- Boost - lists.boost.org

[algorithm] Removal of preference to std implementation
by Rob Conde 10 May '15

10 May '15

Marshall/Others-in-the-know, In boost algorithm change set 4dac507b773cf4a82727703ddffa2b36c42ab814, the code which uses std version of algorithms when available was removed. I'm curious about the motivation for this change. I can guess at a few potential reasons, but I figure you can just share the real reason. This change potentially explains a performance regression in my code so I'm just trying to understand the motivation before I make any code changes. Thanks! Rob Conde

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[testing] Add a tester with hidden visibility
by Andrey Semashev 09 May '15

09 May '15

Hi, Is it possible to add a tester that enables hidden visibility (- fvisibility=hidden -fvisibility-inlines-hidden) when building and testing Boost? I believe, a single tester on Linux+GCC would be enough to discover most issues related to symbol visibility. The reason I'm asking is that I believe Boost should support building with hidden visibility by default. This mode allows more optimizations and does not export unintended symbols from libraries. I've set hidden visibility for Boost.Log (in develop) and, as I understand, Robert is doing a similar change in Boost.Serialization. However, when building 1.58 with hidden visibility for my project I found out that not all libraries work well with that setting. What do you think about it?

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Re: [boost] Windows XP support survey
by Thomas Trummer 07 May '15

07 May '15

The sad reality in a lot of industries is that we still have to support Windows XP for the foreseeable future. Though, I understand the desire to drop support for it. Believe me, everyone would be more than happy to just require Windows 7 as default and be done with it. However, it is hard to convince costumers to make the switch when there is only risk and no tangible benefit attached to it. In addition to this we do have the problem that we control complex (and expensive) hardware that consists of components that don’t have drivers for Windows 7 because the manufacturer discontinued them. For these people the end of support from Microsoft isn’t really an argument since the computers are not connected to the Internet and continue to work fine, not to mention that you can still buy extended support from Microsoft. The huge outcry from the C++ community when Microsoft wanted to drop support for XP in Visual Studio should be a clear indicator that a lot of people livelihoods still depend on it. Unfortunately since then the install base hasn’t really shrunken too much. So even Visual C++ 2015 will continue to support it. So, as long as a Visual C++ version supported by Boost can build for Windows XP and there isn’t a significant cost attached to it, Boost should also continue to support Windows XP.

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Re: [boost] Windows XP support survey
by Andrzej Horoszczak - Billon 07 May '15

07 May '15

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Re: [boost] Interest in a container which can hold multiple data types?
by James Armstrong 07 May '15

07 May '15

Sorry about the README file, I pretty much just uploaded what I had to github so people can grab the source. Admittedly, things there are lacking. I'll work on filling out the readme with some instructions hopefully today. The main difference between this and a container of boost:any is that the container of boost::any still is a container of one data type, just being that one data type is a very flexible one. This container natively supports insertion of different data types. So, you could do, int my_int = 5; double my_double0 = 9342.132; double my_double1 = 987.654; std::string my_string("This is a string."); std::vector<double> my_vec; my_vector.push_back(123.456); omni my_container; my_container.push_back(my_int); my_container.push_back(my_double); my_container.push_back(my_string); my_container.push_back(my_vector); and the container happily stores the data. You can then access the data through iterators //access all doubles for (auto itr = my_container.begin<double>(); itr != my_containert.end<double>(); ++itr) { std::cout << *itr << std::endl; } or through specifying the data type and index //get the 0th element string std::cout << my_container.at<string>(0) << std::endl; -- James Armstrong

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[lambda] Addressing pull requests
by Edward Diener 07 May '15

07 May '15

The maintainer for lambda in the libs/maintainer.txt list is Jaako Jarvi, who is the original author. But I see others who have made changes to the library. So I am wondering if anyone is still actively maintaining the library. There are a number of pull requests for lambda, related to updating the code for type_traits Version2, by John Maddock and myself. Is someone handling these ?

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Arguing about names in Boost libraries
by Edward Diener 06 May '15

06 May '15

What is wrong with the people commenting on libraries for Boost who are so concerned about the names being used ? We are talking only about C++ identifiers and yet there are now endless discussions where people disagree on names or argue that some name is not what they want or that they like some other name, with a list of names that they find adequate. This is irrelevant. There is something mentally wrong about all those peoples spending endless amounts of time around this issue. I notice this does not happen nowadays for just one library but for ever single library, or proposed library, which is mentioned on this mailing list. Is this the way all of you people actually work in your daily jobs, or on your own projects, spending hours and days arguing with others about C++ identifiers for every little thing ? Are you not aware of the absurdity of your endless remarks ? Grow up ! Surely there are better things to do than carry on endlessly about some name, that is should be x or y or z or some other inane preferable list. It's time for somebody to say this, so I will do it. A C++ identifier name, as long as it is vaguely about what the functionality entails, is perfectly adequate. It does not have to satisfy everyone in the universe. Period !

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C++11 compilers and fenv
by Damian Vicino 06 May '15

06 May '15

Hi, I’m implementing the safe_float library (on c++11) proposed for the GSOC . I was planning to access FENV for detecting unsafe operations on the native floating point types and include some custom pre-post conditions for testing other floating types safety conditions. Conditions come from policies passed as template parameter to give users the possibility of chose their own set of safety conditions to be enforced. An example of the conditions that can be asked is enforcing overflows to infinite does not happen. An overflow to infinite can be detected by the FE overflow flag or because the addition of two finites numbers result in an infinite one. I just found today that clang++ does not support the pragma to use FENV yet. warning: pragma STDC FENV_ACCESS ON is not supported Googling a little I found out that neither does gcc. How are c++11 boost libraries dealing with these compiler issues? I got some options in mind: — Implement everything using custom detections, this will work in every compiler, but it will run slower for everyone too. — Finding a compiler with the support, implementing the library using the FENV, and assuming compilers will support it when the library is finished and reviewed. — Detect somehow the FENV pragma was not processed and have 2 implementations. No idea how to detect something like this. Had someone dealt with similar problem already? Is there a common approach? Best regards, Damian Vicino

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[ boost ] [ Trie ]
by Cosmin Boaca 06 May '15

06 May '15

Hello, I am interested in working at the Boost.Trie project which was started during GSoC 2013 and I am searching for someone who can give me some advice about what should I change / add to the current implementation, because I'm not too experienced in developing library code. However, I do not want do this during GSoC because I won't be available during the summer. I want to contribute during my spare time. If anyone thinks that can help me with this, please reply to this email. Thank you, Cosmin

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BenPope x86_64 Ubuntu issue at link time
by Vicente J. Botet Escriba 06 May '15

06 May '15

Hi, I'm getting this link error /usr/bin/ld: error: /home/ben/development/boost/test/build/results/boost/bin.v2/libs/thread/test/thread__constr__FArgs_p_lib.test/clang-linux-3.7~asan~c14_libc++/debug/threading-multi/threads/thread/constr/FArgs_pass.o: multiple definition of 'operator delete(void*)' /usr/bin/ld: /home/ben/development/llvm/trunk/install/release/bin/../lib/clang/3.7.0/lib/linux/libclang_rt.asan_cxx-x86_64.a(asan_new_delete.cc.o): previous definition here at http://www.boost.org/development/tests/develop/developer/output/BenPope%20x… I define it as follows #if defined _GLIBCXX_THROW void* operator new(std::size_t s) _GLIBCXX_THROW (std::bad_alloc) #elif defined BOOST_MSVC void* operator new(std::size_t s) #else void* operator new(std::size_t s) throw (std::bad_alloc) #endif { std::cout << __FILE__ << ":" << __LINE__ << std::endl; if (throw_one == 0) throw std::bad_alloc(); --throw_one; return std::malloc(s); } Is this a compiler issue, or is my definition of the operator new incorrect? Vicente

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