February 2016 - Boost - lists.boost.org

[Fit] Purpose and Use Cases
by Artyom Beilis 17 Feb '16

17 Feb '16

Hello, Before the formal review begins I would really like to understand the purpose of Boost.FIT It isn't clear to me from the documentation what are the real world use cases? What can't be done today (for example composition) with simple C++11 lambdas? I'd love to see several real world examples and use cases of Boost.FIT - because at least for me I don't really understand why it is useful. Artyom

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Re: [boost] [block_ptr] Request for a review manager
by Bjorn Reese 17 Feb '16

17 Feb '16

On 02/04/2016 03:02 AM, Phil Bouchard wrote: > On the other hand I code completed the deterministic block_ptr in 2011 > and I am wondering if there is anything I am missing to get it through > the review process because this is one of the most important subject in > computer science: > https://svn.boost.org/svn/boost/sandbox/block_ptr/libs/smart_ptr/doc/index.… Do you have any performance measurements comparing block_ptr<T> with shared_ptr<T>? Btw, in the overview section you claim that shared_ptr<T> has to manage counters when it is dereferenced. I am not entirely sure that is correct.

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Boost.Python gsoc project
by Barun Parruck 16 Feb '16

16 Feb '16

Hi! I'm a student looking to get involved with the open source through boost. I was looking through the gsoc projects, and the one involving Boost.python, by Stefan Seefeld piqued my interest! I was wondering what sort of student you'd be looking for for the project, more details about what the project would entail, and what sort of programming competency test I would have to pass.

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stupid github question
by Robert Ramey 16 Feb '16

16 Feb '16

I want to add a contributer to the serialization library - but I can't figure out how to do this on github. I believe this has something to do with the fact that the serialization library is a sub project. It shouldn't be a big deal as I see there are already 31 contributors on the list - many of whom I don't recognise. Robert Ramey

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Alternative remove, erase, and partition algorithms
by Brent Friedman 15 Feb '16

15 Feb '16

Hello, I'd like to propose the following for inclusion in Boost.Algorithm. *semistable_partition* partitions a range into 'good' and 'bad' elements, as partition. 'Good' elements maintain their order, while 'bad' elements are left in unspecified order. stable_partition has either linear additional storage or performs 3NlogN move operations, whereas semistable_partition has constant memory overhead and at most 3N move operations. Requires forward iterators. *unstable_remove ( _if )* removes elements from a range but without maintaining element order. Performs at most N/2 moves as compared to N for remove. Requires bidirectional iterators. *unstable_erase* erases an iterator or range from a container ( as vector::erase ) without maintaining element order. Intuitively, this fills in the hole created by the erase operation by moving elements from the end. Limited to containers with bidirectional iterators (possibly random-access). The following documents describe and explore these algorithms: https://groups.google.com/a/isocpp.org/forum/#!topic/sg14/2uwOmXWqa2E (unstable_erase, unstable_remove) https://iterator.wordpress.com/2016/01/31/algorithms_0/ (unstable_remove, semistable_partition) I have been pursuing standardization, but it seems like there is value in getting community experience with these algorithms first in order to make for easier justification. -Brent Friedman

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[block_ptr] Works on MSVC + Boost.Pool bug
by Phil Bouchard 15 Feb '16

15 Feb '16

It looks like I was able to fix a bug which makes it run correctly under MSVC 2015 Express. Although I do have a crash in the boost::pool: Project2.exe!boost::simple_segregated_storage<unsigned int>::try_malloc_n(void * & start, unsigned int n, unsigned int partition_size) Line 333 C++ Project2.exe!boost::simple_segregated_storage<unsigned int>::malloc_n(unsigned int n, unsigned int partition_size) Line 363 C++ Project2.exe!boost::pool<boost::default_user_allocator_new_delete>::ordered_malloc(unsigned int n) Line 801 C++ Project2.exe!boost::singleton_pool<boost::detail::bp::pool,1,boost::default_user_allocator_new_delete,boost::details::pool::null_mutex,32,0>::ordered_malloc(const unsigned int n) Line 149 C++ Project2.exe!boost::detail::bp::pool::allocate(unsigned int s) Line 148 C++ Project2.exe!boost::detail::bp::block<int>::operator new(unsigned int s) Line 283 C++ Project2.exe!boost::detail::bp::make_block<int,int>(const int & t0) Line 520 C++ > Project2.exe!main() Line 119 C++ When I try this example: https://github.com/philippeb8/block_ptr/blob/master/example/block_ptr_test2… Thanks, -Phil

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Re: [boost] [block_ptr] Request for a review manager
by Peter Dimov 15 Feb '16

15 Feb '16

> Phil Bouchard wrote: > > > I added the new repository with the right folder structure: > > https://github.com/philippeb8/block_ptr > > You should update this to work with the latest Boost, because currently > block_base is abstract as it doesn't implement > > virtual void * get_untyped_deleter() = 0; It also doesn't work with -DBOOST_DISABLE_THREADS, which makes it inconvenient to test as it requires Boost.Thread.

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[dll] dbghelp.hpp in detail/winapi
by Andrey Semashev 14 Feb '16

14 Feb '16

Hi, I've noticed that Boost.Dll provides boost/detail/winapi/dbghelp.hpp header. boost/detail/winapi is the directory of Boost.WinAPI submodule, and I generally don't expect anyone else putting his header in that directory. Could dbghelp.hpp be moved somewhere inside boost/dll?

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Re: [boost] expected/result/etc
by Emil Dotchevski 13 Feb '16

13 Feb '16

On Wed, Jan 27, 2016 at 10:49 PM, Michael Marcin <mike.marcin(a)gmail.com> wrote: > So looking a few of these libraries/proposals I have a few things I'm > interested in. > > - Is it at least as good as a simple hand-rolled solution? > - Can you transport error codes through layers without knowing specifics > of an error? > > For the second Niall's outcome/result handles very well I think. > std::error_code and std::exception_ptr transport is good enough for almost > any reasonable type agnostic error transport. > Have you considered using Boost Exception? It lets you add arbitrary data to exception objects, even after they have been thrown, regardless of their type -- see http://www.boost.org/doc/libs/release/libs/exception/doc/error_info.html. The general idea is to adopt a strategy where the exception objects are augmented with any, even platform-specific relevant data, which then the catch site can analyze to choose the correct handling. Cheers, Emil

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[type_traits] ICE with msvc-12.0
by Steven Watanabe 13 Feb '16

13 Feb '16

AMDG I'm getting boost\type_traits\common_type.hpp(43): fatal error C1001: An internal error has occurred in the compiler. (compiler file 'msc1.cpp', line 1325) To work around this problem, try simplifying or changing the program near the locations listed above. which makes this toolset basically unusable. Oddly enough, I don't see this error in the regression matrix. Does anyone know what's up with this? > cl Microsoft (R) C/C++ Optimizing Compiler Version 17.00.50727.1 for x86 Copyright (C) Microsoft Corporation. All rights reserved. scratch.cpp: #include <boost/type_traits/common_type.hpp> int main() { boost::type_traits::common_type<int, char, long>::type x = 0; } > cd libs/type_traits > git log commit 1f3a3a1553dc316ed002354dce3ba3f081b2e102 Author: jzmaddock Date: Wed Jan 13 10:50:22 2016 +0000 Fixes for older GCC versions, see issue 11904. ... > dir boost ... 02/25/2015 08:26 PM <JUNCTION> type_traits [...\libs\type_traits\include\boost\type_traits] ... In Christ, Steven Watanabe

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