March 2009 - Boost - lists.boost.org

[Python] GSoC and Python 3.0 Support
by Haoyu Bai 11 Mar '09

11 Mar '09

Hi, I'm a student who has finished SWIG's Python 3.0 support in GSoC 2008. If Boost will participate in this year's Summer of Code, I'd like to contribute my knowledge of Python 3 migration to Boost.Python, by implement Python 3.0 support for it. Finally the users of Boost.Python would get 3.0 support smoothly. Is that worth for a GSoC project? Any interesting? Thanks! -- Haoyu Bai

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Compiling error with VC8
by Christophe Henry 11 Mar '09

11 Mar '09

Hi, I just got a strange compiling error while testing Msm with VC8. If I write: template <class StateType> typename ::boost::enable_if< typename ::boost::mpl::and_<typename ::boost::mpl::not_ <typename has_exit_pseudo_states<StateType>::type>::type, typename ::boost::mpl::not_ <typename is_pseudo_exit<StateType>::type>::type >::type,BaseState*>::type I get : error C2770: invalid explicit template argument(s) for '`global namespace'::boost::enable_if<is_pseudo_exit<StateType>::type,BaseState*>::type boost::msm::state_machine<Derived,HistoryPolicy,BaseState>::add_state<ContainingSM>::new_state_helper(boost::msm::dummy<__formal>) const' If I replace the ::boost::mpl by boost::mpl, it compiles fine. But I'm still wondering if I'm doing something wrong or the compiler. Does anyone have an answer? Thanks in advance, Christophe

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[Math] boost::math::signbit returns false for -NAN
by Hartmut Kaiser 11 Mar '09

11 Mar '09

Hi all, the boost::math::signbit function in trunk fails for an argument of -NAN. #include <boost/math/special_functions/sign.hpp> int main() { using boost::math::signbit; BOOST_ASSERT(signbit(-std::numeric_limits<double>::quiet_NaN())); return 0; } I'd expect to get a '1' back, but the function returns zero and the assertion fails. I know it worked while using Jon Rade's floating point utilities library from the vault. Does this have been integrated? Regards Hartmut

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[filesystem][cygwin] Standard conformance for wide characters
by Beman Dawes 11 Mar '09

11 Mar '09

I've decided not to attempt support for Cygwin in the next version of Boost.Filesystem. Cygwin's lack of library support for wchar_t is the problem . For the current Boost.Filesystem version (v2), the necessary workarounds are so pervasive that the implementation code is much harder to read and maintain. Witness the number of bug reports that are Cygwin specific. For v3, currently under development, trying to support Cygwin would be even harder, and would cause a serious delay in development. Plus I'm tired of waiting for the cygwin folks to come into full C++ conformance. IIUC, the reason Cygwin doesn't provide C++ standard library support for wchar_t is that the underlying C library is missing the C wchar_t functions. Perhaps Boosters who care about Cygwin could spearhead an effort to add the missing C support? The needed functionality isn't all that complex; the main problem might be just learning enough about how Cygwin/GCC is configured and built to be able to add a fairy small number of C functions. Thoughts? --Beman

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Question about futures library that was written by Anthony Williams
by Jon Shuler 11 Mar '09

11 Mar '09

There is an example in the documentation under Creating Asynchronous Values that shows how to call a function. Is it possible to call a member function that has arguments? Jon

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[1.39.0] New libraries?
by Beman Dawes 11 Mar '09

11 Mar '09

Are there any new libraries that will be ready to go into the 1.39.0 release? Thanks, --Beman

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[Review] RangeEx review extended to the 10th of March
by Thorsten Ottosen 11 Mar '09

11 Mar '09

Dear Developers and Users, The review period is extended one week. If you find this library interesting, please submit a review. The discussion so far may be found here: http://archives.free.net.ph/message/20090220.122836.73bdbd04.en.html Below you will find a description of the library and information on how to write a review. best regards Thorsten, review manager What is it? +++++++++++ The library provide two very useful extensions to the range library 1. Range-based algorithms. E.g. boost::sort( rng ); which is a convenient wrapper of instead of std::sort( boost::begin(rng), boost::end(rng) ); But the new interface also allows for more expressive code because (on the fly) composition of algorithms suddenly is possible. 2. Range adaptors. E.g. std::vector<int> vec = ...; boost::copy( vec | boost::adaptors::reversed, std::ostream_iterator<int>( std::cout ) ); where the expression "vec | boost::adaptors::reversed" wraps the iterators of the range on the left in reverse iterators. The library provides a wide range (no pun intended) of Range adaptors, and they are a powerful way to create ranges on the fly and pass them to algorithms. Getting the library +++++++++++++++++++ The library may be downloaded from http://www.cs.aau.dk/~nesotto/boost/range_ex.zip or from the Boost vault under "Algorithms". The docs may be browsed online here http://www.cs.aau.dk/~nesotto/boost/libs/range/ Please note that the documentation is integrated with the current Range ilbrary. Therefore the relevant sections for the review is http://www.cs.aau.dk/~nesotto/boost/libs/range/doc/adaptors.html and http://www.cs.aau.dk/~nesotto/boost/libs/range/doc/algorithms.html The code may be browsed here: http://www.cs.aau.dk/~nesotto/boost/boost/range/ Notice the library is header only (exception: the adaptor tokenized() depends on Boost.Regex). Writing a review ++++++++++++++++ If you feel this is an interesting library, then please submit your review to the developer list (preferably), or to the review manager. Here are some questions you might want to answer in your review: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick - reading? In-depth study? - Are you knowledgeable about the problem domain? And finally, every review should answer this question: - Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion. Special considerations ++++++++++++++++++++++ Various RangeEx like libraries have been implemented in the past. You might want to compare with those libraries when you form your oppinion: 1. John Torjo's range lib http://rangelib.synesis.com.au/libs/boost-rangelib-20040913.zip http://torjo.com/rangelib/index.html 2. Adobe's ASL libraries include range-based algorithms: http://stlab.adobe.com/group__algorithm.html I'm looking forward to your review. best regards Thorsten, Review Manager

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RangeEx review
by Mathias Gaunard 10 Mar '09

10 Mar '09

Here is a quick review of RangeEx. > - Do you think the library should be accepted as a Boost library? Yes, assuming issues raised in the recent discussions are addressed, and that people agree on the naming. > - What is your evaluation of the design? It is nice and pretty. Here are a few comments: - I am unsure about the syntax of the unified return type system. It's very practical, however, but not so pretty. - Fusion of the function syntax and pipe syntax for adaptors would be useful, so that both range | transformed(f) and transformed(range, f) may be written. - Relying on standard algorithms means that the functors have to provide a result_type. I would like the functors to be automatically wrapped so that boost::result_of can be used instead. I don't know if Boost.Iterator needs it too. - In the sandbox version, find(range) used to call range.find() if range had a find member (the has_find meta-function had a poor implementation, but that could have been solved). I don't know why this feature was removed, but I personally liked that better. - I would like to library to also provide lazy range generators, potentially defining an infinite range recursively. - Adaptors for type filtering within heterogeneous sequences (sequences of "potentially smart" pointers, sequences of variants, sequences of any...) would also be a plus. It's basically a filter+transform at the same time. I found such an adaptor primitive very practical when dealing with trees, for example. > - What is your evaluation of the implementation? It seems good. It's mostly just forwarding things to standard algorithms or Boost.Iterator for adaptors, nothing much to say. > - What is your evaluation of the documentation? Simple, but doesn't necessarily need to be more complicated. > - What is your evaluation of the potential usefulness of the library? Huge. I deal with sequences (or ranges) of objects everyday, and being able to express operations directly on them would make my code simpler and clearer. > - Did you try to use the library? With what compiler? Did you have any problems? I used an old version from the sandbox, with a few custom modifications, less than a year ago to code some experimental proof-of-concept C++ wrapper over a hierarchical thread scheduler written in C (a component which mapped trees of tasks to trees of processors) so as to see how it could make the code more high-level. This was done with GCC 4.2. I didn't have problems except making it work with a lambda DSEL (I actually cheated and used typeof for return type deduction everywhere at the time). > - How much effort did you put into your evaluation? A glance? A quick - reading? In-depth study? I only quickly read the documentation and gave a glance at the version under review; but I did study the sandbox version more in-depth. > - Are you knowledgeable about the problem domain? I know about ranges, iterators, functional programming, and lazy sequences fairly well.

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Help needed with some Math lib failures
by John Maddock 10 Mar '09

10 Mar '09

Folks, There are a few failures from Boost.Math (for example http://tinyurl.com/clvlq3) which I'm unable to reproduce locally - it seems only certain (possibly AMD x86-64 machines running Linux or *BSD) exhibit the problem. I can provide a test case to help with debugging what's going on, but I need to find someone who can reproduce the issue first. So... if you think you can help, then cd into libs/math/test and do a: bjam gcc test_hypergeometric_dist0 test_hypergeometric_dist1 test_hypergeometric_dist2 test_hypergeometric_dist3 test_hypergeometric_dist4 test_hypergeometric_dist5 and if one or more fail then let me know the failure message and I'll put together a test case. Many thanks in advance! John.

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Request for interest in the new Synchro library
by vicente.botet 10 Mar '09

10 Mar '09

Hi, I would like to know if the Boost community is interested in the Synchro library. Of course there is a lot of work to do, but I think that there is enough material to start a discussion on the approach. I'd appreciate it if people could take a look, test it on their compiler and give me some feedback. The library is available at Boost Sandbox: https://svn.boost.org/svn/boost/sandbox/synchro and Boost Vault: http://www.boostpro.com/vault/index.php?action=downloadfile&filename=synchr… that iIncludes every thing on the Sandbox + Html documentation Some examples use Boost.Interthreads also (available on the vault and the sandbox). This library is a compilation of what I have found in the literature not yet present in Boost. My main concern has been to boostify all these ideas in a coherent way. Next follows an overview of the library features: Boost.Synchro provides: * A uniform usage of Boost.Thread and Boost.Interprocess synchronization mechanisms based on lockables(mutexes) concepts and locker(guards) concepts. o lockables traits and lock generators, o lock adapters of the Boost.Thread and Boost.Interprocess lockable models, o locker adapters of the Boost.Thread and Boost.Interprocess lockers models, o complete them with the corresponding models for single-threaded programs: null_mutex and null_condition classes, o locking families, o semaphore, o condition_lockable lock which put together a lock and its associated conditions. * A coherent exception based timed lock approach, * A rich palette of lockers as o strict_locker, nested_strict_locker, o condition_locker, o reverse_locker, nested_reverse_locker, o locking_ptr, on_dereference_locking_ptr, o externally_locked, * A polymorphic lockable hierarchy. * High-level abstractions for handling more complicated synchronization problems, including o monitor for guaranteeing exclusive access to an object, and o a so-called rendezvous mechanism for handling direct communication between objects concurrent_components via ports using an accept-synchronize protocol based on the design of the concurrency library in the Beta language. On going work * array_locker and tuple_locker locker containers. * A complement to the already present in Boost.Thread lock, try_lock free functions: o lock_until, lock_for, try_lock_until, try_lock_for Best regrads, Vicente Juan Botet Escribá

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