March 2013 - Boost - lists.preview.boost.org

required toolsets
by Steven Watanabe 15 May '14

15 May '14

AMDG The list of required toolsets in explicit-failures-markup.xml is out-dated. Therefore, if no one objects, I propose setting it to the following: msvc-10.0, msvc-11.0, gcc-4.6, gcc-4.7, clang-darwin-11, clang-darwin-4.2.1, clang-linux-3.1, clang-linux-3.2, gcc-mingw-4.7, gcc-mingw-4.6 (two releases of each major compiler that appears in both the trunk and release regression tests) The sole effect of this is to determine which toolsets appear in the issues list: http://www.boost.org/development/tests/trunk/developer/issues.html In Christ, Steven Watanabe

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safe bool not safe enough ?
by John Maddock 28 Jul '13

28 Jul '13

Just discovered (oops!) that the so called safe bool ideom is not as safe as it appears, for example: class Testable { bool ok_; typedef void (Testable::*bool_type)() const; void this_type_does_not_support_comparisons() const {} public: explicit Testable(bool b=true):ok_(b) {} operator bool_type() const { return ok_==true ? &Testable::this_type_does_not_support_comparisons : 0; } }; Testable t(true); bool b = t; // Compiles OK - Ooops! Which is causing multiprecision to misbehave when used in conjunction with uBlas: https://svn.boost.org/trac/boost/ticket/8292#comment:2 I guess making the conversion explicit in C++11 mode would help (I still need to test that), but is there a C++03 solution? Thanks, John.

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[gil] Ok to merge new gil's extension to release branch?
by Christian Henning 19 May '13

19 May '13

Hi, is it ok? The merge would include io, toolbox, numerics and some other changes to gil's code itself. Regards, Christian

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[bootstrap/1.53] jam0.exe crashes when bootstrapping for VC2012 AMD64
by rjeczalik 11 May '13

11 May '13

Hi, I'm trying to build Boost 1.53 using VC2012 amd64 (toolset=msvc-11.0 address-model=64) and Windows Server 2012 Standard. Bootstrapping fails with jam0.exe crash - some crash info: Crash stacktrace: ntdll.dll!000007f9bc781069() KernelBase.dll!000007f9b978764e() KernelBase.dll!000007f9b97d3658() jam0.exe!_findnext64i32(__int64 hFile, _finddata64i32_t * pfd) Line 165 jam0.exe!file_dirscan(_object * dir, void (void *, _object *, int, __int64) * func, void * closure) Line 180 jam0.exe!builtin_glob(frame * frame, int flags) Line 718 jam0.exe!function_run(_function * function_, frame * frame, _stack * s) Line 3390 jam0.exe!evaluate_rule(_object * rulename, frame * frame) Line 264 jam0.exe!function_call_rule(_jam_function * function, frame * frame, _stack * s, int n_args, const char * unexpanded, _object * file, int line) Line 468 jam0.exe!function_run(_function * function_, frame * frame, _stack * s) Line 3950 jam0.exe!parse_file(_object * f, frame * frame) Line 57 jam0.exe!main(int argc, char * * argv, char * * arg_environ) Line 488 jam0.exe!__tmainCRTStartup() Line 241 jam0.exe!mainCRTStartup() Line 164 kernel32.dll!000007f9b9de167e() ntdll.dll!000007f9bc7a3501() Line where it crashed was: if (!FindNextFile((HANDLE)hFile, &wfd)) { I've tried to watch the values of arguments passes to FindNextFile() - hFile looked like proper handle, however wfd.cFileName and wfd.cAlternateFileName contained garbage. Is this a known issue for 1.53? I've compiled version 1.52 using the same environment and the same configuration and everything went ok, I did not manage to reproduce the crash. It looks like only version 1.53 is affected. Regards, Rafael Jeczalik

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Specific-Width Floating-Point Typedefs
by Paul A. Bristow 04 May '13

04 May '13

There has recently been some discussion on improving portability of programs using floating-point. Drawing on the benefits from definition of typedefs for int32_t, int64_t, int128_t . we have drawn up a proposal to add similar typedefs for floating-point. Our draft document (in both html and pdf) is at https://svn.boost.org/svn/boost/sandbox/precision/libs/precision/doc/html/i… https://svn.boost.org/svn/boost/sandbox/precision/libs/precision/doc/precis… We hope to propose this to the SG6 Numerics subgroup of WG21 ISO C++ standards body. But would welcome comments from Boosters to help us improve this proposal. Thank you. Paul --- Paul A. Bristow, Prizet Farmhouse, Kendal LA8 8AB UK +44 1539 561830 07714330204 pbristow(a)hetp.u-net.com

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Voronoi benchmark update
by Sebastien Loriot 03 May '13

03 May '13

Hello, I'm involved in the CGAL Project, and saw the Voronoi benchmark. It would be nice if you could change the CGAL code slightly, as it is not as bad as it currently seems. Attached is the diff to the trunk of boost. Concerning the Voronoi diagram of points, a CGAL user, would use the Delaunay_triangulation_2 class. Concerning the Voronoi diagram of segments (that do not intersect) one would make a better choice for number types and traits classes. Also one better first inserts the endpoints and then the segments (I agree, this should definitely go into a member function). Admittedly our examples could be better. Cheers, Sebastien

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[log] Permission to merge to trunk
by Andrey Semashev 20 Apr '13

20 Apr '13

Hi, I'd like to ask for permission to merge Boost.Log v2 to Boost trunk. The library has passed the review back in 2010 and was provisionally accepted [1]. It has been reworked since then, and in a few recent posts I described the changes [2][3]. [1] http://lists.boost.org/boost-announce/2010/03/0256.php [2] http://thread.gmane.org/gmane.comp.lib.boost.devel/237748 [3] http://thread.gmane.org/gmane.comp.lib.boost.devel/239313

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GSoC 2013 - Boost registration?
by Paul A. Bristow 09 Apr '13

09 Apr '13

http://www.google-melange.com/gsoc/events/google/gsoc2013 March 18: 19:00 UTC Mentoring organizations can begin submitting applications to Google. March 29: 19:00 UTC Mentoring organization application deadline. Just checking that Boost has/is registering? Paul --- Paul A. Bristow, Prizet Farmhouse, Kendal LA8 8AB UK +44 1539 561830 07714330204 pbristow(a)hetp.u-net.com

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generate algorithm
by Fabian Bösch 02 Apr '13

02 Apr '13

Dear Boost community I am developing a library which extends the STL generate algorithm. It's aim is to improve performance for highly optimized (e.g. vectorized) generation mechanisms while it retains the same interface. This is especially useful when dealing with random number generation as there are several libraries (e.g. Intel MKL or AMD ACML) which provide means to generate a block of random values at once. However, the current STL generate algorithm is not able to cope with such "range generation". Is there any interest in a such a library for Boost? Cheers, Fabian Bösch

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traits classes vs. metafunctions
by Stefan Strasser 01 Apr '13

01 Apr '13

Hi everyone, are there any guidelines for boost libraries on when to use traits classes and when to use a metafunction for each member of a would-be traits class? I've seen both in boost libraries. c++11 uses traits classes (iterator_traits, pointer traits, ...), but Abrahams and Gurtovoy [1] argue that traits classes ("traits blobs") should be avoided "at all costs" because they are an unnecessary concatenation of multiple metafunctions into one metafunction with multiple return values. in practice, this means that if a single 'traits class member' aka 'metafunction result' ought to differ from the defaults, the entire traits class has to be reimplemented by the user, not only the metafunction whose result ought to differ from the default. on the other hand, asking a user to implement 5 or more metafunctions is much more tedious than implementing a traits class. possibility 1) template<...> struct property1 : mpl::bool_<...>{}; template<...> struct property2 : mpl::bool_<...>{}; template<...> struct property3 : mpl::bool_<...>{}; 2) template<...> struct ..._traits{ typedef mpl::bool_<...> property1; typedef mpl::bool_<...> property2; typedef mpl::bool_<...> property3; }; you could provide both, but in which "direction"? does a traits class refer to metafunctions, or do metafunctions refer to a traits class? a) template<...> struct ..._traits{ typedef typename property1<...>::type property1; typedef typename property2<...>::type property2; typedef typename property3<...>::type property3; }; b) template<...> struct property1 : ..._traits<...>::property1{} template<...> struct property2 : ..._traits<...>::property2{} template<...> struct property3 : ..._traits<...>::property3{} which is accessed when "calling" the metafunction? it seems to me that metafunctions are better for the "caller" and traits classes are better for the implementor of the traits/metafunctions. in my case, the caller is a library and the implementor is the user, so you might choose a traits class over metafunctions. but what if a new member is added that wasn't there before (like "property4"). the implementor of an (old) traits class could not have known about the new member, so accessing the new member (by the library) will result in an error, while a new metafunction "property4" could simply return a default. should new properties of traits classes only be accessed after making sure they exist, using SFINAE? there isn't a precedent for this in c++11. only new traits classes were introduced, but no new members of already existing traits classes. should metafunctions always be preferred? why did c++11 choose traits classes over metafunctions, even though the concept of a metafunction was introduced in c++11 (<type_traits>). Thanks [1] Abrahams; Gurtovoy: C++ Template Metaprogramming, 2.2 Metafunctions

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