- Boost - lists.boost.org

[mpl-cf] [RFC] MPL Real Numbers using Continued Fractions
by Hal Finkel 01 Dec '10

01 Dec '10

Hello, A few months ago, I created an MPL extension type for representing real numbers. The indented use is for compile-time generation of floating-point constants, although it could also be used for MPL-based graph algorithms, etc. The primary design requirement was that almost any compiler would be able to completely inline the conversion to floating-point (which means no functional recursion can be used), and I think I've achieved that. The current implementation uses a modified version of MPL's vector type (modified to add the conversion to floating point, add "overloads", and to remove the typeof-based implementation variant (which is incompatible with the floating-point conversion)). I've posted the code to the Boost vault under the "Template Metaprogramming" section; the file name is boost-mpl-cf-20100531.zip Continued fractions were chosen for the representation because the associated algorithms are simple, and simple proved important for keeping down compilation times. Even so, the compilation times might be too long for practical use. You can decrease the compilation time by using a shorter maximum cf-length by defining BOOST_MPL_LIMIT_CF_SIZE to be 10 instead of 20. The current default is 20 to allow an effective precision near that of a double. Also, continued fractions, being "based on" rational numbers, can exactly represent any rational (for example, 1/3) so the computations can be more accurate than those using a floating-point representation. If you don't know what a continued fraction is, and would like to know, you can check out the wikipedia page: http://en.wikipedia.org/wiki/Continued_fraction The current implementation supports addition, subtraction, multiplication and division, comparison ops, some constants like pi, and I've included sin()/cos() as well. I've not yet written any real documentation, but the archive has a couple of test programs; the usage is pretty simple. Each test program has many individual tests, so its compilation time will be representative of a more-complicated computation, if you just need to do a few things, it would be much faster. If there is interest, I'll add support for generating numbers using metafunctions, write some documentation, jam files, etc. Let me know what you think, and I welcome suggestions, criticisms, etc. Also, I've currently tested using only the GNU and Intel compilers, so let me know whether it does or does not work when using something else. Thanks again, Hal P.S. I know that there is a mpl_math archive on the vault from back in 2007. I did not discover this until after I had almost finished writing my mpl-cf implementation, but, the mailing-list messages from the time indicate that it was too slow to be used practically, since I think the continued fractions algorithms are simpler, mpl-cf might be better, but I've not tested it to find out.

6 11

[Bug Sprint] Status for Wednesday, December 1st
by Marshall Clow 01 Dec '10

01 Dec '10

There were 30 changes to the trac database yesterday. [ I'd like to say "30 tickets were changed", but some tickets were changed more than once. ] That's a notable decrease in activity from the last few days. In the last bug sprint, we closed almost 100 tickets. So far this time, we've closed 17. If you think it's too late to get involved - you're wrong! A couple of notes: 1) Please log into the Trac system before you add/modify a ticket. "Anonymous said:" is hard to follow up. 2) It is perfectly OK to add a comment to a ticket that says "I tested this patch on my system (foo, gcc 1.2.3.4, etc) and it worked fine/didn't work/etc" General information about the bug sprint is here: https://svn.boost.org/trac/boost/wiki/BugSprintNov2010 General information about how the Trac system works is here: https://svn.boost.org/trac/boost/wiki/TicketWorkflow Overall bug count: November 26: 946 November 27: 939 November 28: 930 November 29: 934 (whoops, that's the wrong direction!) November 30: 931 (better, but the delta is too small) December 1: 929 Activities on the trac system yesterday: avibahra@ 3 marshall 3 hkaiser 3 jwellico 3 --others-- 18 Useful reports: https://svn.boost.org/trac/boost/report/1 -- full list of tickets https://svn.boost.org/trac/boost/report/18 -- ticket counts by owner https://svn.boost.org/trac/boost/report/19 -- ticket counts by component https://svn.boost.org/trac/boost/report/20 -- ticket counts by ticket type https://svn.boost.org/trac/boost/report/21 -- ticket counts by milestone

1 0

Conversion operator for boost any
by Leonid Frenkel 01 Dec '10

01 Dec '10

Hello, I found adding the following conversion operator to Boost.Any was very helpful in some cases: (specially when using macros inside functions) template <typename ValueType> operator ValueType() { return any_cast<ValueType>(*this); }

1 0

Re: [boost] Boost 1.45 compile error
by Eric Niebler 01 Dec '10

01 Dec '10

(bringing in boost dev...) This sounds bad. Can anybody confirm? -- Eric Niebler BoostPro Computing http://www.boostpro.com On 11/19/2010 4:35 PM, gast128 wrote: > Hello all, > > just tried out Boost 1.45 on VStudio 2003 but I got a compile error by only > including type_traits: > > #include <boost/type_traits.hpp> > > int main() > { > return 0; > } > > C:\Work Sdk\boost_1_45_0\boost\typeof\msvc\typeof_impl.hpp(160) : error C2027: > use of undefined type '<Unknown>' > C:\Work Sdk\boost_1_45_0\boost\typeof\msvc\typeof_impl.hpp(143) : see > declaration of '<Unknown>' > C:\Work Sdk\boost_1_45_0\boost\typeof\msvc\typeof_impl.hpp(160) : see > reference to class template instantiation '<Unknown>' being compiled > C:\Work Sdk\boost_1_45_0\boost\type_traits\common_type.hpp(121) : see > reference to class template instantiation '<Unknown>' being compiled > C:\Work Sdk\boost_1_45_0\boost\type_traits\common_type.hpp(123) : see > reference to class template > instantiation 'boost::type_traits_detail::common_type_2<T,U>' being compiled > C:\Work Sdk\boost_1_45_0\boost\typeof\msvc\typeof_impl.hpp(160) : error C2146: > syntax error : missing ';' before identifier 'wrapped_type' > C:\Work Sdk\boost_1_45_0\boost\typeof\msvc\typeof_impl.hpp(160) : error > C2501: '<Unknown>' : missing storage-class or type specifiers > C:\Work Sdk\boost_1_45_0\boost\typeof\msvc\typeof_impl.hpp(161) : error > C2653: 'wrapped_type' : is not a class or namespace name > > afaik it seems located on 121 in 'boost/type_traits/coomon_type.hpp' > > Anyone can help?

12 27

[gil] New IO release
by Christian Henning 30 Nov '10

30 Nov '10

Hi there, a new gil IO extension is ready for download. Here is the link: http://code.google.com/p/gil-contributions/downloads/detail?name=boost_revi… This is the final version that will be used for the boost review. Could someone try to build documentation on Linux? Thanks to all people that have helped me out. Regards, Christian

5 18

Sandbox cleanup
by Vladimir Prus 30 Nov '10

30 Nov '10

Folks, it appears that at present, our SVN sandbox is in fairly confused state. A fresh checkout contains objects of very different kinds, in particular: - 'boost' directory, that has assorted headers supposedly meant for future. - 'libs' directory, with various libraries - Pile of top-level directories for libraries-in-development, each containing 'boost' and 'libs' subfolders. - Subdirectory SCons, with a copy of entire Boost tree, buildable with scons. - Subdirectory 'win32-doc-tools', which surely does not contain a library - Some directories named after specific people. It's not clear whether those directories contain a single future library, or several, or what. It seems that a straight-forward approach to fix that is to have two separate areas in sandbox, as follows: [using fixed font to read the below might work better] /sandbox /libraries /proposed-lib1 /boost /libs .... /branches /jrhacker-assorted-fixes [complete branch of trunk, with changes] /SCons [complete branch of trunk, with SConstruct, etc] Comments? -- Vladimir Prus http://vladimir_prus.blogspot.com Boost.Build: http://boost.org/boost-build2

8 9

[Bug Sprint] Status for Tuesday, November 30th
by Marshall Clow 30 Nov '10

30 Nov '10

There were 59 changes to the trac database yesterday. [ I'd like to say "59 tickets were changed", but some tickets were changed more than once. ] A couple of notes: 1) Please log into the Trac system before you add/modify a ticket. "Anonymous said:" is hard to follow up. 2) It is perfectly OK to add a comment to a ticket that says "I tested this patch on my system (foo, gcc 1.2.3.4, etc) and it worked fine/didn't work/etc" General information about the bug sprint is here: https://svn.boost.org/trac/boost/wiki/BugSprintNov2010 General information about how the Trac system works is here: https://svn.boost.org/trac/boost/wiki/TicketWorkflow Overall bug count: November 26: 946 November 27: 939 November 28: 930 November 29: 934 (whoops, that's the wrong direction!) November 30: 931 (better, but the delta is too small) If you want to contribute, I would suggest looking at the old tickets, and seeing what you can do with them: Here are the tickets by milestone: Milestone Tickets To Be Determined 362 Boost 1.43.0 100 Boost 1.44.0 94 Boost 1.42.0 74 Boost 1.36.0 48 <https://svn.boost.org/trac/boost/query?status=assigned&status=new&status=re…> Boost 1.40.0 48 Boost 1.39.0 43 <https://svn.boost.org/trac/boost/query?status=assigned&status=new&status=re…> Boost 1.41.0 39 <blank> 36 Boost 1.38.0 30 <https://svn.boost.org/trac/boost/query?status=assigned&status=new&status=re…> Boost 1.37.0 25 <https://svn.boost.org/trac/boost/query?status=assigned&status=new&status=re…> Boost 1.45.0 13 Boost 1.46.0 12 Website 1.X 4 Boost 1.47.0 1 Boost.Jam 3.1.18 1 Boost.Jam 4.0.0 1 Activities on the trac system yesterday: viboes 16 anonymous 12 ramey 7 mikhailberis 3 marshall 3 --others-- 18 Useful reports: https://svn.boost.org/trac/boost/report/1 -- full list of tickets https://svn.boost.org/trac/boost/report/18 -- ticket counts by owner https://svn.boost.org/trac/boost/report/19 -- ticket counts by component https://svn.boost.org/trac/boost/report/20 -- ticket counts by ticket type https://svn.boost.org/trac/boost/report/21 -- ticket counts by milestone

3 2

virtual protected inheritance and default constructors
by gzp 30 Nov '10

30 Nov '10

Hello, This might be an off-topic question, but there must be here some clever guy who can answer my question. class Impl { public: Impl() { std::cout << "j"; } // want to eliminate, but cannot :( Impl(int j) { i = j; std::cout << "i"; } int i; }; template<typename TImpl> class A : virtual protected TImpl { public: void geti() const { std::cout << "gi" << i << "\n"; } }; template<typename TImpl> class B : public A<TImpl> { public: void seti(int a) { this->i = a; } }; class CA : public A<Impl> { public: CA() : Impl(3) { std::cout << "ca " << i;} }; class CB : public B<Impl> { public: CB() : Impl(2) { std::cout << "cb " << i;} }; //abuse of interfaces template<typename TImpl> void foo( A<TImpl>& p_a ) { p_a.geti(); } template<typename TImpl> void foo( B<TImpl>& p_a ) { p_a.seti( 2 ); } template<typename TImpl> void foo2( A<TImpl>& p_a ) { p_a.geti(); } int main( int, char*[] ) { CA a; std::cout << "\n"; CB b; std::cout << "\n"; foo(a); foo(b); foo2(a); foo2(b); return 0; } The basic concept was that: there is a simple implementation class and using some interfaces (bridge classes) the appropriate function call (foo) can be ensured using compile time type checking. The implementation might provide implementation to multiple interfaces (bridge classes) and these interfaces guarantee the required operation for each (template)functions. The role of A and B is to provide the interface and bridge it to the implementation. The only missing part was, how to construct a CA and CB object. They might have completely different construction parameters and the virtual protected inheritance partially solved the problem. BUT the default constructor is always required (VC2008) even tough it gets never called (I don't want to create any object from A,B (who are missing these default ctors) but I couldn't tell it to the compiler) "The declare and don't define" doesn't solve the problem either as the linker requires the default Impl ctor even though it never gets called. For example: impl1: a range iterator for an 1D array: ctor requires the array.begin, array.end impl2 a random generator range: ctor requires the random seed CA: isEmpty, front, popFront CB: put, mutable front copy from random range to array is valid (template foo(A,B)), but not the other way (no template foo(B,A)) Thanks, Gzp -- View this message in context: http://boost.2283326.n4.nabble.com/virtual-protected-inheritance-and-defaul… Sent from the Boost - Dev mailing list archive at Nabble.com.

1 0

[1.45][filesystem3] utf8 support
by Jochen Wilhelmy 30 Nov '10

30 Nov '10

Hi! now I switched to filesystem3. Everything works, but there is one issue on windows. I'd like to use utf8 in my application. I can imbue an utf8-locale to path. But if I have legacy libraries that take only 8 bit strings then I would pass utf8 instead of ansi (e.g. latin1). Therefore filesystem::path can be seen as a gateway between the application and the operating system and therefore needs two locales, one for the application and one for the operating system. Or an additional method utf8() that returns utf8 regardless of the locale. What do you think? -Jochen

2 1

[thread] On shared_mutex
by Howard Hinnant 30 Nov '10

30 Nov '10

Three years ago I wrote N2406 "Mutex, Lock, Condition Variable Rationale" (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2406.html) for the C++ committee in an attempt to explain the combined proposed std::mutex/std::unique_lock package and how it fit together with the tr2-targeted shared_mutex/shared_lock package. This paper also proposed an upgrade_mutex and upgrade_lock. Since that time, the std-proposed stuff has been accepted with some name changes, and a reworking of the timed-locking interface. Additionally Anthony Williams has implemented much of the shared-locking functionality in boost (and done a very nice job with it). That being said, I disagree with some fairly major design changes between N2406 and what is now in the boost library. Four of the major changes are: 1. upgrade_mutex has been dropped. 2. Some, but not all of the functionality in upgrade_mutex has been moved into shared_mutex. 3. Some of the upgrade_mutex functionality is missing completely. The missing functionality is summarized in the "Ownership Modes" charts in the form of red arrows. 4. boost allows implicit conversions between the lock types. N2406 made these conversions explicit. Rationale: changing the ownership mode of a mutex is something that should be well documented in the code. I have an updated implementation of <shared_mutex> (under the boost license) here: http://home.roadrunner.com/~hinnant/mutexes/shared_mutex http://home.roadrunner.com/~hinnant/mutexes/shared_mutex.cpp There is a tutorial-style description of this library here: http://home.roadrunner.com/~hinnant/mutexes/locking.html The tutorial includes a brief description of the use of most of the components, complete synopses, and an examples section. It also notes where this design differs from the boost design and explains why I believe the boost design is in error. Comments appreciated, and all are welcome to use this code under the boost license. I will likely update this document in response to comments and its date at the top will correctly reflect the last time it was updated. This library, or a variation of it, will probably be submitted to TR2, and so getting feedback on the differences between this and the boost implementation is important. Thanks, Howard

5 17