbers? What say benchmarks? For mpz_int I must install GMP on Linux or build MPIR on WIndows (build lib_mpir_core2) ? I want make sample benchmark test but I can't convert cpp_it to mpz_int nor iport bits, whereas for cpp_int I can import_bits(x, xBytes.begin(), xBytes.end()) where vector<uint8_t> xBytes; Question: is possible import byte array to mpz_int?

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Interest in a Unicode library for Boost?
by Zach Laine 04 Nov '19

04 Nov '19

About 14 months ago I posted the same thing. There was significant work that needed to be done to Boost.Text (the proposed library), and I was a bit burned out. Now I've managed to make the necessary changes, and I feel the library is ready for review, if there is interest. This library, in part, is something I want to standardize. It started as a better string library for namespace "std2", with minimal Unicode support. Though "std2" will almost certainly never happen now, those string types are still in there, and the library has grown to also include all the Unicode features most users will ever need. Github: https://github.com/tzlaine/text Online docs: https://tzlaine.github.io/text If you care about portable Unicode support, or even addressing the embarrassment of being the only major production language with next to no Unicode support, please have a look and provide feedback. I gave a talk about this at C++Now in May 2018, and now it's a bit out of date, as the library was not then finished. It's three hours, so, y'know, maybe skip it. For completeness' sake: https://www.youtube.com/watch?v=944GjKxwMBo&index=7&list=PL_AKIMJc4roVSbTTf… https://www.youtube.com/watch?v=GJ2xMAqCZL8&list=PL_AKIMJc4roVSbTTfHReQTl1d… Zach

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Re: [Boost-users] Interest in a Unicode library for Boost?
by Zach Laine 02 Nov '19

02 Nov '19

On Fri, Nov 1, 2019 at 3:41 PM Mathias Gaunard <mathias.gaunard(a)ens-lyon.org> wrote: > This email appears to only be addressed to me and not the list, is > that intentional? > I typed this on my phone so maybe things didn't work exactly as I intended. > It was not intentional. > On Fri, 1 Nov 2019 at 16:09, Zach Laine <whatwasthataddress(a)gmail.com> > wrote: > > > Right. Unicode encodes all natural languages that anyone has taken the > time to put into Unicode. I stand by the implication that natural > languages are crazy. > > Natural languages -- and their transliteration to bytes -- are > arbitrary conventions yes, but they're sufficiently consistent to be > used by millions of people in their personal and professional life > everyday. > There are rules, and however alien they might look to someone who only > needs the fairly straightforward ASCII system, they are not crazy, and > have their own reasons. > > > > So then maybe don't use those parts? They're independent; you don't > have to use them to use the Unicode algorithms. > > Separation of concerns, they do appear coupled in the documentation. > That could just be due to the way the documentation is written. > Could be ... could you point to something in the docs that left you with that impression? I explicitly divided up the documentation along the lines of the separation of concerns found in the code -- the string layer, the Unicode layer, and the text layer. I also tried to be explicit that the first is without dependencies, the second does not depend on the first or the third, and that the third depends on the second. > > Clearly you are more capable than I am. It took me a lot longer to do > than 2 months. Why did you never submit this for a Boost review? You were > thinking about it, ~10 years ago, but you never did.... > > The use case for Unicode is quite niche, and I wasn't particularly > interested in working in that niche further. > Any serious natural language processing engine would probably bypass > Unicode and come up with its own heuristics to parse text, and > applications like GUI toolkits or text editors are specialized enough > that they'd probably never use a library which wasn't specifically > designed for their use case in mind. > That leaves everyday programming, which very rarely needs to do > anything with text beyond treating it as a byte stream, and I believe > wanting to impose the heavyweight Unicode machinery systematically > everywhere is a mistake. > > Anyway, I was just mentioning this because there is prior work > (Boost.Unicode) that you apparently never looked at. > Of course being developed for only a short period of time it doesn't > have the same level of polish as your library. > Ok. FWIW, I did know about your library -- I was there for the BoostCon presentation -- and I was looking forward to using it. Ten years later, I did not look at it again, simply because it had been ten years. > >> and that the database itself is not even accessible, > > > > > > That's also intentional. Another goal of the library is to make Unicode > as simple as possible for naive users who just want to do the basics. If I > find requests for any new feature that has a compelling use case, I'll add > that. > > Being able to replace things like std::isalpha etc. is pretty basic I'd > say. > Having an API that tells you a number of properties about a code point > is one of the most useful parts of Unicode. > I agree I the abstract, but I think that there is a real problem that the properties for a given code point are not necessarily consistent across the various Unicode algorithms. For example, there are multiple notions of "number" that are treated differently in the bidirectional algorithm. Moreover, I don't know of a great use case for a boost::text::is_alpha(). Specifically, it seams that if you are looking for alphabetical characters, you are usually doing something like word-breaking, for which there is already an algorithm, doing a regex match, for which is_alpha() is insufficient, etc. I'm open to hearing about such use cases, of course. > > I don't consider 1.5MB for a database containing all human languages in > widespread use on computers to be a ridiculous size, but YMMV. > > I suppose that's reasonable. > I think the Boost.Unicode one was only 500k but that's an old Unicode > version, and I'm not sure it ever had full collation support. > > > > >> > >> It also doesn't provide the ability to do fast substring search, which > >> you'd typically do by searching for a substring at the character > >> encoding level and then eliminating matches that do not fall on a > >> satisfying boundary, instead suggesting to do the search at the > >> grapheme level which is much slower, and the facility to test for > >> boundary isn't provided anyway. > > > > > > I honestly don't know what you mean here. > > I'm not sure how to clarify this better, but I'll try. > > To search for the utf-8 substring "foo" in the utf-8 string "I really > like foo dogs", there is no need to iterate the string per code point > or per grapheme as you do in your examples. You can just perform the > search at the code unit level, then check that the position before and > after the match does not lie inside a grapheme cluster, i.e. they are > on a valid boundary. > What you need to be able to do that is a function that tells you > whether an arbitrary position in your sequence of utf-8 code units > lies at a grapheme cluster boundary or not (which would probably be a > composition of two separate functions, one that test whether the code > unit is on a code point boundary, and one that tests whether the code > point is on a grapheme cluster boundary). This functionality is not > provided. > > This sort of thing is briefly touched upon in Unicode TR#29 6.4. > I see. This seems like it might be really useful to add. I'll open a ticket for it on Github. Zach

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Re: [Boost-users] Interest in a Unicode library for Boost?
by Zach Laine 01 Nov '19

01 Nov '19

Mathias pointed out that I sent this just to him. So I'm replying again to get this onto the list. Sorry for the noise. On Fri, Nov 1, 2019 at 11:09 AM Zach Laine <whatwasthataddress(a)gmail.com> wrote: > On Fri, Nov 1, 2019 at 6:35 AM Mathias Gaunard < > mathias.gaunard(a)ens-lyon.org> wrote: > >> On Sat, 26 Oct 2019 at 02:11, Zach Laine via Boost-users >> <boost-users(a)lists.boost.org> wrote: >> > >> > About 14 months ago I posted the same thing. There was significant >> work that needed to be done to Boost.Text (the proposed library), and I was >> a bit burned out. >> > >> > Now I've managed to make the necessary changes, and I feel the library >> is ready for review, if there is interest. >> > >> > This library, in part, is something I want to standardize. >> > >> > It started as a better string library for namespace "std2", with >> minimal Unicode support. Though "std2" will almost certainly never happen >> now, those string types are still in there, and the library has grown to >> also include all the Unicode features most users will ever need. >> > >> > Github: https://github.com/tzlaine/text >> > Online docs: https://tzlaine.github.io/text >> >> I would start by removing the superlative statements about Unicode >> being "hard" or "crazy". >> It's not that complicated compared to the actual hard problems that >> software engineers solve everyday. The only thing is that people >> misunderstand what the scope of Unicode is, it's not just an encoding, >> it's a a database and a set of algorithms (relying on said database) >> to facilitate natural text processing of arbitrary scripts, and does >> compromises to integrate with existing industry practices prior to all >> those scripts being brought together under the same umbrella. >> > > Right. Unicode encodes all natural languages that anyone has taken the > time to put into Unicode. I stand by the implication that natural > languages are crazy. > > >> Now the string/container/memory management, this is quite irrelevant. >> That sort of stuff has nothing to do with Unicode and I certainly do >> not want some Unicode library to mess with the way I am organizing how >> my data is stored in memory. >> Your rope etc. containers belong in a completely independent library. >> > > So then maybe don't use those parts? They're independent; you don't have > to use them to use the Unicode algorithms. > > >> What's important is providing an efficient Unicode character database, >> and implementing the algorithms in a way that is generic, working for >> arbitrary ranges and being able to be lazily evaluated (i.e. range >> adaptors). >> I already did all that work more than 10 years ago as a two-month GSoC >> project, though there are some limitations since at that time ranges >> and ranges adaptors were still fairly new ideas for C++. It does >> however provide a generic framework to define arbitrary algorithms >> that can be evaluated either lazily or eagerly. >> > > Clearly you are more capable than I am. It took me a lot longer to do > than 2 months. Why did you never submit this for a Boost review? You were > thinking about it, ~10 years ago, but you never did.... > > >> To be honest I can't say I find your library to be much of an >> improvement, at least in terms of usability, since the programming >> interface seems more constrained (why don't things work with arbitrary >> ranges rather than this "text" containers) > > > They do, of course. I'm not sure why it is you think otherwise. > > >> and verbose (just look at >> the code to do transcoding with iterators), > > > Are you referring to the verbosity of: > > char const * some_utf8 = /* ... */ ; > out = std::ranges::copy(boost::text::as_utf32(some_utf8), out); > > , or: > > out = boost::text::transcode_utf_8_to_32(utf8_first, utf8_last, out); > > , or something else? > > >> the set of features is >> quite small, > > > That is quite intentional. I want to standardize *basic* Unicode > support. I feel that what I have in Boost.Text is the basic set that users > will need, just to support languages or formatting conventions that are not > common in their favorite environment. For instance, today there is no > standard way of taking UTF-8 and turning it into UTF-16, or vice versa; > this library is intended to work at that level. That is, it is intended to > fill in needless gaps in Unicode support that exist in C++ -- gaps that no > other major language besides C has. It is specifically not intended to > replace all ICU functionality. Do you have specific things in mind that > you think ~90% of Unicode-aware C++ users will need? Note that I did not > say 100%. > > >> and that the database itself is not even accessible, > > > That's also intentional. Another goal of the library is to make Unicode > as simple as possible for naive users who just want to do the basics. If I > find requests for any new feature that has a compelling use case, I'll add > that. > > >> and >> last I remember your implementation was ridiculously bloated in size. >> > > I don't consider 1.5MB for a database containing all human languages in > widespread use on computers to be a ridiculous size, but YMMV. > > >> It also doesn't provide the ability to do fast substring search, which >> you'd typically do by searching for a substring at the character >> encoding level and then eliminating matches that do not fall on a >> satisfying boundary, instead suggesting to do the search at the >> grapheme level which is much slower, and the facility to test for >> boundary isn't provided anyway. >> > > I honestly don't know what you mean here. If you use the text::text or > text::string types, those are just contiguous sequences of bits, like a > std::vector or std::string. text::text exposes iterators to those bits > which can be used to get grapheme, code point, and/or UTF-8 byte views of > the underlying data. If you are using something else besides text::text or > text::string two types, you presumably have access to your own bits in your > own representation. What prevents you from doing whatever substring search > you like, via std::search(), std::ranges::includes(), or something else? > Boost.Text is not intended as a string algorithms library. > > I'm pretty sure I made similar comments in the past, but I don't feel >> like any of them has been addressed. >> > > I think you're referring to this email you sent in the Boost.Text > interest thread from 14 months ago: > > """ > The Unicode library I did as a SoC project in 2009 was significantly > smaller than that and if I recall correctly it has more data than the one > in your library. > Clearly some work can be done here to better optimize the database size. > """ > > I did make it a bit smaller. The other comments are new. > > Zach > >

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Serialization of an instance of a Derived Template Class
by Pritam Gharat 01 Nov '19

01 Nov '19

Hi, I am using Boost to serialize pointers of a base class which points to instances of a derived template class. I am using boost 1.7.0 and running it on Ubuntu 16.04. The source code of the example is available at https://github.com/PritamMG/Boost-Serialization-Example My example has a base class Bar_A (definition available in include/Abstract.hpp) which has a virtual function toStr(). It has two derived classes Bar_B and Bar_C. Bar_B is a template class. I have registered the derived classes in sc/Test.cpp. Class ObjectNew (include/Object.hpp) has a member pointer of type Bar_A which points to instances of classes Bar_B and Bar_C. I get an error as "unregistered class". I am not sure for which class do I get this error message. There is also an issue of non-default. If Bar_B does not have a default constructor, save_construct_data and load_construct_data are over-ridden and there I run into an error "too many template-parameter-lists". How do I define these functions? Thanks, Pritam

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