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Re: [Boost-users] boost.org domain expired?
by Kenneth Porter 03 May '22

03 May '22

Confirmed. Here's a site snapshot from yesterday in case someone needs it: https://web.archive.org/web/20220502193202/https://www.boost.org/

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boost.org domain expired?
by Warren Weckesser 03 May '22

03 May '22

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[Math / Distributions] How do mean, variance, etc end up in scope?
by Warren Weckesser 02 May '22

02 May '22

This is probably more of a C++ question than a Boost/Math question. I think the answer comes down to a (surprising?) Boost namespace convention. In a program like this: ``` #include <boost/math/distributions/beta.hpp> using boost::math::beta_distribution; int main() { float a = 1.5f; float b = 3.0f; beta_distribution<float> dist(a, b); auto m = mean(dist); } ``` how does the name 'mean' end up in scope in 'main()'? I would have expected (and preferred!) something like 'using boost::math::mean;' to be required. Warren

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[statechart] non-virtual unconsumed_event
by Alexandre Bouchu 26 Apr '22

26 Apr '22

Hello, Looking for guidance regarding best practices using boost statechart. When it came time to have a mechanism to catch unhandled events and pass that information back to clients, my first choice has been to override unconsumed_event public function in state_machine class. Given that the static code analysis tool we run complains about the dangers of overriding a non-virtual function, I came here to get more background into maybe why this function was not made virtual in the first place. Is there for example a better implementation practice that would see this "catch all" function stay empty, as is the case with state_machine implementation, and instead use another technique to provide meaningful feedback to clients when the action or state transition requested is invalid/unsupported? I feel I can justify and waive this code analysis tool warning up the food chain, but yet wanted some feedback from this user group first. Thanks, Alexandre

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constexpre limits
by Gero Peterhoff 21 Apr '22

21 Apr '22

Hello John, i switched std::numeric_limits<float128> completely to constexpr because it bothered me a lot. Especially: - quiet_NaN (removed sqrt) - has/signaling_NaN adjusted Hope that's ok. regards Gero

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Unable to run example code "line_interpolate"
by Ajay Kumar G 19 Apr '22

19 Apr '22

Hello, First of all, thank you for your contributions. Indeed it was a greatly useful library with very detailed documentation. While trying to run a sample example code "line_interpolate" from following link: https://www.boost.org/doc/libs/1_79_0/libs/geometry/doc/html/geometry/refer… There is an error that appears saying " error: ‘line_interpolate’ was not declared in this scope" but i dint understand the reason. While other examples from the reference( https://www.boost.org/doc/libs/1_79_0/libs/geometry/doc/html/geometry/matri…) work fine without any issues. May I know the actual cause of this issue? Working platform: Ubuntu 18.04 Boost Version: 1.65.1.0 Regards, Ajay

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[release] Boost 1.79.0
by Marshall Clow 18 Apr '22

18 Apr '22

Release 1.79.0 of the Boost C++ Libraries is now available. These open-source libraries work well with the C++ Standard Library, and are usable across a broad spectrum of applications. The Boost license encourages both commercial and non-commercial use. This release contains numerous enhancements and bug fixes for existing libraries. For details, including download links, see <http://www.boost.org/users/news/version_1.79.0> You can also download directly from: <https://boostorg.jfrog.io/artifactory/main/release/1.79.0/> To install this release on your system, see <http://www.boost.org/doc/libs/release/more/getting_started/index.html> Thanks to everyone who participated in this release. -- The Boost Release Team Marshall Clow, Michael Caisse, Glen Fernandes

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Boost.Intrusive: getting the next element
by Gonzalo Arana 16 Apr '22

16 Apr '22

Hi, Given an element (contained in a list), how may I get the next one, without requiring access to the list itself? I only found this way to get the next element: auto iterator = list.iterator_to(value); ++iterator; return *iterator; But it requires access to the list itself. Best regards, -- Gonzalo A. Arana

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Boost.Text is looking for a (mini-)review manager
by Mateusz Loskot 15 Apr '22

15 Apr '22

Hi, A reminder from the review wizards: The Boost.Text library developed by Zach Laine is still looking for a (mini-)review manager, see details at: https://lists.boost.org/Archives/boost//2020/08/249594.php and https://www.boost.org/community/review_schedule.html Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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MySQL library scheduled for review
by Mateusz Loskot 15 Apr '22

15 Apr '22

Hi, A brief announcement from the review wizards: Following the proposal [1] and search for the review manager, formal review of the MySQL library [2] has been scheduled to take place between May 9, 2022 - May 18, 2022. Details and links available here https://www.boost.org/community/review_schedule.html We'd like to thank Richard Hodges for volunteering to act as the review manager, again! [1] https://lists.boost.org/Archives/boost/2022/03/252584.php [2] https://github.com/anarthal/mysql/ Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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[Math / Special Functions] Use more than one user_error function?
by Warren Weckesser 14 Apr '22

14 Apr '22

I am wrapping some boost special functions as NumPy "ufuncs" for the Python library SciPy, and I am setting a policy to control how errors are handled. For example, the wrapper of erf_inv (for C++ types float, double and long double) is wrapped as the function scipy.special.erfinv (i.e. the Python function is erfinv in the module scipy.special). The actual core instantiation of the function for type, say, double, in C++ that is called by the ufunc implementation is double erfinv_double(double x) { return erf_inv(x, special_policy()); } where erf_inv is the Boost function, and special_policy is created as template <class T> T user_domain_error(const char *function, const char * message, const T& val) { sf_error("erfinv", SF_ERROR_DOMAIN, NULL); return std::numeric_limits<T>::quiet_NaN(); } typedef policy< domain_error<user_error>, overflow_error<ignore_error> > special_policy; Note that the error handler is calling sf_error(), a function in the SciPy special library. The first argument is the name of the SciPy Python function. That function might generate a Python warning or set a Python exception, and the name displayed in the error message should be the name of the SciPy function, and not something like "boost::math::erf_inv[...]". This leads to the problem. The above code, with a hard-coded string "erfinv" passed to sf_error(), works for erfinv, but obviously I can't use the same implementation of user_domain_error for a wrapper of, say, tgamma_ratio. So the question is, can different policies be created that have different user-defined error handlers? Or is there a clever way to get the SciPy name into the user_domain_error() function? (I hope there is something simple--I am not a C++ guru, so I may have missed something obvious.) I am considering creating a mapping from some parsed version of the function argument of user_domain_error to the SciPy names. E.g. the function argument could be scanned for the occurrence of "erf_inv", and know that the name "erfinv" should be passed to sf_error(). A table of regex patterns with corresponding SciPy names might do the trick. But I'm wondering if there is a more elegant (and more maintainable) solution. Regards, Warren

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Re: [Boost-users] [boost] [release] Boost 1.79.0
by Glen Fernandes 14 Apr '22

14 Apr '22

On Wed, Apr 13, 2022 at 3:17 PM Andrey Semashev wrote: > > On 4/13/22 21:04, Vinnie Falco via Boost wrote: > > The thing that I absolutely LOVE about a new release of Boost, is that > > someone always reports a crashing bug just after the release is > > published: > > > > <https://github.com/boostorg/json/issues/692> > > We have a practice of adding post-release patches to release notes. Updated: https://github.com/boostorg/website/commit/0752dee32f149db385ea0f635886221b… Added /patches/1_79_0/0001-json-array-erase-relocate.patch and release notes updated. Glen

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Unlock / free a boost::asio::strand in beast?
by Markus Bonk 13 Apr '22

13 Apr '22

Hi, The application is using beast / websockets to communicate with a websocket server. A specific onread handler which is initially running on the stream strand needs to read another value from the websocket server to proceed. It sends a message and then waits on a future. This deadlocks the websocket communication. If instead of a strand a mutex were being used could unlocking the mutex before sending the message after the data that needs to be protected / requires synchronization has been already acquired and the resources would be available for the next handler. Is there any way of 'unlocking' the strand i.e. setting the state of the handler's thread so that 'isrunning_on_strand' = false and the stream can continue servicing the incoming messages? Thanks for any pointers. Markus ________________________________ Markus Bonk Senior Software Engineer [cid:3dconnexion_bd84aa85-40b4-4789-87b1-4c8f703d9ae6.gif] Clarita-Bernhard-Str. 18 81249 M?nchen Germany markus_bonk(a)3dconnexion.com<mailto:markus_bonk@3dconnexion.com><mailto:%7BE-mail%7D> www.3dconnexion.com<http://www.3dconnexion.com> Gesch?ftsf?hrer: Antonio Pascucci Sitz der Gesellschaft: M?nchen Registergericht: M?nchen HRB 99232 This email and any files transmitted with are from 3Dconnexion GmbH. The contents of this email and any attachments are confidential to the intended recipient. They may not be disclosed to or used by or copied in any way by anyone other than the intended recipient. If this email is received in error, please contact 3Dconnexion GmbH by calling +49 89 8974542-0 and then delete it. Please note that neither 3Dconnexion GmbH nor the sender accepts any responsibility for viruses and it is your responsibility to scan or otherwise check this email and any attachments. Any opinion expressed in this email are those of the individual and not necessarily those of 3Dconnexion GmbH. 3Dconnexion GmbH processes and stores for commercial purposes your personal data, collected upon your consent, in accordance with its privacy policy available at https://www.3dconnexion.eu/privacy.html, which has been drafted in accordance with Regulation (EU) no. 679/2016 and all applicable local data protection laws and regulations of the countries where the company operates. To revoke your consent or exercise all your rights with regards to personal data, please contact us at privacy(a)3dconnexion.com<mailto:privacy@3dconnexion.com>.

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Reading a large compressed .gz file without uncompressing it
by bharath pagadala 05 Apr '22

05 Apr '22

Hi Team, My requirement is I want a read a large .gz file and stream data without uncompressing it. Does the boost library help me to achieve this. Is there any function in the boost library which help me stream data directly without uncompressing the input .gz file. Please respond on this thank you in advance. Cheers, Bharat Pagadala

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The Boost Statechart Library AND boost::bind
by Jinlong Shen 05 Apr '22

05 Apr '22

Can the statechart library be updated to treat the boost::bind warning about namespace. See here for details. https://stackoverflow.com/questions/53203970/why-boostbind-insists-pulling-…

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[Nowide] Nowide and Property Tree file IO
by William Kappler 03 Apr '22

03 Apr '22

I'm trying to sidestep some issues with unicode filenames on Windows (MSYS64) using Boost.Nowide. Specifically, my program operates in UTF-8, and providing that to std/Boost functions yields incorrect filenames due to them being interpreted as UTF-16 (or something along those lines). However, the primary functions I have issues with are from Boost.PropertyTree. Specifically, read_json and write_json. These functions don't seem to be Nowide-friendly. I tried just calling boost::nowide::nowide_filesystem() before my json calls, hoping it would work; it did not, I got the same mangled filenames. My next thought was to see if a nowide stream could be substituted into the stream-taking variants of read_json/write_json; it cannot be, they aren't compatible. The only option that seems to leave is something along these lines: https://stackoverflow.com/a/21537818, but using Nowide to read in the file. That adds a lot of steps (and possibly memory usage). It feels like I'm missing something. Any suggestions would be appreciated. Thanks in advance. :-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:- *William E. Kappler II* Software Designer and Programmer william-kappler.com

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boost python AttributeError
by Chien-Yu Chen 03 Apr '22

03 Apr '22

hi I followed the basic boost python examples, both hello_ext.greet() and hello.World() and both are giving me AttributeError error, like AttributeError: module `hello` has no attribute 'greet' dumpbin does show that I have PyInit_hello exported out. Please let me know if I am doing something wrong as this should be trivial. thx -- Any MicroSoft extension file will directly go to trash without any warning and regret.

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Fwd: Concatenated input streams
by Robert Dodier 29 Mar '22

29 Mar '22

Hi, I'm interested in working with an input stream which comprises multiple input streams. The resulting stream comprises all of the input from the first stream (until EOF), then all of the input from the second, etc. For what it's worth, such an input stream is called a concatenated input stream in at least one other context (namely Common Lisp). The input streams in question are file input streams, although conceptually I don't know if that changes anything. I am hoping to find something equivalent to $ cat file1 file2 file3 ... > alldata and then reading alldata. Is there a Boost class which implements such a thing? I know that this is a pretty simple concept, and therefore it's just a small matter of programming, but I'm hoping that someone has already worked out the details. If there is such a thing in some library other than Boost, I would be interested to hear about that too. Thank you for your time, I appreciate your help very much. Robert Dodier

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[Boost.Asio] Can I move io_context away while having sockets bound to it?
by B Aleck 22 Mar '22

22 Mar '22

You created serveral sockets and bound them to an io_context Is it safe to std::move the io_context away? Will those sockets be affected, or even be invalidated?

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Curious definition of beast::file_mode::append
by Senthil Cheetancheri 18 Mar '22

18 Mar '22

Hi All, The current definition of append seems to be identical to that of write. Both are defined as follows: 1. Create a new file if it doesn't exist. 2. Truncate to zero bytes, if it exists. The comment for append says, "The current file position shall be set to the end of the file prior to each write." However, if the file is always truncated to zero, implementing the above comment achieves nothing significant. Shouldn't append simply open an existing file or create a new one for writing and set the file-pointer to the end of the file? This will also obviate the need for append_existing. Following the same line of reasoning for write: The comment says that this mode permits random-access reading and writing for the specified file. However again, if the size is always truncated to zero bytes, random-access reading or writing becomes a moot point. On the other hand, if write is defined not to truncate (as I expected originally), it will obviate the need for write_existing as well. Am I misunderstanding these definitions? Is there a sound reason behind the current definitions? Thanks, Senthil.

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numeric_cast should work with enum's
by Frederick Virchanza Gotham 16 Mar '22

16 Mar '22

(Sometimes Gmail changes white space so I hope this post is indented properly) I think that "numeric_cast" should be able to cast to and from enum types, so that it can be used as follows: #include <cstdint> #include <iostream> using std::cout; using std::endl; enum class Frog { Blue, Yellow, Pink = 0xFFFFu }; enum class Toad : std::uint8_t { Purple, Orange = 0x7f }; int main(void) { try { numeric_cast<Toad>( Frog::Pink ); } catch(std::exception const &e) { cout << e.what() << endl; } std::uint32_t my_32_bit_var = 0xffffffffU; try { numeric_cast<std::uint16_t>(my_32_bit_var); } catch(std::exception const &e) { cout << e.what() << endl; } try { numeric_cast<std::uint8_t>( Frog::Pink ); } catch(std::exception const &e) { cout << e.what() << endl; } try { numeric_cast<Toad>(0x1FFu); } catch(std::exception const &e) { cout << e.what() << endl; } } In order to achieve this behaviour, I've created my own "numeric_cast" in the global namespace as follows: #include <type_traits> // is_enum, underlying_type #include <boost/numeric/conversion/cast.hpp> // numeric_cast template<bool T_is_an_enum, typename T> struct numeric_cast_helper { typedef T type; }; template<typename T> struct numeric_cast_helper<true, T> { typedef typename std::underlying_type<T>::type type; }; template<typename A, typename B> A numeric_cast(B const b) { return static_cast<A>( boost::numeric_cast<typename numeric_cast_helper<std::is_enum<A>::value, A>::type> ( static_cast<typename numeric_cast_helper<std::is_enum<B>::value, B>::type>(b) ) ); } Should the Boost Numeric library be changed so that numeric_cast can work with enum's?

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[release] Boost 1.79.0 beta 1 released
by Marshall Clow 16 Mar '22

16 Mar '22

Boost release 1.79.0 beta 1 is now available at: <https://boostorg.jfrog.io/artifactory/main/beta/1.79.0.beta1/source/> The SHA256 checksums are as follows: 8985105623f48d55be01076d98ca4e7a8cb548a8d7f9ad0e1fc3c710d2c75fcf boost_1_79_0_b1.tar.bz2 4b58e4d3b6ff1176b3c6cb9eec496c1f6d2535270e97ec140da533d68766ca39 boost_1_79_0_b1.tar.gz 4d05b458cd039afe86003cf7e1e6c3a358b5b2d031892e620eedc344ab200246 boost_1_79_0_b1.7z 768875ad5c77763445e8b119072cfa1e64854b071a353dd44c3c73ff46df910b boost_1_79_0_b1.zip For details of what's in the release, see <https://www.boost.org/users/history/version_1_79_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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container: static_vector and type traits
by MM 15 Mar '22

15 Mar '22

Hello Should static_vector be of standard layout and/or trivially copyable? depending on the element type I see this outputs false std::cout << std::is_standard_layout_v<boost::container::static_vector<char,32>> << std::endl; std::cout << std::is_trivially_copyable_v<boost::container::static_vector<char,32>> << std::endl; Rds,

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Boost.ASIO SSL Version?
by Osman Zakir 10 Mar '22

10 Mar '22

What version of OpenSSL does Boost.ASIO use? And may I suggest to consider upgrading to the latest version if that hasn't been done already (if it's not too much trouble)? I tried to use version 3.0.1 (LibreSSL 3.4 is already out but according to openssl.org, their official latest version is 3.0.1? I'm not sure.) with this project of mine: https://github.com/DragonOsman/currency_converter and got these errors: " 1>C:\local\boost_1_78_0\boost\asio\ssl\impl\error.ipp(43,28): error C4996: 'ERR_func_error_string': Since OpenSSL 3.0 1>C:\local\boost_1_78_0\boost\asio\ssl\impl\context.ipp(54,29): error C4996: 'RSA_free': Since OpenSSL 3.0 1>C:\local\boost_1_78_0\boost\asio\ssl\impl\context.ipp(60,28): error C4996: 'DH_free': Since OpenSSL 3.0 1>C:\local\boost_1_78_0\boost\asio\ssl\impl\context.ipp(962,29): error C4996: 'd2i_RSAPrivateKey_bio': Since OpenSSL 3.0 1>C:\local\boost_1_78_0\boost\asio\ssl\impl\context.ipp(965,29): error C4996: 'PEM_read_bio_RSAPrivateKey': Since OpenSSL 3.0 1>C:\local\boost_1_78_0\boost\asio\ssl\impl\context.ipp(978,13): error C4996: 'SSL_CTX_use_RSAPrivateKey': Since OpenSSL 3.0 1>C:\local\boost_1_78_0\boost\asio\ssl\impl\context.ipp(1056,9): error C4996: 'SSL_CTX_use_RSAPrivateKey_file': Since OpenSSL 3.0 1>C:\local\boost_1_78_0\boost\asio\ssl\impl\context.ipp(1122,23): error C4996: 'PEM_read_bio_DHparams': Since OpenSSL 3.0 " Or should I stick to version 1.1.1m? Thanks for any replies.

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Vertical slopes and Cubic Hermite Interpolation
by Cory Riddell 08 Mar '22

08 Mar '22

I'm reading about boost::math::interpolators::cubic_hermite and the constructor takes three arguments: x values, y values and slopes (dy/dx). Can this library be used when the slope at a point is vertical? If so, how do you specify that? I tried std::numeric_limits<double>::infinity() but that doesn't work. Cory

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