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Re: [Boost-users] [multi_array] Feature request: constructor and resize from values
by DV Henkel-Wallace 30 Nov '20

30 Nov '20

If an object does not have a default constructor what could it mean to have a block of memory holding one that has not been initialized? How would your program know if the object had been properly initialized or not? There are three ways to address this: 1 - A pointer, as already mentioned. A null pointer means the spot does not refer to ("contain") a valid object -- or any object at all. 2 - use a variant 3 - create a default constructor (which you could do by changing the signature of your constructor to something like (int = 0) or (int = -1) assuming those values are invalid). In all cases, regardless of semantics or implementation you'll either have to check at runtime for a valid object OR, if you know for other reasons which locations are valid, use the default constructor with any value you'd like. If you don't want to use pointers there are a couple of other possibilities: > > Date: Sun, 22 Nov 2020 12:06:04 +0100 > From: Eugenio Bargiacchi <svalorzen(a)gmail.com <mailto:svalorzen@gmail.com>> > > Ah, sorry, I thought it would have been automatically clear. Consider this > example: > > class A { > public: > A(int) {} > }; > > boost::multi_array<A,2> array(boost::extents[2][2]); // Compiler error > boost::multi_array<A,2> array(boost::extents[2][2], A(3)); // What I would > like > > array.resize(boost::extents[2][2]); // Again, compiler error > array.resize(boost::extents[2][2], A(2)); // What I would like > > The variable `array` cannot be constructed in any way, as multi_array will > try to default-construct it, and that will fail. Trying to simply create > `array` with its default constructor works (although it will obviously be a > zero-sized array), but when trying to resize it (to actually store things), > the same thing will happen.

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[multi_array] Feature request: constructor and resize from values
by Eugenio Bargiacchi 22 Nov '20

22 Nov '20

I'd love to be able to use multi_array with classes that do not have a default constructor. At the moment, this is impossible, as both the constructor and resize functions only take extents as arguments (and possibly some other options), but no value_type, as for example std::vector does. Thus, trying to store objects without a default constructor in a multi_array results in hard compiler errors, with no workaround that I know of. This happens to me fairly often, as I use multi_array to organize sets of complex objects. If there is a technical reason why this is not possible, I would also be happy to learn it. Best regards, Eugenio Bargiacchi

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[xpressive] I got a crash in after i upgrade from 1.44 to 1.74
by forston_shi＠trendmicro.com 20 Nov '20

20 Nov '20

Hi Boost Users I met a crash in following code after I upgrade from 1.44 to 1.74, When I used "-O1 -DNDEBUG" to compile, it will crash. But when I used "-O1" or "-DNDEBUG" or "-O0 -DNDEBUG", it will not crash. In 1.44, all of them are ok. My GCC version is 4.1.2 and test in redhat-AS 4 32 bit. callstack #0 at ./boost_1_74_0_bk/boost/xpressive/detail/static/transmogrify.hpp:160 160 char const *name_end = m.name_ + std::strlen(m.name_); #1 at ./boost_1_74_0_bk/boost/proto/transform/detail/preprocessed/fold_impl.hpp:80 #2 at ./boost_1_74_0_bk/boost/proto/transform/detail/preprocessed/fold_impl.hpp:80 #3 at ./boost_1_74_0_bk/boost/xpressive/detail/static/compile.hpp:79 #4 at ./boost_1_74_0_bk/boost/xpressive/detail/static/compile.hpp:99 #5 0x08049d5f in main () at ./boost_1_74_0_bk/boost/xpressive/basic_regex.hpp:252 Can you help to check this problem? Best regards Forston callstack Following is source code. #include <boost/xpressive/basic_regex.hpp> #include <boost/xpressive/regex_primitives.hpp> #include <boost/xpressive/match_results.hpp> #include <boost/xpressive/regex_algorithms.hpp> int main(int argc, char* argv[]) { std::wstring uri_string = L"https://192.168.1.1/test"; printf("begin regex_match %ls \n ", uri_string.c_str()); using namespace boost::xpressive; static wsregex const uri_regex = bos >> (s1 = (alpha >> *(alnum | L'+' | L'-' | L'.'))) >> L"://" >> (s2 = *(alnum | L'-' | L'.' | L':' | L'@' | L'[' | L']' | L'_')) >> !(as_xpr(L'/') >> (s3 = (*_))) >> eos ; wsmatch result; try { if (!regex_match(uri_string, result, uri_regex)) { printf( "regex_match failed %ls \n ", uri_string.c_str()); return -1; } } catch (std::exception& e) { printf("regex_match failed %ls \n ", uri_string.c_str()); return -1; } printf("end regex_match success %ls \n ", uri_string.c_str()); return 0; } TREND MICRO EMAIL NOTICE The information contained in this email and any attachments is confidential and may be subject to copyright or other intellectual property protection. If you are not the intended recipient, you are not authorized to use or disclose this information, and we request that you notify us by reply mail or telephone and delete the original message from your mail system. For details about what personal information we collect and why, please see our Privacy Notice on our website at: Read privacy policy<http://www.trendmicro.com/privacy>

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[asio] Prevent socket inheritance on Windows
by Klebsch, Mario 17 Nov '20

17 Nov '20

Hello everybody, I am using boost as communication framework in a library for Windows. I am getting problems, when the client code, that uses our library, creates windows processes and inherits handles, e.g. by using popen(). I currently observing two problems. 1. Even though my library has closed the socket, the peer keeps an active connection. 2. When there is a pending async read operation, calling close() does not lead to the read handler being invoked with an error. My library closes a socket in its shutdown process and because it also terminates the io_service during shutdown, it waits for the termination of the pending read operation. The second problem is the one, that is visible to the client, since our library hands during shutdown. Unfortunately it is not triggered by just inheriting a socket handle to a child process. I know, the socket handle gets inherited to the child process and when I kill the child process, the pending async operation terminates. I also have seen the pending read operation to terminate, then the peer system sends some data. The data seems to be read fine, although the socket has already been closed by our library. The io_service is blocked in the call to GetQueuedCompletionStatus() on its io completion port. It seems, the io completion port still is linked the the socket, although the socket has been closed. The problem is triggered reliably, when using my fully integrated library, but I have not yet managed to write a small simple sand alone program to demonstrate this problem. * Does anybody on this mailing list has a clue, what may cause the 2nd problem, where the async operation does not terminate upon closing the socket. * Does anybody know of a reliable way to prevent an asio socket from being inherited. I found some web pages mentioning WSA_FLAG_NO_HANDLE_INHERIT, but have not found a way to get boots to use this flag other than patching my boost source code. Thanks to everybody, Mario -- Mario Klebsch Actia I+ME GmbH Mario.klebsch(a)ime-actia.de<mailto:Mario.klebsch@ime-actia.de> Dresdenstrasse 17/18 Fon: +49 531 38 701 716 38124 Braunschweig Fax: +49 531 38 701 88 Germany

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[release] Boost 1.74.0 beta 1 released
by Marshall Clow 14 Nov '20

14 Nov '20

Boost release 1.75.0 beta 1 is now available at: <https://dl.bintray.com/boostorg/beta/1.75.0.beta1/source/> The SHA256 checksums are as follows: 3f01d3e5dc822e151892040d4667e364ea808d208d2e49cc7a1802bd4da3d4cc boost_1_75_0_b1.7z 9b75a80f845d4ae312e3c9151ffdfe3fed450973095e0a15c68d0be394f2f2df boost_1_75_0_b1.tar.bz2 123519d4b056fbbd69e452db880abe2c7e55f21779d44a4d6b6c714d5c13c3ee boost_1_75_0_b1.tar.gz b73e01d22d5b3d2ff82f14a371e3974fab30448bf6ff5ac8b9c829539a19c2d7 boost_1_75_0_b1.zip For details of what's in the release, see <https://www.boost.org/users/history/version_1_75_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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[release] Boost 1.75.0 Beta 1 Release Candidate 2
by Marshall Clow 13 Nov '20

13 Nov '20

The second release candidates for the 1.75.0 beta release are now available at: <https://dl.bintray.com/boostorg/beta/1.75.0.beta1/source/> The SHA256 checksums are as follows: 3f01d3e5dc822e151892040d4667e364ea808d208d2e49cc7a1802bd4da3d4cc boost_1_75_0_b1_rc2.7z 9b75a80f845d4ae312e3c9151ffdfe3fed450973095e0a15c68d0be394f2f2df boost_1_75_0_b1_rc2.tar.bz2 123519d4b056fbbd69e452db880abe2c7e55f21779d44a4d6b6c714d5c13c3ee boost_1_75_0_b1_rc2.tar.gz b73e01d22d5b3d2ff82f14a371e3974fab30448bf6ff5ac8b9c829539a19c2d7 boost_1_75_0_b1_rc2.zip As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. -- The Release managers

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Compile issues when cross compiling for iOS with external dependencies
by Ardavon Falls 10 Nov '20

10 Nov '20

When attempting to cross-compile boost 1.69.0 for iOS (with clang) and using external dependencies it fails to compile because when it tests to see if the dependencies are valid, it fails to compile the test program correctly due to it attempting to add incorrect linker flags. I tried modifying the boost.build to not add those flags but it seemed to unravel a rat's nest of issues (attempting to link with librt even though its for iOS, compiled the test program for x86 and not arm, etc.., etc..) The error I keep getting is... ld: unknown option: --start-group Thank you for your help. I am using the following b2 options.. ./b2 --prefix=/Users/afalls/delete-me/build-boost/install/ \ --build-dir=/Users/afalls/delete-me/build-boost/build/ \ --user-config=/Users/afalls/delete-me/build-boost/ios-config.jam \ --with-math \ --with-wave \ --with-container \ --with-contract \ --with-exception \ --with-graph \ --with-iostreams \ --with-locale \ --with-log \ --with-program_options \ --with-random \ --with-regex \ --with-mpi \ --with-serialization \ --with-coroutine \ --with-fiber \ --with-context \ --with-timer \ --with-thread \ --with-chrono \ --with-date_time \ --with-atomic \ --with-filesystem \ --with-system \ --with-graph_parallel \ --with-stacktrace \ --with-test \ --with-type_erasure \ -q \ -j 16 \ toolset=clang \ threading=multi \ architecture=arm \ abi=aapcs \ binary-format=mach-o \ address-model=64 \ cxxflags="${IOS_CXXFLAGS}" \ cflags="${IOS_CFLAGS}" \ target-os=iphone \ link=static \ variant=release \ define=_LITTLE_ENDIAN \ install My user-config.jam file is below... import os ; using clang : : /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -arch arm64 -DBOOST_AC_USE_PTHREADS -DBOOST_SP_USE_PTHREADS -Wno-unused-local-typedef -Wno-nullability-completeness -miphoneos-version-min=9.0 -fPIC : <stripper> <root>/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk <architecture>arm <target-os>iphone <include>/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk/usr/include ; using zlib : 1.2.11 : <include>/Users/afalls/.conan/data/zlib/1.2.11/channel/niantic/package/d522642044ded35b1d89ab2201a41e2c5d74a0b0/include <search>/Users/afalls/.conan/data/zlib/1.2.11/channel/niantic/package/d522642044ded35b1d89ab2201a41e2c5d74a0b0/lib <name>z ; using lzma : 5.2.4 : <include>/Users/afalls/.conan/data/xz_utils/5.2.4/channel/niantic/package/d522642044ded35b1d89ab2201a41e2c5d74a0b0/include <search>/Users/afalls/.conan/data/xz_utils/5.2.4/channel/niantic/package/d522642044ded35b1d89ab2201a41e2c5d74a0b0/lib <name>lzma ; using bzip2 : 1.0.8 : <include>/Users/afalls/.conan/data/bzip2/1.0.8/channel/niantic/package/d522642044ded35b1d89ab2201a41e2c5d74a0b0/include <search>/Users/afalls/.conan/data/bzip2/1.0.8/channel/niantic/package/d522642044ded35b1d89ab2201a41e2c5d74a0b0/lib <name>bz2 ; using zstd : 1.4.4 : <include>/Users/afalls/.conan/data/zstd/1.4.4/channel/niantic/package/d522642044ded35b1d89ab2201a41e2c5d74a0b0/include <search>/Users/afalls/.conan/data/zstd/1.4.4/channel/niantic/package/d522642044ded35b1d89ab2201a41e2c5d74a0b0/lib <name>zstd ;

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Boost version not matching according to the manual
by Arnab Chaudhuri 08 Nov '20

08 Nov '20

To whom it may concern, I have installed boost and to the version is 1.65.1.0ubuntu1 . It is written while installing that the minimum requirement is 1.66. Can you please tell me how to update my version. The commands I used to install boost are as follows: *sudo apt install libboost-dev**sudo apt install libboost-all-dev* *Thanking you,* *Arnab Chaudhuri.*

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Validating downloads on Windows
by Kenneth Porter 08 Nov '20

08 Nov '20

I thought I had a corrupted download and wanted to relate my experience on how to validate the zip file downloads on Windows. The Boost archives (tar, zip, etc.) all have a matching small .json file that contains a SHA256 hash of the archive file. Under Windows 10, you can use certutil.exe from a command line to compute the hash for the archive and compare it to the value in the .json file: C:\Users\ken\Downloads>certutil -hashfile boost_1_75_0_b1_rc1.zip SHA256 SHA256 hash of boost_1_75_0_b1_rc1.zip: 07ddca7c39ea9152bad73bee4f10f2c9c8e3a2d7e153aa945a343f83eca5db59 CertUtil: -hashfile command completed successfully. (I thought my download was corrupted because I was using an ancient version (5.50) of InfoZip's unzip program and it was reporting errors. I updated to version 6 and it unpacked the same file just fine.)

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[release] Boost 1.75.0 Beta 1 Release Candidate 1
by Marshall Clow 07 Nov '20

07 Nov '20

The first release candidates for the 1.75.0 beta release are now available at: <https://dl.bintray.com/boostorg/release/1.75.0.beta1/source/> The SHA256 checksums are as follows: c271f488c7c8de7c147bf8675d578fb2f06c6c171d9547c5a40cddccb9f2a6c4 boost_1_75_0_b1_rc1.7z 0db0944e9d2250907e011900eea304ca055d1c418d38b3fbb1eee692a6b851a6 boost_1_75_0_b1_rc1.tar.bz2 624bd6b03d86bf1387b4e8927dab16b4198f255f15dd71d6a8c1c5ec270584b3 boost_1_75_0_b1_rc1.tar.gz 07ddca7c39ea9152bad73bee4f10f2c9c8e3a2d7e153aa945a343f83eca5db59 boost_1_75_0_b1_rc1.zip As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. -- The Release managers

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Why did ip::basic_resolver::query get depreciated in 1.66?
by Luke Knoble 06 Nov '20

06 Nov '20

I ask because I replaced its return value with an endpoint in a tcp resolver function and my dns resolution started working..! Cheers, Luke Knoble

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Boost 1.74: Coroutines2 on MSVC 2019 / C++20
by Daniel Petrovic 29 Oct '20

29 Oct '20

Using Boost 1.74. By using coroutines 2 on MSVC 2019 (v16.7.7) with C++20 there is a compilation issue regarding result_of which is replaced by invoke_result in C++20. Is there already some patch for 1.74 or maybe work in progress for 1.75 regarding this issue ? Regards Daniel

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[Signals2] Deprecated header warning VS2017 Boost 1.74
by Peter Barker 27 Oct '20

27 Oct '20

Hi, Just upgraded to Boost 1.74 from Boost 1.71. I'm getting a warning: c:\releases\lib\boost\boost_1_74_0\include\boost\function_output_iterator.hpp(14): note: This header is deprecated. Use <boost/iterator/function_output_iterator.hpp> instead. from this MWE: #include <boost/signals2/signal.hpp> int main() { } I'll have to #define BOOST_ALLOW_DEPRECATED_HEADERS I guess, but I'm surprised Boost libraries are using deprecated Boost headers. Regards, Pete

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A Newbie Boost.Build with Variants Question
by Ryan Heniser 24 Oct '20

24 Oct '20

Hi, I am building Boost 1.61 (we need this old version for other libraries) for the first time at work with Boost.Build (b2). I have successfully built Boost (using b2) for gcc 4.8. If I want to add one or more variants (for example using gcc 6.3), where should I put the Boost header’s include directory? Should one go inside each variant or should just one go at the root directory containing the variant directories? Kind regards, Ryan

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[Newbie][Intrusive] - Beginners question
by Gaier, Bjoern 22 Oct '20

22 Oct '20

Hey everybody, I looked into the boost intrusive container and played around with it a bit. I tried the following code: struct animal : public boost::intrusive::list_base_hook<> { std::string name; int legs; animal(std::string n, int l) : name{std::move(n)}, legs{l} {} }; int main(int argc, char **argv) { std::vector<animal> test; boost::intrusive::list<animal> wuff; for(int n = 0; n < 5; n++) { test.push_back(animal("Katze", 4)); } for(int n = 0; n < 5; n++) { wuff.push_back(test[n]); } for(int n = 0; n < 15; n++) { wuff.push_back(test[n]); } for(auto elem : wuff) { printf("%s\n", elem.name.c_str()); } } This code does crash! I guess this is because "test" relocated the memory and therefor "wuff" lost its references. I would expect the same result if I would have a std::list with pointers to animal structures - this is why I wonder what the benefit of an intrusive container is compared to the same container with just pointers in it. Hope someone can explain me this! Thank you in advance and kind greetings Björn Als GmbH eingetragen im Handelsregister Bad Homburg v.d.H. HRB 9816, USt.ID-Nr. DE 114 165 789 Geschäftsführer: Dr. Hiroshi Nakamura, Dr. Robert Plank, Markus Bode, Heiko Lampert, Takashi Nagano, Junichi Tajika, Ergin Cansiz.

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Does boost promise/future support corroutines?
by David Frank 19 Oct '20

19 Oct '20

Hi, Does boost promise/future support coroutines? For example, the get call only block the running coroutine, instead of the whole thread? Thanks,David

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Boost.MSM: Problem with defered events
by Georg Gast 16 Oct '20

16 Oct '20

Dear Boost users, i am currently writing a driver for the ADS1256 chip with Boost.MSM. Yes, there are other drivers. I do this for training and fun. During the startup phase i need to defer the requests from the user as the SPI bus is not yet available. To model the behaviour the most correct, i tried to model it with MSM. In the transition table, i use the "Defer" action to defer these events. In my Idle state, after the startup phase, there is a transition with this defered event going to the "work" states. In the debugger i can see, that the defered_event_queue holds one defered event and it is of my type but it is not processed. I did use boost 1.67.0 (from debian buster ) and also 1.74.0 (self compiled) to test this. My program can be also compiled under Windows and VS2019 as i handled the hardware interfacing with a abstract class. It works under Windows and 1.74.0. With VS2017 and 1.67.0 it also does not work. Under Linux and gcc it always stops at the Idle state where i wait for the defered event. At the end is my transition table. Any ideas are welcome! Georg // clang-format off struct transition_table : mpl::vector< // +----------------+-------------------+----------------+---------------------------+----------------------+ // Region 0 // +----------------+-------------------+----------------+---------------------------+----------------------+ // Start Event Next Action Guard // +----------------+-------------------+----------------+---------------------------+----------------------+ Row < NotIntialized , ev_Init , WaitDRDYID , none , none >, Row < WaitDRDYID , ev_CheckFlags , ReadID , none , IsDrdy0 >, Row < ReadID , ev_CheckFlags , none , none , none >, Row < ReadID , Spi::Reply , ReadIDFailed , none , IsIDNotOk >, Row < ReadID , Spi::Reply , Idle , none , IsIDOk >, // during the startup phase these event must be defered Row < NotIntialized , ev_MultiStart , none , Defer , none >, Row < WaitDRDYID , ev_MultiStart , none , Defer , none >, Row < ReadID , ev_MultiStart , none , Defer , none >, // +----------------+-------------------+----------------+---------------------------+----------------------+ Row < Idle , ev_CheckFlags , none , none , none >, Row < Idle , ev_MultiStart , MConfigWaitDRDY, none , none >, // +----------------+-------------------+----------------+---------------------------+----------------------+ Row < MConfigWaitDRDY, ev_CheckFlags , MSwitchConfig , none , IsDrdy0 >, Row < MSwitchConfig , ev_CheckFlags , none , none , none >, Row < MSwitchConfig , Spi::Reply , MMuxWaitDRDY , none , IsECNotFailed >, Row < MMuxWaitDRDY , ev_CheckFlags , MSwitchMux , none , IsDrdy0 >, Row < MSwitchMux , ev_CheckFlags , none , none , none >, Row < MSwitchMux , Spi::Reply , MSync , none , IsECNotFailed >, Row < MSync , Spi::Reply , MDataWaitDRDY , none , IsECNotFailed >, Row < MDataWaitDRDY , ev_CheckFlags , MReadData , none , IsDrdy0 >, Row < MReadData , ev_CheckFlags , none , none , none >, Row < MReadData , Spi::Reply , Idle , WorkDone , IsWorkDone >, Row < MReadData , Spi::Reply , MMuxWaitDRDY , RemoveDoneWork , IsStillWorkTodo >, // +----------------+-------------------+----------------+---------------------------+----------------------+ // Region 1 // +----------------+-------------------+----------------+---------------------------+----------------------+ Row < DrdyUndefined , ev_DRDY_0 , Drdy0 , none , none >, Row < DrdyUndefined , ev_DRDY_1 , Drdy1 , none , none >, Row < Drdy0 , ev_DRDY_0 , none , none , none >, Row < Drdy0 , ev_DRDY_1 , Drdy1 , none , none >, Row < Drdy1 , ev_DRDY_0 , Drdy0 , none , none >, Row < Drdy1 , ev_DRDY_1 , none , none , none >, // +----------------+-------------------+----------------+---------------------------+----------------------+ // Region 2 // +----------------+-------------------+----------------+---------------------------+----------------------+ // Start Event Next Action Guard // +----------------+-------------------+----------------+---------------------------+----------------------+ Row < AllOk , Spi::Reply , ErrorMode , none , IsECFailed > // +----------------+-------------------+----------------+---------------------------+----------------------+ > {}; // clang-format on

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[Circular Buffer] Why doesn't have “emplace” interface?
by Марсель Галимуллин 16 Oct '20

16 Oct '20

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Boost configuration for VS Code / MacOS X Catalina
by Stefano Gragnani 12 Oct '20

12 Oct '20

Hi, how should i configure vs code to use Boost? I tried to compile the following example: #include <iostream> #include <boost/multiprecision/float128.hpp> #include <boost/math/special_functions/gamma.hpp> int main() { using namespace boost::multiprecision; // Operations at 128-bit precision and full numeric_limits support: float128 b = 2; // There are 113-bits of precision: std::cout << std::numeric_limits<float128>::digits << std::endl; // Or 34 decimal places: std::cout << std::numeric_limits<float128>::digits10 << std::endl; // We can use any C++ std lib function, lets print all the digits as well: std::cout << std::setprecision(std::numeric_limits<float128>::max_digits10) << log(b) << std::endl; // print log(2) = 0.693147180559945309417232121458176575 // We can also use any function from Boost.Math: std::cout << boost::math::tgamma(b) << std::endl; // And since we have an extended exponent range we can generate some really large // numbers here (4.02387260077093773543702433923004111e+2564): std::cout << boost::math::tgamma(float128(1000)) << std::endl; // // We can declare constants using GCC or Intel's native types, and the Q suffix, // these can be declared constexpr if required: constexpr float128 pi = 3.1415926535897932384626433832795028841971693993751058Q; return 0; } but that's what I get: Executing task: g++-10 -g -std=c++17 '-fext-numeric-literals' main.cpp -L/usr/local/Cellar/gcc/10.2.0/lib/gcc/10/ -lquadmath -o main.out < main.cpp:2:10: fatal error: boost/multiprecision/float128.hpp: No such file or directory 2 | #include <boost/multiprecision/float128.hpp> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ compilation terminated. The terminal process "/bin/zsh '-c', 'g++-10 -g -std=c++17 '-fext-numeric-literals' main.cpp -L/usr/local/Cellar/gcc/10.2.0/lib/gcc/10/ -lquadmath -o main.out'" failed to launch (exit code: 1). My task.json is: { // See https://go.microsoft.com/fwlink/?LinkId=733558 <https://go.microsoft.com/fwlink/?LinkId=733558> // for the documentation about the tasks.json format "version": "2.0.0", "tasks": [ { "label": "Build with g++ 10", "type": "shell", "command": "g++-10", "args": [ "-g", "-std=c++17", "'-fext-numeric-literals'", "main.cpp", "-L/usr/local/Cellar/gcc/10.2.0/lib/gcc/10/", "-lquadmath", "-o", "main.out" ], "group": { "kind": "build", "isDefault": true } }, { "label": "Build with Intel ICC", "type": "shell", "command": "icc", "args": [ "-g", "-std=c++17", "main.cpp", "-o", "main.out" ], "group": { "kind": "build", "isDefault": true } }, { "label": "Run Project", "type": "shell", "command": "./main.out", "group": { "kind": "build", "isDefault": true } } ] } And my c_cpp_properties.json is: { "configurations": [ { "name": "Mac", "includePath": [ "${workspaceFolder}/**", "/usr/local/Cellar/boost/1.73.0/include/**" ], "defines": [], "macFrameworkPath": [], "compilerPath": "/usr/local/bin/g++-10", "cStandard": "gnu18", "cppStandard": "gnu++14", "intelliSenseMode": "gcc-x64" } ], "version": 4 } Thanks Stefano Gragnani

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A question about boost::uuid
by Shishir Pandey 10 Oct '20

10 Oct '20

Hi all, I have been trying to figure out how to use murmurhash3 with boost::uuid. Looking at the documentation it is not entirely clear to me if a class implementing murmurhash3 that provides the interface defined by NameHashProvider would be sufficient. If yes, would creating a wrapper over the following implementation work? https://github.com/aappleby/smhasher/blob/master/src/MurmurHash3.cpp Can anyone direct me to some similar implementation perhaps not of using murmurhash3 but of using any other algorithms? Regards, Shishir Pandey -- Necessity is not an established fact, but an interpretation. - Friedrich Wilhelm Nietzsche

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Re: [Boost-users] [Boost-announce] [PFR][review] Result
by Antony Polukhin 09 Oct '20

09 Oct '20

On Thu, Oct 8, 2020, 13:51 Benedek Thaler via Boost-announce < boost-announce(a)lists.boost.org> wrote: <...> > Benedek > review wizard > Many thanks for beeng the review manager! >

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Re: [Boost-users] [Boost-announce] [FPR] Review of FPR starts Today: Sept 28 - Oct 7
by Nat Goodspeed 05 Oct '20

05 Oct '20

On Mon, Sep 28, 2020 at 1:15 PM Benedek Thaler via Boost-announce < boost-announce(a)lists.boost.org> wrote: - How much effort did you put into your evaluation? A glance? A quick > reading? In-depth study? > I have read only the announcement email, but it prompts a very interesting question: does the FPR library facilitate integration with Boost.Serialization? If not yet, how hard would it be to improve the interoperability of those two libraries? If the FPR documentation already addresses this point, a terse reply to that effect will suffice.

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improve TypeTraits
by Gero Peterhoff 04 Oct '20

04 Oct '20

Hello John, you have probably already read that I think some new TypeTraits are useful. Here are the details: a) very useful: precise type classification - this is the basis of every abstraction and should definitely be implemented - is_character: contains only characters (char32/16/8_t, wchar_t, char); is_un/signed_character - is_integer: contains only integers and no characters and no bool (u/int8..X_t); is_un/signed_integer - is_logic: contains only logical types (bool and boost::tribool, *)) - is_string: contains everything that can be used as a string, but needs these specializations: 1) is_bounded_string (similar to is_bounded_array) 2) is_unbounded_string (similar to is_unbounded_array) 3) is_static_string (for boost::basic_static_string) 4) is_string_ref (for boost::basic_string ref) 5) is_string_view (for std::basic_string_view) 6) is_string_class (for std::basic_string) - character_of: the underlying character type based on is_string b) very useful - remove_cv_ptr (similar to remove_cv_ref) - make_same_signed (similar to make_un/signed): changes the sign depending on a type - conditional_signed: changes the sign depending on a truth value - is_same_signed: same sign c) also makes sense - is_tuple - is_rational (similar to boost::is_complex) - is_binary: if base==2 (numeric_limits::radix==2) - is_decimal: if base==10 (numeric_limits::radix==10) d) - is_native: a type is natively available on the platform (e.g. int64_t: Linux32:false, Linux64:true; float80_t: x86:true, else:false) - is_vectorisable: a type can be vectorized natively on the platform - there are basic SSE/AVX/SVE/... functions However, I have a problem: boost/std::is_integral contain bool. Perhaps you can do that like this, but it leads to problems with is_arithmetic, since is_arithmetic is based on is_integral and thus contains bool. I think the point of is_arithmetic is to be able to calculate numerically with the type - so the scenarios are not useful: abs(bool), sin/cos/...(bool), etc. The same applies to characters. There are two possible solutions: - redefine is_arithmetic -> is_integer || is_floating_point - a new TypeTrait is_numeric (e.g.) -> is_integer || is_floating_point There are some differences between boost- and std-TypeTraits. Can you please include that in the documentation? Furthermore there seem to be errors with char8_t, e.g. boost::is_unsigned<char8_t> -> false, std::is_unsigned<char8_t> -> true (correct). Summary With these measures, a large number of template functions/classes can then be tailored precisely to the application and incorrect use can be prevented. regards Gero *) I've written a couple of classes for logic: bool3_t (a modern variant of boost::tribool), bool4_t (http://www.filosofia.unimi.it/dagostino/wp-content/uploads/2017/05/Belnap.p…) and bool2_t (for completeness)

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Using Boost.Random with fixed-point numbers
by John W 03 Oct '20

03 Oct '20

I have a fixed-point number class (based on libfixmath) which in code largely behaves like a float due to various operator overloading. Now, I am trying to generate random numbers with them. Uniform random is easy enough — just reinterpret some random bits as my fixedpoint type. However, I'd like to have other distributions, like boost::random::normal_distribution. But from what I can tell, Boost.Random might have some baked-in assumptions about only working on float/double/long double. Is that correct? Or are there ways I can more-or-less transparently use boost::random::xxx distributions with my custom type? Basically, I want to know how much the <RealType> template argument can be abused. In std::random, there is some clear language[1], saying: "The result type generated by the generator. The effect is undefined if this is not one of float, double, or long double." and I believe boost::random aims to be in agreement with std::random, generally. But I could not find such clear language in the Boost.Random docs. Thanks -John [1] https://en.cppreference.com/w/cpp/numeric/random/uniform_real_distribution

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[Boost.Compute]: double3 - typedef redefinition with different types
by Manfred Doudar 30 Sep '20

30 Sep '20

Hello List, [Posting over from the Slack channel which didn't get any attention]: Any Boost.Compute users here that might be able to help with the following code snippet - BOOST_COMPUTE_ADAPT_STRUCT(double3, double3, (x, y, z)) BOOST_COMPUTE_FUNCTION(bool, CompareX, (double3 a, double3 b), { return a.x < b.x; }); boost::compute::vector<double> points; ... auto it = boost::compute::min_element(points.begin(), points.end(), CompareX, queue); results in the kernel compilation failure - --- build log --- <kernel>:9:3: error: typedef redefinition with different types ('struct double3' vs 'double __attribute__((ext_vector_type(3)))') } double3; ^ cl_kernel.h:154:1: note: previous definition is here __NV_DECLARE_VECT_TYPES(double, double) ^ cl_kernel.h:114:61: note: expanded from macro '__NV_DECLARE_VECT_TYPES' typedef __attribute__(( ext_vector_type(3) )) CTYPE CLTYPE##3; \ ^ <scratch space>:53:1: note: expanded from here double3 ^ ^@ Thanks, /M

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