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Writing a stratum client using boost:asio
by Jan Willem Penterman 11 Feb '16

11 Feb '16

Hi, I'm trying to write a stratum client for a cryptocurrency mining application. The mining application connects to a stratum server to receive new work to mine on and submit solutions. The stratum protocol is a simple TCP based line protocol with JSON payload. Documentation here: https://mining.bitcoin.cz/help/#!/manual/stratum-protocol I've chosen to use boost::asio, as boost is already heavily used in the fork of the project I'm building the miner for. But I'm having difficulties to understand why my current implementation doesn't work. The basic flow is as follows: 1. connect to the server. this works 2. send subscribe method. this also works 3. authorize worker(s). doesn't work. 4. stratum server should start pushing new work periodically. doesn't work. 5. submit solution when found. not implemented yet. Without authorization, the server should still start pushing work. So I've skipped step 3 for now. The source code as I have it now is available here: https://github.com/Genoil/cpp-ethereum/blob/stratum/libstratum/ The output I get from this is as follows: i 12:19:14|<unknown> Connected to stratum server coinotron.com : 3344 i 12:19:15|<unknown> {"error": null, "id": 1, "result": [["mining.notify", "91d0025c5ea54509977e3475d065169e"], "080016D0", 4]} i 12:19:15|<unknown> Subscribed i 12:19:15|<unknown> { "id": null, "method": "mining.set_difficulty", "params": [32768]} i 12:19:15|<unknown> mining.set_difficulty i 12:19:15|<unknown> {"params": ["31065", "0xc09361c52e9dddd141040cc79c52eaed382e92c1dd350324c040482a4c4ac0fa","0x5a46dd85298b0beff65ccf3006c4b5d2f7fa6ca8a5885a7f2132714fe7a48602","0x0000000200000000000000000000000000000000000000000000000000000000", true], "id": null, "method": "mining.notify"} i 12:19:15|<unknown> mining.notify >From this I can conclude that the subscription call works. Then at the end of handleResponse, I simply queue up a new async_read_until to wait for the next line of JSON to come in from the server. This also kind of works, but the idea is that after a few seconds, new work should come in as a "mining.notify". This never happens. Can anybody explain what I'm doing wrong? Regarding the mining.authorize call on line 113. I've understood from the documentation that I can send that whenever I want, so I tried to do this immediately after the subscribe method returned. But if I do this, it a) doesn't return and b) all lines after "Subscribed" don't come in any longer. This is the second problem I'm trying to figure out. I'm using this as reference, but my Python is even worse than my C++ https://github.com/slush0/stratum-mining-proxy But when I run the binaries connecting to the same host (coinotron.com:3344), I do get new work coming in... Thanks for having a look at this.

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[ASIO] Newbie question - Bidirectional communication example
by Davies, John 11 Feb '16

11 Feb '16

For a simple explanation I have two processes that run on the same computer. Process 1 sends messages to Process 2 by putting the messages into an Interprocess message queue that Process 2 created. Process 2 sends messages to Process 1 by putting the messages into an Interprocess message queue that Process 1 created. The messages can be sent at any time and are not in response to each other. Very symmetrical. Now I want to put Process 1 and Process 2 on separate computers. My intent is to transfer the messages over TCP to the opposite computer without changing Process 1 or 2. So I thought I'd create two connector programs. Connector 1 creates a message queue that pretends to be the Process 2 message queue. When it gets a message, it send it over TCP the Connector 2. Connector 2 gets the message and puts it into the real Process 2 message queue. And the reverse if Process 2 has an outgoing message. I just can't find a good example to steal from. Everything I can find are more like Process 1 makes a request and Process 2 responds. So I think I have a fundamental misunderstanding of how ASIO works. ________________________________ The information contained in this message may be confidential and legally protected under applicable law. The message is intended solely for the addressee(s). If you are not the intended recipient, you are hereby notified that any use, forwarding, dissemination, or reproduction of this message is strictly prohibited and may be unlawful. If you are not the intended recipient, please contact the sender by return e-mail and destroy all copies of the original message.

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[Test] Funny Business with vector::at() out-of-range
by Merrill Cornish 11 Feb '16

11 Feb '16

I posted a question a couple of days ago: "Throws 'Escaping' both BOOST_CHECK_THROW and try{}". I found that BOOST_CHECK_EXCEPTION which is working for me elsewhere fails the same way. So, an out-of-range std::vector::at() seems to be the common element. In the definition of at(), the out-of-range response is handled by __throw_out_of_range_fmt(). When I looked up that one, I found void __throw_out_of_range_fmt(const char*, ...) __attribute__((__noreturn__)) __attribute__((__format__(__gnu_printf__, 1, 2))); in functexcept.h. To my admittedly less-than-expert eye, there doesn't seem to be an actual throw() here. On the other hand, the entire file are entries like this for various exceptions. There are a lot of Google hits for __throw_out_of_range_fmt, but they are for unresolved references in links, apparently caused by mixed version of libraries and object. Everything I've got is compiled linked for MinGW 64-bit, GCC 5.3.0, 64-bit --std=C++14, BOOST 1_60_1 64-bit so I get none of those errors. The problem I'm seeing with my test code is that wrapping a try{} around BOOST_CHECK_THROW shows that [1] the body of the try doesn't complete; but at the same time [2] not even a catch(...) can catch the presumed throw--as if a throw isn't actually being done. So, where did the throw go? Merrill Cornish

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[TEST] Throws "Escaping" both BOOST_CHECK_THROW and try{}
by Merrill Cornish 11 Feb '16

11 Feb '16

I'm running Windows 10, 64-bit; MinGW 64-bit; GCC 5.3 64-bit; and BOOST 1_60_1 Here is the relevant test code: [319] BOOST_CHECK_THROW(throw std::out_of_range("BOOST_CK_THROW test"), std::out_of_range); [320] try { [321] std::cerr << "arcsSize()" << std::endl; [322] empty1.arcsSize(Operand::DEFAULT_ARC_SET+1); [323] std::cerr << "arcsSize() did not throw" << std::endl; [324] }//try [325] catch (const std::out_of_range& ex) [326] { std::cerr << "out_of_range caught=|" << ex.what() << "|" << std::endl; } [327] catch (...) { std::cerr << "something else caught" << std::endl; } [328] [329] BOOST_CHECK_THROW(empty1.arcsSize(Operand::DEFAULT_ARC_SET+1), std::out_of_range); The original code was just the last line, line [329]. [319]-[327] was added in an attempt to characterize the problem. The error [329] got by itself was: terminate called after throwing an instance of 'std::out_of_range' what(): vector::_M_range_check: __n (which is 1) >= this->size() (which is 1) This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. SIGABRT intercepted; converted to exit(EXIT_FAILURE). arcSize() is implemented with std::vector::at() and the index is out-of-range, so it's supposed to throw std::out_of_range. That's what was detected, so why did it terminate the program? (The last line comes from my SIGABRT handler. Without it, the test executable ends up locked and can't be deleted.) Adding in all of the test lines shown above gives; [319] Operand_Test.cpp(319): info: check 'exception "std::out_of_range" raised as expected' has passed [321] arcsSize() terminate called after throwing an instance of 'std::out_of_range' what(): vector::_M_range_check: __n (which is 1) >= this->size() (which is 1) This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. SIGABRT intercepted; converted to exit(EXIT_FAILURE). Notice the explicit throw in line [319] is detected and handled properly. However, the arcSize() call from inside the try block throws, but is not caught by even catch(...) {}. Can anyone help me see what's going on here? Merrill Cornish

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[Container] Regarding Trac #11957, static_vector::max_size() is higher than the capacity
by Gagan Kumar 10 Feb '16

10 Feb '16

I tried a simple fix for https://svn.boost.org/trac/boost/ticket/11957 here https://github.com/boostorg/container/pull/37/files . Can someone please review it. Regards,Gagan Kumar

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Boost Variant Type Interfaces
by Ali Nakipoglu 09 Feb '16

09 Feb '16

Hi, In our project we are using boost, boost.variant very extensively. We was using methods provided by the library to interface with Variant types. Mainly : get<T>( variant ) for accessing stored values and variant.which() == Index for checking currently stored type. Overtime we realized we can improve this as : variant.getT() for accessing stored values much more nicer to write and variant.isT() or variant.which() == WHICH_T for checking currently stored type which does not depend on order of template paramters in the Variant definition. Also in some cases we wanted to be able to add type specific methods for example in our case we are using subscript operator to access recursively stored Variants variant[ "a" ].isT() or variant[ 0 ].asT() We generalized this solution for our project and published at https://github.com/FictionIO/WrappedVariant I would like to hear your comments. Do you think its a correct approach or useful? Any suggestions are welcome! Kind Regards, Ali

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[Multiprecision] Runtime assertion failure with clang++3.6.0 but not g++4.9.2
by mbw_bst＠mailbox.org 09 Feb '16

09 Feb '16

Dear all, this is my first post on this mailing list, so hopefully this will all be by the book. Executing the following minimal working example, which is supposed to calculate "3! == 6" via (1) a template function (2) a class template and save the result in a boost::multiprecision::mpz_int, results in unexpected behavior for clang++3.6.0, with the version of my boost library being 1.59.0. The program displays the correct result using g++4.9.2 however: #include <iostream> #include <boost/multiprecision/gmp.hpp> namespace bm = boost::multiprecision; template <std::size_t N> bm::mpz_int factorial() { return N * factorial<N-1>(); } template<> bm::mpz_int factorial<0>() { return 1; } template <std::size_t N> struct factorial2 { static const bm::mpz_int value; }; template<std::size_t N> const bm::mpz_int factorial2<N>::value = N * factorial2<N-1>::value; template<> struct factorial2<0> { static const bm::mpz_int value; }; const bm::mpz_int factorial2<0>::value = 1; int main () { std::cout << factorial<3>() << '\n'; std::cout << factorial2<3>::value << '\n'; return 0; } The output for clang, having been compiled via clang++ -std=c++14 -stdlib=libc++ -DNDEBUG -o main main.cpp -lgmp will result in: 6 0 However, omitting the NDEBUG flag will trigger an assertion failure: main: /usr/include/boost/multiprecision/gmp.hpp:1296: const mpz_t &boost::multiprecision::backends::gmp_int::data() const: Assertion `m_data[0]._mp_d' failed. Aborted (core dumped) Compiling the same program with g++4.9.2 (with or without "-DNDEBUG") yields the expected result: 6 6 What did I miss? Can this behavior indeed be traced down to Boost.Multiprecision, or does it have to do with the initialization order of static const class members? Or something else? Additionally, both variants work correctly with clang when using a built-in type like 'int'. Any help in understanding the problem on hand would be greatly appreciated! Best Regards, mbw

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Re: [Boost-users] [Multiprecision] Runtime assertion failure with clang++3.6.0 but not g++4.9.2
by mbw_bst＠mailbox.org 09 Feb '16

09 Feb '16

Hello again and thanks for your replies! Taking the following two statements into account: > For type int, the values are computed recursively at compile time, for a > user-defined-type the values are computed at runtime and you hit > initialization-order issues. > Seems to be that Multiprecision relies on static data that haven't > (necessarily) been initialized before your own static members. Works > fine > if the members are made non-static: Does that mean that, since a) boost::multiprecision::number<gmp_int> is not constexpr enabled, and b) static initialization can't happen at compile-time for user-defined types, that there is no way for me to initialize a variable of this type at compile-time? Does b) follow logically from a) ? I (believe to have) confirmed runtime-initialization by running valgrind, which showed the presence of dynamic memory allocations (and also jumps depending on uninitialized variables, which probably corresponds to the assertion failure). I am mentioning this because initially my little test program looked somewhat like this: #include <iostream> #include <vector> #include <boost/multiprecision/gmp.hpp> namespace bm = boost::multiprecision; template<std::size_t N> struct factorial { static const bm::mpz_int value; static void add_values(std::vector<bm::mpz_int>& vec) { factorial<N-1>::add_values(vec); vec.push_back(value); } }; template<std::size_t N> const bm::mpz_int factorial<N>::value = N * factorial<N-1>::value; template<> struct factorial<std::size_t{0}> { static const bm::mpz_int value; static void add_values(std::vector<bm::mpz_int>& vec) { vec.push_back(value); } }; const bm::mpz_int factorial<0>::value = 1; int main () { std::vector<bm::mpz_int> fac_table{}; factorial<10'000>::add_values(fac_table); std::cout << "Enter a number between 0 and 10'000 to calculate factorial:"; std::size_t number; std::cin >> number; std::cout << '\n' << number << "! == " << fac_table[number] << '\n'; return 0; } This still includes the "unsafe" static initialization of a user-defined type. However it compiles and runs via g++ -ansi -std=c++14 -O3 -Wall -Wextra -pedantic -static -save-temps -ftemplate-depth-50000 -DNDEBUG -o main main.cpp -lgmp -pthread This was what made me believe in the compile-time computation of the factorials in the first place, since using this version, valgrind does not show any dynamic memory allocation at all. On the other hand, I don't understand what's going on here really, especially since std::vector<> is supposed to allocate memory at run-time. Now I'm not sure whether the last example has anything to do with Boost.Multiprecision anymore, so while it would really make my day if you could help me better understand this, I will understand if this is not the right place to ask these questions. Thanks again for your replies so far, they have been of great help! Cheers, Max

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[gsoc16] ATTN: Project ideas deadline 19th Feb
by Niall Douglas 07 Feb '16

07 Feb '16

Tomorrow 8th February the application period for Google Summer of Code 2016 begins, and yet we have just *one* idea on the ideas page: https://svn.boost.org/trac/boost/wiki/SoC2016 We need *plenty* more if we are to be approved again this year as a Google Summer of Code org, the deadline for which is the 19th February. So if you have some project ideas and think you could mentor a student this summer, *please* consider adding a project idea to the ideas list or stepping forward with a list of Boost libraries or topics you'd be willing to mentor. Our thanks in advance. --- Boost C++ Libraries Google Summer of Code 2016 admin https://svn.boost.org/trac/boost/wiki/SoC2016

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download from sourceforge?
by Dan Bloomquist 07 Feb '16

07 Feb '16

I followed the link form boost.org and then through sourceforge. But sourceforge directed me to: <http://downloadbud.com/?adprovider=sourceforge_fwint&source=fw36_300x250-do…> The link is an executable! I've never heard of 'downloadbud'. Not a big deal for now, I'm running with 1.58. But I'd like to get the latest of spirit x3 before I ask questions on the spirit list that may not need asking. Is there another source for boost? Or, is this executable actually a safe extractor? Sourceforge handing over an exe when it should be be a package seems just wrong... Thanks, Dan.

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Boost and v8
by Daniel Burchardt 06 Feb '16

06 Feb '16

Hi, I try create v8 module to python used boost and i have problem: #include <iostream> using namespace std; #include <stdio.h> #include <stdlib.h> #include <string.h> #include "include/libplatform/libplatform.h" #include "include/v8.h" using namespace v8; const char* say_hello(const char* name) { return name; } #include <boost/python/module.hpp> #include <boost/python/def.hpp> #include <boost/python/class.hpp> using namespace boost::python; BOOST_PYTHON_MODULE(hello) { class_<V8, boost::noncopyable>("V8", no_init) .def("Initialize", &V8::Initialize).staticmethod("Initialize"); def("say_hello", say_hello); } compile process is ok but when i try import hello in python i see error: /hello.so: undefined symbol: _ZN2v82V810InitializeEv Thanks for help

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[MSM][MPL] Can't compile FSM with > 20 transitions (solved)
by Carlos Santos 05 Feb '16

05 Feb '16

Hi there, I am using boost v1.59 and I am having trouble in compiling a MSM state machine with more than 20 transitions. I followed the Q&A and added the following lines BEFORE any boost include: #define BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS #define BOOST_MPL_LIMIT_VECTOR_SIZE 30 // or whatever you need #define BOOST_MPL_LIMIT_MAP_SIZE 30 // or whatever you need but now instead of getting the previous error: error: wrong number of template arguments (21, should be 20) I get this one: /usr/local/include/boost/multi_index/tag.hpp:75:67: error: wrong number of template arguments (30, should be 20) mpl::vector<BOOST_PP_ENUM_PARAMS(BOOST_MULTI_INDEX_TAG_SIZE,T)>, I was just finishing this email when I found a solution. Adding only the following header #include "boost/mpl/vector/vector30.hpp" and explicitly declaring the transition table as a numbered mpl::vector (yep you have to count the rows...) struct transition_table : mpl::vector21< ... > solves the problem. Can you suggest me a better solution for this? Thanks! *Carlos Santos *

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[Test] BOOST_CHECK_EQUAL can't compare scoped enumerations
by Merrill Cornish 05 Feb '16

05 Feb '16

I'm running Windows 10, 64-bit, MinGW64 with GCC 5.3 64-bit, and BOOST_1_60_0 64-bit. Here is the stripped down version of what's failing: enum class UsedFor { NOTIFY_INPUT, CONST_INPUT, VAR_INPUT, NOTIFY_RESULT, VAR_RESULT}; UsedFor mUse = UsedFor::NOTIFY_INPUT; BOOST_CHECK(mUse == Operand::UsedFor::NOTIFY_INPUT); // BOOST_CHECK_EQUAL(mUse, Operand::UsedFor::NOTIFY_INPUT); If BOOST_CHECK_EQUAL() is commented out, BOOST_CHECK() complies and executes without error. However, // BOOST_CHECK(mUse == Operand::UsedFor::NOTIFY_INPUT); BOOST_CHECK_EQUAL(mUse, Operand::UsedFor::NOTIFY_INPUT); If BOOST_CHECK() is comment out, BOOST_CHECK_EQUAL() gets a template barf with the general comment, " template argument deduction/substitution failed:". Here are some of the complaints: D:\Boost_1_60_0/boost/test/tools/detail/print_helper.hpp:50:14: note: cannot convert 't' (type 'const DiGSE::Operand_Class_Test_Suite::Operand_Default_Constructor_Test::test_method()::UsedFor') to type 'std::_Setw' ostr << t; ^ D:/Program Files/mingw-w64/x86_64-5.3.0-posix-seh-rt_v4-rev0/mingw64/x86_64-w64-mingw32/include/c++/iomanip:208:5: note: candidate: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, std::_Setprecision) operator<<(basic_ostream<_CharT, _Traits>& __os, _Setprecision __f) D:\Boost_1_60_0/boost/test/tools/detail/print_helper.hpp:50:14: note: cannot convert 't' (type 'const DiGSE::Operand_Class_Test_Suite::Operand_Default_Constructor_Test::test_method()::UsedFor') to type 'std::_Setprecision' ostr << t; ^ At this point, it seems to be complaining about every io manipulator in existence. D:\Boost_1_60_0/boost/test/tools/detail/print_helper.hpp:50:14: note: mismatched types 'const std::piecewise_linear_distribution<_RealType>' and 'const DiGSE::Operand_Class_Test_Suite::Operand_Default_Constructor_Test::test_method()::UsedFor' ostr << t; Then it gets to the point of, apparently, dragging out all of the error messages it doesn't get to use very often: mismatched types*'const std::chi_squared_distribution<_RealType>' *and 'const DiGSE::Operand_Class_Test_Suite::Operand_Default_Constructor_Test::test_method()::UsedFor' ostr << t; ^ For the time being, I can simply use the explicit == check, but it looks like there's a problem here. Merrill Cornish

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[ANN] build2 - C++ build toolchain
by Boris Kolpackov 03 Feb '16

03 Feb '16

Hi, build2 is an open source, cross-platform toolchain for building and packaging C++ code. It includes a build system, package manager, and repository web interface. We've also started cppget.org, a public repository of open source C++ packages. This is the first alpha release and currently it is more of a technology preview rather than anything that is ready for production. We have tested this version on various Linux'es, Mac OS, and FreeBSD. There is no Windows support yet (but cross-compilation is supported). The project's page is: https://build2.org For those who need to see examples right away, here is the introduction: https://build2.org/build2-toolchain/doc/build2-toolchain-intro.xhtml Enjoy, Boris

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BOOST_LOG_TRIVIAL destination change
by Marc Paschover 02 Feb '16

02 Feb '16

I am working on a native Excel add-in (using XLW+), and I have been using Boost.Logging to output some diagnostic information, using BOOST_LOG_TRIVIAL. I would like to see this information in the Output window of Visual Studio. It seems like I somehow need to change the destination to boost::logging::destination::dbg_window, but I haven't been able to figure out a way to do this globally. Is there a way to do this? Thanks, Marc.

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Boost 1.60: boost::archive::iterators bug?
by Ernest Zaslavsky 02 Feb '16

02 Feb '16

Hi, Recently I've noticed that Base64 encoded data produced by implementation I use and implementation used by chromium project sometimes are not the same. It happened only once but it was enough for me to start worrying. The implementation is quite simple, and I guess borrowed it from somewhere, like SO or something. The code as following: using it_base64_t = bai::base64_from_binary<bai::transform_width<std::string::const_iterator, 6, 8>>; namespace bai = boost::archive::iterators; auto writePaddChars = (3 - input.length() % 3) % 3; std::string base64(it_base64_t(input.begin()), it_base64_t(input.end())); base64.append(writePaddChars, '='); simple and elegant. However, today I wrote a short test which takes a chapter from 'Alice's Adventures in Wonderland' and encodes it. As well, I used two different online encoder to encode the same text, both online encoders produce the same data. However above code produced the same code until character 1029 and then it is different from what it should be. Then later, it gets back to the same output as produced by online encoders. So my question is, any chance it is a bug in archive::iterators or it is something in the above code? Coliru is down, so, full code is here http://pastebin.com/JxMsMeV2 [Read More]<http://feeds.feedburner.com/~r/sizmek-blog/~6/1> [http://www.sizmek.com/Sizmek.png]<http://www.sizmek.com/>

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Building Boost 1.60 with VS2015 - 32 bit compiler is always selected
by Tiago Gehring 01 Feb '16

01 Feb '16

Hi, I'm trying to build Boost 1.60 with Visual Studio 2015 Update 1 in 64-bit mode but it seems to be ignoring the address-model=64 parameter and always builds a 32-bit version (I called b2 from the VS2015 Native tools for x64 command prompt): -- C:\Users\Tiago\code\boost_1_60_0>*b2 --toolset=msvc-14.0 variant=release link=static threading=multi address-model=64 architecture=x86* Performing configuration checks *- 32-bit : yes* - arm : no - mips1 : no - power : no - sparc : no - x86 : yes .... C:\Users\Tiago\code\boost_1_60_0>*cl* Microsoft (R) C/C++ Optimizing Compiler *Version 19.00.23506 for x64* Copyright (C) Microsoft Corporation. All rights reserved. usage: cl [ option... ] filename... [ /link linkoption... ] --- I saw in some ond discussion mentions to explicitly select the compiler version (I also have VS2010 and VS2012 installed) and environment variables batch file (in the project-config.jam file) but this didn't help either. Any help is really appreciated. Best regards, Tiago Gehring

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Re: [Boost-users] asio: implementing sock->receive like behavior eith async_read_some
by Bjorn Reese 01 Feb '16

01 Feb '16

On 01/28/2016 01:56 PM, Lloyd wrote: > I am using asio to read some data from SSL socket. asio tcp socket > implements a "receive" function, but ssl socket doesn't have an > implementation for "receive". In the code sample given below I wish to > implement this kind of behavior. > > eg > > { > ... > sock.async_read_some(...); > //continue the execution only after the above call finishes. > } Why are you using an asynchronous operation instead of simply calling ssl::stream::read_some()?

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C++Now 2016 Registration is Open
by Jon Kalb 28 Jan '16

28 Jan '16

Boost Users, Registration is now open for this year¹s C++Now (put on by Boost). http://cppnow.org/2016-conference/announcements/2016/01/28/registration-is-o pen.html The conference has sold out the last three years and is expect to do say again this year. Do not put off registering. Note that session submitters should not register until they receive instructions from Marshall Clow, our conference registrar. See you in Aspen! Jon

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asio: implementing sock->receive like behavior eith async_read_some
by Lloyd 28 Jan '16

28 Jan '16

Hi, I am using asio to read some data from SSL socket. asio tcp socket implements a "receive" function, but ssl socket doesn't have an implementation for "receive". In the code sample given below I wish to implement this kind of behavior. eg { ... sock.async_read_some(...); //continue the execution only after the above call finishes. } Whats the best way to do this? I tried "future" but the code blocks/dead locks some how, The I tried "spawn", but in this case also I don't know the method to wait for the coroutine to finish. Some tips are greatly appreciated. Thanks, Lloyd

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[Boost.LexicalCast] problem with 1.59 in Solaris
by dariomt＠gmail.com 28 Jan '16

28 Jan '16

Trying to compile file libs/date_time/src/gregorian/greg_month.cpp I get an error related to Boost.LexicalCast. I have reduced the problem to a minimal test case: #include <string> #include <boost/lexical_cast.hpp> void f(const char* s) { std::string s1(boost::lexical_cast<std::string>(s)); } My feeling is that this compiler has problems in the specializations for boost::detail::is_stdstring and boost::detail::is_char_array_to_stdstring. If I remove all those specializations the error goes away. I assume this is not the perfect solution because I guess this will miss some optimization of lexical_cast, but at least I can compile it this way :( Is there a better solution for this? Has this problem been fixed in 1.60? Error message (full instantiation stack available if needed): "/ThirdPartyLibs/boost/1_59_0/boost/lexical_cast/try_lexical_convert.hpp", line 146: Error: Ambiguous partial specialization for boost::detail::is_char_array_to_stdstring<std::string, const char*>, boost::detail::is_char_array_to_stdstring<boost::container::basic_string<boost::detail::CharT, boost::detail::Traits, boost::detail::Alloc>, const boost::detail::CharT*> and boost::detail::is_char_array_to_stdstring<std::basic_string<boost::detail::CharT, boost::detail::Traits, boost::detail::Alloc>, const boost::detail::CharT*>. "/ThirdPartyLibs/boost/1_59_0/boost/lexical_cast.hpp", line 42: Where: While instantiating "boost::conversion::detail::try_lexical_convert<std::string, const char*>(const char*const&, std::string &)". "/ThirdPartyLibs/boost/1_59_0/boost/lexical_cast/try_lexical_convert.hpp", line 134: Error: Ambiguous partial specialization for boost::detail::is_stdstring<std::string>, boost::detail::is_stdstring<boost::container::basic_string<boost::detail::CharT, boost::detail::Traits, boost::detail::Alloc>> and boost::detail::is_stdstring<std::basic_string<boost::detail::CharT, boost::detail::Traits, boost::detail::Alloc>>. "/ThirdPartyLibs/boost/1_59_0/boost/lexical_cast.hpp", line 42: Where: While instantiating "boost::conversion::detail::try_lexical_convert<std::string, const char*>(const char*const&, std::string &)".

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Regression with boost::python 1.60
by Emmanuel 28 Jan '16

28 Jan '16

Hello, I am not sure if this is the right place to do it, but I will try :-). I am having a regression in boost 1.60, I documented a small reproducer here: http://stackoverflow.com/questions/35056398/typeerror-when-iterating-over-a… Does anyone have a clue ? Cheers, Emmanuel

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[Odeint] Stiff System of differential equations
by jules 25 Jan '16

25 Jan '16

Hi all, I am currently working with a very large set of differential equations; it is a disease model with 20160 classes depending on which vaccine has been admnistered, history of infection, and age. To solve this I have been using the runge_kutta_fehlber78 controlled stepper with the integrate_const function. There I need to set the absolute_error, relative_error and the step_size. My issue is that the results from the solver seems to depend highly on the step_size and whether or not an observer is provided. Since the solver is adaptive I feel like the results should not depend on step_size and they should definitely not depend on the presence of an observer. My question is why would the results be related to the step_size or the observer? How would it be possible to get the same results regardless of the step_size and the presence of an observer? Could this be related to the system being stiff and if so how would it be possible to solve it (The jacobian is too complicated to calculate because of the population dynamics)? Any help would be appreciated. Many thanks, Jules

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BGL, shortest path between two nearby nodes in a huge graph
by Paolo Bolzoni 25 Jan '16

25 Jan '16

Dear list, I am a happy user of BGL, but recently I got stuck in a strange problem. I think I am missing the obvious, so I'll be happy to read the fine manual if it's the case. Just point me to the right direction. I need to find the shortest path between two nodes, for doing so I am using dijkstra with a custom visitor that stops the search (throwing an exception) when examine_vertex is called on the destination node. It worked fine, but it run strangely slow. After some profiling, it is clear that most of the time is used in the initialize_vertex function. The graph is fairly large, but the path I am looking for are fairly small (10 edges tops usually). It is possible to skip the initialize phase? Cheers, Paolo

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Some help for betweenness centrality for undirected weighted graph
by Xinran Wang 25 Jan '16

25 Jan '16

Hi everyone, this is from Jason. I am a new user of Boost library. Nowadays, I am doing a research about betweenness centrality measure. I am very confused about how to use boost to calculate the betweenness centrality. I need to calculate the centrality score based on a undirected and weighted graph. The following code is what I tried to do. But this block of code can only be used for calculated for unweighted graph. Could anyone here can offer me examples? Thanks for any reply. #include <boost/graph/betweenness_centrality.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/graphviz.hpp> typedef boost::property<boost::edge_weight_t, float> EdgeWeightProperty; typedef boost::adjacency_list < boost::listS, boost::vecS, boost::undirectedS, boost::no_property, EdgeWeightProperty > Graph; typedef boost::graph_traits < Graph >::vertex_descriptor vertex_descriptor; typedef boost::graph_traits < Graph >::edge_descriptor edge_descriptor; typedef std::pair<int, int> Edge; typedef std::map<Edge, int> StdEdgeIndexMap; void betweennessCentrality() { Graph g; Graph::vertex_descriptor a1 = boost::add_vertex(g); Graph::vertex_descriptor a2 = boost::add_vertex(g); Graph::vertex_descriptor a3 = boost::add_vertex(g); Graph::vertex_descriptor a4 = boost::add_vertex(g); Graph::vertex_descriptor a5 = boost::add_vertex(g); Graph::vertex_descriptor a6 = boost::add_vertex(g); Graph::vertex_descriptor a7 = boost::add_vertex(g); EdgeWeightProperty weight0 = 1; boost::add_edge(a1, a2, weight0, g); EdgeWeightProperty weight1 = 1; boost::add_edge(a1, a3, weight1, g); EdgeWeightProperty weight2 = 1; boost::add_edge(a2, a3, weight2, g); EdgeWeightProperty weight3 = 1; boost::add_edge(a3, a4, weight3, g); EdgeWeightProperty weight4 = 1; boost::add_edge(a4, a5, weight4, g); EdgeWeightProperty weight5 = 1; boost::add_edge(a5, a6, weight5, g); EdgeWeightProperty weight6 = 1; boost::add_edge(a5, a7, weight6, g); EdgeWeightProperty weight7 = 1; boost::add_edge(a6, a7, weight7, g); typedef boost::property_map< Graph, boost::vertex_index_t>::type VertexIndexMap; VertexIndexMap v_index = get(boost::vertex_index, g); std::vector< double > v_centrality_vec(boost::num_vertices(g), 0.0); boost::iterator_property_map< std::vector< double >::iterator, VertexIndexMap > v_centrality_map(v_centrality_vec.begin(), v_index); brandes_betweenness_centrality( g, v_centrality_map); }

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