November 2014 - Boost - lists.preview.boost.org

[sort] Review of the Sort library by Steven Ross
by Edward Diener 14 Nov '14

14 Nov '14

As review manager I am forwarding this review sent to me: - What is your evaluation of the design? - What is your evaluation of the implementation? Design an implementation look good to me. Spreadsort has a clean interface and the code is readable. I tried the algorithm out a few years ago in a project at work (our product in the EDA industry) for sorting 32-bit {x,y} coordinate data cast to a 64-bit integer, and for sorting 32-bit values within scanlines. The speedup was about 1.8x that of std::sort() for ~100M values. This translated into a 10-20% overall runtime reduction in that tool, with only a few lines of code changes. - What is your evaluation of the documentation? I haven't read through the documentation in detail, but I have read through the code and the comments so I feel I understand the basics of how the sorting algorithm works. - What is your evaluation of the potential usefulness of the library? I would say this library is very useful for specific tasks involving large datasets that need to be sorted, especially in cases where the data is already partially sorted and contains many duplicate values. For example, it could be useful for EDA applications, computational geometry, some types of databases, etc. It may be a fairly narrow user base but I think it could add significant value. - Did you try to use the library? With what compiler? Did you have any problems? I built and tested spreadsort on both linux/gcc and Windows/MSVC++. I was never successful in running the tests in Cygwin. It seemed to work as expected when I tried using it inside an EDA tool and caused no problems. - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? I spent some hours reviewing the algorithm a few years ago, and I provided Steve with feedback to improve the code. I was mostly interested in the integer sorting aspect at that time, but did experiment with floating-point numbers as well. I read through the code again recently to familiarize myself with it. - Are you knowledgeable about the problem domain? I would say that I'm knowledgeable of applications and uses of sorting large datasets, and algorithms in general. I don't have any specific experience in developing or testing sorting algorithms. - Do you think the library should be accepted as a Boost library? Yes, I believe Steve has put in enough work to make this a well designed, tested, and documented library. There are real numbers to show the performance improvements over other sorting algorithms. If this was part of Boost, I would probably use it in our product at my company. Frank Gennari

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which submodule are boost headers in?
by Robert Ramey 13 Nov '14

13 Nov '14

This is making me feel really dumb. I want to remove a header in the /boost/ directory. This has been superseded by a header of the same name in the serialization library. boost/strong_typedef.hpp I expected to find a sub-module in modular boost which I can just select, get permission to make changes and upload my change - just remove this file. But I don't find a sub-module which seems to contain this header. So I need some help. Actually the simplest would be for someone who understands this and has appropriate privileges to just do the dirty work for me and remove the file. Failing that, someone can explain the procedure for finding the file, and getting the requisite privileges. Robert Ramey -- View this message in context: http://boost.2283326.n4.nabble.com/which-submodule-are-boost-headers-in-tp4… Sent from the Boost - Dev mailing list archive at Nabble.com.

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[site] uBLAS documentation page link is broken
by Renato Florentino Garcia 13 Nov '14

13 Nov '14

The uBLAS documentation link[1] on Boost libs documentation page[2] is broken. The previous released version[3] is yet working nevertheless. Regards, Renato Garcia [1]: http://www.boost.org/doc/libs/release/libs/numeric/ublas/doc/index.htm [2]: http://www.boost.org/doc/libs/ [3]: http://www.boost.org/doc/libs/1_56_0/libs/numeric/ublas/doc/index.htm

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[smart_ptr] explicit instantiation of boost::shared_ptr
by Petr Machata 12 Nov '14

12 Nov '14

Hi there, I got a bug report that the following code doesn't compile: #include <boost/tr1/memory.hpp> template class boost::shared_ptr<int>; int main(int, char**) {} The errors this gives under GCC 4.9 are as follows: In file included from /usr/include/boost/shared_ptr.hpp:17:0, from /usr/include/boost/tr1/memory.hpp:56, from foo3.cc:1: /usr/include/boost/smart_ptr/shared_ptr.hpp: In instantiation of 'typename boost::detail::sp_array_access<T>::type boost::shared_ptr<T>::operator[](std::ptrdiff_t) const [with T = int; typename boost::detail::sp_array_access<T>::type = void; std::ptrdiff_t = long int]': foo3.cc:2:23: required from here /usr/include/boost/smart_ptr/shared_ptr.hpp:663:22: error: return-statement with a value, in function returning 'void' [-fpermissive] return px[ i ]; This in particular is with boost 1.54. The problem is however present on master as well, where it also gives more errors relating to boost/core/demangle.hpp that I didn't look into. I went ahead to do some investigation in case the issue ends up being trivial. We can't use enable_if to disable a particular member function. Not unless it's a template. Making it a template would lead to a code like this: template <class U = T, class V = boost::disable_if <boost::is_void <boost::detail::sp_array_access< U >::type>, U>::type> boost::detail::sp_array_access< T >::type operator[] (etc. etc.); ... which is not C++98, and I don't have ideas how to C++98-ify it while also having it do what we want without breaking API. (The indirection through U may not be necessary, I'm not in fact sure, but that doesn't change anything.) One way that I can see is extracting element_type * px to a base class (say, boost::detail::sp_operator_at) that either does or does not define operator[] (which would then use the px). But that implies some amount of code motion, and not knowing what your position would be, I didn't want to blindly go ahead and start moving stuff around. So, would a patch to the effect described above be possibly acceptable? Thanks, Petr.

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[Fusion] Lots of test failures on develop
by Louis Dionne 12 Nov '14

12 Nov '14

I'm getting a lot of test failures on the develop branch of Fusion on OS X. There are too many to paste the output here. Note that master is just fine. Are the unit tests being run automatically each time a pull request is merged? Louis

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Boost.Build: new tutorial
by Vladimir Prus 12 Nov '14

12 Nov '14

Back in 2009, Boris Schäling wrote a Boost.Build tutorial that many deemed to be better than the tutorial in the official documentation. It took quite some time, but it's now part of Boost.Build, here: http://www.boost.org/build/tutorial.html I'd appreciate any comments. Note that previously, I planned to integrate this tutorial with the boostbook documentation. It's becoming clear that there's just no time for that, and the tutorial is added as HTML page. I haven't decided yet what to do with old tutorial in boostbook sources. -- Vladimir Prus CodeSourcery / Mentor Embedded http://vladimirprus.com

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[multi_index] Doc suggestion.
by Mostafa 11 Nov '14

11 Nov '14

Not being able to mutate elements through non-const iterators is surprising enough that I forget about it every time I use Boost.MultiIndex. Part of the reason for this is that this information is buried under section "multi_index/doc/tutorial/basics.html#seq_indices". I suggest that the following paragraph: "That is, iterators of a sequenced index (of all types of indices, actually) point to constant elements. This limitation might come as a surprise, but it is imposed by the way multi_index_containers work; if elements were allowed to be changed in this manner, we could introduce inconsistencies in other ordered indices of the multi_index_container. Element modification can nevertheless be done by means of update operations." be moved under "multi_index/doc/tutorial/basics.html#iterator_access" as a call-out.

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Boost Incubator Status Report
by Robert Ramey 11 Nov '14

11 Nov '14

Felix Uhl wrote > On 28/10/2014, Rob Stewart wrote: > > >Currently, I am documenting the first version of the library to make it >>available on the Boost Library Incubator website, > > I can hear Robert yelling, "Yes!" Yes! The experience so far with the incubator is very interesting. Here are couple of observations. a) I anticipated more submissions since the process seems so easy and the bar is very low. As a practical matter the requirements boil down to having code, tests, documentation which implies some examples. There are no restrictions of format of any of these things. But if you troll the net looking for libraries very few library ideas fulfill these requirements. It turns out that fulfilling even these modest (in my view) requirements is more than many people find necessary. b) The quality of the submissions is a lot better then I had anticipated. All of them are credible, serious efforts which are worthy of serious consideration for inclusion in Boost. That's not to say that all would eventually be accepted as I have only given them a cursory examination. c) There are very few comments on the pages of the website and on the library pages. So far there is only one formal review. I'm sort of disappointed in this. It goes to our problem in getting enough reviews in general. The one review (boost compute) was from one who downloaded and tested the library, liked it, and included it in production. Of course the review was very positive. I would hope to see more of this in the future. d) To support more reviews, I have on my todo list to keep track of who invokes the download/repo links and match them up with the users email address and send out a gentle reminder that if he spent the time to look at and consider the library, he should either comment or add a formal review. I would also like to see some of the posting on this list regarding library proposals to moved to the library comments page. Another alternative would be to link from the library comment page to the developer's list thread(s) which touch upon the library. In any case, I want to see more activity in this area. Any of these require good experience with wordpress and some available time - so I don't see these happening soon. e) I would like to see a little more support from Boost Steering Committee on this effort. Specifically I would like to see the Announcement that Boost endorses the Boost Library Incubator (www.blincubator) packaged and distributed as press release so that it would show up in places like Dr Dobbs Journal. (http://www.drdobbs.com) and isocpp.org (http://isocpp.org). It is a great disappointment to me that in spite of a fair amount of effort, I've been unable to get these sites (among others) to announce the Boost endorsement of Boost Library Incubator. Finally - By next monday, I'll have in place a new facility. This is support on the library page whereby companies which have interest in a particular library will be able to contact the library author in order to offer financial sponsorship for his efforts. Companies which do this will be able to ask for special features and/or extensions, custom versions, extra support or anything they want. Authors will have the option of placing sponsors logos and links on their library pages. This will offer developers of open source the first opportunity in history to be compensated as the rock stars we are. Thanks for everyone for help so far in promoting the Boost Library Incubator. Please continue your efforts. Robert Ramey -- View this message in context: http://boost.2283326.n4.nabble.com/Boost-Incubator-Status-Report-tp4668747.… Sent from the Boost - Dev mailing list archive at Nabble.com.

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Please welcome Nevin Liber as a list moderator
by Beman Dawes 11 Nov '14

11 Nov '14

Nevin has been a long-time Boost Users list moderator, C++Now participant, and C++ committee member. He has graciously agreed to help moderate the Boost developers list. Please welcome Nevin as a list moderator! --Beman

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[git][flyweight] something messed up with master and develop branch
by Joaquin M Lopez Munoz 11 Nov '14

11 Nov '14

Dear Git connoiseurs: I've realized that my master and develop branches at boostorg/flwight appear collapsed: https://github.com/boostorg/flyweight/network Yet I am seemingly able to treat them separately: commit to develop, test, merge to master etc. The only weird thing is the diagram above and the fact that the commit log in master doesn't have the usual "Merge branch 'develop'" commits: https://github.com/boostorg/flyweight/commits/master Any clue what's going on? Thank you! Joaquín M López Muñoz Telefónica

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