- Boost - lists.preview.boost.org

Is there interest in a collection of call stack utilities?
by Aurelian Melinte 04 Mar '13

04 Mar '13

Hello, I have a collection of debugging/diagnostic utilities to inspect the run-time call stack and to resolve symbol information. The tools are currently C++11 code and support GNU-Linux and Windows. An overview is available at https://freeshell.de//~amelinte/call_stack_usage.html Is there interest for potential inclusion in boost? Thanks, Aurelian

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[persistent] Library preview: Persistent
by Stefan Strasser 04 Mar '13

04 Mar '13

Hi everyone, I'm thinking about finishing a library that was proposed a couple of years ago. It was pretty far along, and there is documentation available in the sandbox (somewhat outdated): https://svn.boost.org/svn/boost/sandbox/persistent/libs/persistent/doc/html… It is a library with the goal of storing C++ objects on disk, with an interface that is as close as possible to accessing regular C++ objects in memory. A very simple example could look like this: shared_loc<person> p=...; { transaction tx; p->name="..."; p->address="..."; tx.commit(); } It is based on Boost.Serialization, but automatically maintains a consistent state on disk (ACID transactions), which can be updated incrementally. Part of its code was moved to a library named Transact to work alongside other transactional resources (like memory) and is available in the sandbox: https://svn.boost.org/svn/boost/sandbox/transaction/boost/transact/ I'd like to know whether the boost community is still interested in such a library, and I suppose there are quite a few new people here so your comments are welcome as well. Thank You!

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GSOC 2013
by David Bellot 04 Mar '13

04 Mar '13

Only 2 projects have been proposed so far for GSOC 2013: wake up Boost ! https://svn.boost.org/trac/boost/wiki/SoC2013 :-D

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Re: [boost] Review managers wanted for augmented data structures
by Jonathan Wakely 04 Mar '13

04 Mar '13

8:08 PM, "Vadim Stadnik" wrote: > > Is there an alternative of not integrating advanced data structures into > STL? Why do they need to be put "into STL"? Why can't they exist in addition to it, or alongside it? > Augmented trees are non-standard due to different performance guarantees. They're non-standard because they're not in the standard. > A more reasonable and practical approach to STL would be to provide a wide > set of interchangeable containers and data structures with different > performance guarantees and allow programmers to make decisions about the > most suitable containers for specific applications. That's exactly what the STL is. The STL is about iterators and algorithms and concepts, not a fixed set of predefined containers. You've claimed the STL makes your containers "illegal" which is an odd claim that I can't agree with. Extending the STL with alternative containers is not just acceptable, I'm pretty sure it was intended by Stepanov et al. If your containers don't meet the complexity requirements of an Associative Container as defined in the standard that's fine, just don't claim it is an Associative Container and there shouldn't be a problem, surely. I don't understand why you think there are objections to non-standard containers. The containers in the standard are not suitable for all situations and are not the only choices, if there's a more suitable non-standard container then using it makes sense. This doesn't put the STL "under pressure", it proves its value, because existing algorithms work with both standard and non-standard containers if they model the required concepts.

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[locale] Memory leaks?
by Jookia 03 Mar '13

03 Mar '13

Hello! I've been debugging my application that uses Boost.Locale for the past five hours or so, and I've found it curious that it leaks memory. In order to stop it, I have to do a couple of weird things, such as including ICU in to my projects and calling u_cleanup at the end of my application. I also have to disable certain facets. I've put all this together in some source code, that by default won't leak, but uncommenting various parts will cause it to leak: // ---- BEGIN CODE ---------------------------------------------------- #include <boost/locale.hpp> #include <unicode/uclean.h> #include <iostream> using namespace boost::locale; using namespace std; int main() { generator gen; gen.categories( convert_facet | //collation_facet | // Various errors. //formatting_facet | // Various errors. //parsing_facet | // Various errors. message_facet | //codepage_facet | // Various errors. boundary_facet | calendar_facet | information_facet); locale newLoc = gen("zh_CN.GB18030"); locale::global(newLoc); cout.imbue(newLoc); // ios_info::get doesn't clean up after itself. //cout << as::date << time(0) << endl; // Do this at the end of the program to clean up resources. locale::global(std::locale("C")); cout.imbue(std::locale("C")); u_cleanup(); } // ---- END CODE ------------------------------------------------------ Dumping this as 'hello.cpp' and running this is how I'm debugging it: g++ hello.cpp -lboost_locale -licuuc && valgrind --leak-check=full --show-reachable=yes ./a.out Thanks, Jookia.

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[thread] why is 'thread_group' in 'boost/thread/detail'?
by pavel 03 Mar '13

03 Mar '13

as of 1.53 the docs say the 'thread_group' class is included by this instruction: #include <boost/thread/thread_group.hpp> http://www.boost.org/doc/libs/1_53_0/doc/html/thread/thread_management.html… whereas the actual file is not in the 'boost/thread', but accidentally is in 'boost/thread/detail' is that intentional? -- Pavel P.S. if you notice a grammar mistake or weird phrasing in my message please point it out

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Copyright notice update policy
by Mateusz Loskot 03 Mar '13

03 Mar '13

Hi, What is the policy of updating year in copyright notices? There are several pages ([1], [2], [3]) where copyright notice is explained, but without any notes on the year detail I found one thread [4] about copyright policy, but it discusses only copyrighting patches and fixes. I understand it may depend on local law in particular country, (i.e. it seems U.S. requires year [5]). However, without digging law backgrounds, I'd simply like to know what is Boost policy for the notice updates. For example, a file created in 2009 includes relevant copyright notice and in 2013 the file receives update. Is it required to update the copyright year to 2009-2013? [1] http://www.boost.org/users/license.html [2] http://www.boost.org/users/faq.html [3] http://www.boost.org/users/index.html [4] http://lists.boost.org/Archives/boost/2012/01/189315.php [5] http://www.contentious.com/2007/01/07/copyright-notice-is-the-year-really-n… Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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Review managers wanted for augmented data structures
by Vadim Stadnik 03 Mar '13

03 Mar '13

Hi all, At present, neither Boost library nor STL provides containers using augmented data structures. I suggest that the Boost community consider solving the challenging problem – how to extend STL by integrating advanced data structures. Is there an alternative of not integrating advanced data structures into STL? IMO, no, since it is equivalent to “STL must go”. C++ cannot ignore performance benefits provided by these data structures. On the other hand, advanced data structures can be implemented in many programming languages and this will make C++ less competitive. Augmented red-black trees could have been included in the very first version of STL. Why is it difficult and has not been done yet? The major obstacle for the integration is the C++ standard specification of computational complexities of single operations for containers and iterators. Augmented trees are non-standard due to different performance guarantees. At the same these data structures are beneficial for complex algorithms, since they offer a wider set of more efficient operations compared to standard containers. The typical performance improvement for one operation is O(log N) against O(N). For less efficient operations these trees normally provide running time O(log N) against O(1), which is good enough for many applications. The C++ STL will be under pressure as long as there are new data structures that offer better running time for user algorithms. Asymptotically, the main parameter that determines the running time of an algorithm is the total computational cost (to simplify the discussion we omit the effect of locality of reference). By definition, the total computational cost is the sum of costs of single operations multiplied by their frequencies. For a general purpose library, such as STL, it is impossible at the design stage to know frequencies of all container and iterator operations required in all possible user algorithms. A more reasonable and practical approach to STL would be to provide a wide set of interchangeable containers and data structures with different performance guarantees and allow programmers to make decisions about the most suitable containers for specific applications. Relatively small frequencies of inefficient operations do not have significant effect on the total computational cost of an algorithm. Thus, in principle, containers and iterators can provide even inefficient operation in order to support more unified interfaces and to improve the generality. The replacement of interchangeable containers offers the advantage of low development cost solutions to performance bottlenecks that arise due to enhancement requests and/or an increase in the number of elements processed by a user algorithm. Also, I’d like to note that the representation of sequences using augmented trees is a frequent point of confusion and probably the fact that was overlooked in the development of previous versions of STL. The general description of the method of augmenting data structures is given in the section 14.2 of this book T.H. Cormen, C.E. Leiserson, R.L. Rivest and C. Stein, Introduction to Algorithms, 2nd Edition, MIT Press and McGraw-Hill, 2001. The specific application of this method is provided for order statistic trees and interval trees. Unfortunately, there is no example of a sequence that stores unordered elements. Probably for this reason augmented red-black trees are often considered to be an improvement of search trees only. The efficient representation of sequences by the described red-black trees follows from the fact that augmenting by the counter of children nodes supports efficient mapping from non-negative integers into container elements. It works both for ordered and unordered containers with unique and multiple elements or keys. There are two libraries in the Boost review schedule: http://www.boost.org/community/review_schedule.html "STL Extensions" and "Countertree". None of them has as yet a review manager. The order of the reviews may not be significant. It is more important that at least one library pass the review. This would help integrating other advanced data structures. Are there Boost experts who could volunteer to take responsibility of review manager for any of these two libraries? Regards, Vadim Stadnik

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[exception][locale][timer] Pre-built library list in getting started guide.
by Daniel James 03 Mar '13

03 Mar '13

According to this ticket, building details are missing from the getting started guide: https://svn.boost.org/trac/boost/ticket/7324 Exception, locale and timer either need to be built, or have optional parts that need to be built. Please can appropriate people comment (in the ticket, not here) on what the libraries' need, so that I can fill in missing entries. If details are needed please write some text that I can copy and paste into the document, since you should be able to do a better job of writing it than I could. thanks, Daniel

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variant with shrink
by Niitsuma Hirotaka 03 Mar '13

03 Mar '13

boost::variant should be variant<int,int> => int variant<int,double> => double variant<int,boost::rational<int> > => boost::rational<int> variant<int,double,std::string> => variant<double,std::string> I wrote such extension https://github.com/niitsuma/variant_shrink Default generalize order is int < boost::rational<int> < float < double < std::complex<double> You can use other custom generalize relation by defining function object is_generalizable_to<Type,TypeTo>

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