December 2010 - Boost-users

[netlib] Update: 0.9 will not be header-only
by Dean Michael Berris 03 Dec '10

03 Dec '10

Hi Everyone, To those who are following the development of cpp-netlib (which shall be submitted for review /soon/ as Boost.Netlib), the current state of 0.9-devel and thus what's going to come out officially as 0.9 in a couple of weeks, will not be header-only. Aside from the obvious reason that the compile-times are starting to become unbearable (>10 minutes to build the whole test suite!!) and after noticing that the intended simplicity of the API with tag-metafunction dispatch is limiting the expressiveness of the HTTP client types, the 0.9 release will be the first release that will require an externally linked-in static library. The biggest culprit at the moment has been the implementation of the URI parser that uses Boost.Spirit Qi and >10 rules in the URI parsing grammar. The URI implementation is really declarative and nicely written (thanks go out to Jeroen Habraken for making that happen). The down-side of this has been the compile times: building the simple HTTP client takes close to one minute on the machine I'm using -- and by moving it to an externally-linked static lib, the compile of the same HTTP client is cut down to 10 seconds. Before you ask if I'm using GCC, the answer is no, I'm using Clang when developing so that I get as much speed as I can when doing the edit-rebuild-test cycle. I've written about what I've been doing and what I'll be doing in my three recent articles at C++ Soup. If you want to get more details, please follow the links below. http://cplusplus-soup.com/2010/12/03/cpp-netlib-moving-away-from-header-onl… http://cplusplus-soup.com/2010/12/02/cpp-netlib-demolition-day/ http://cplusplus-soup.com/2010/12/01/cpp-netlib-reducing-compilation-times/ Have a great weekend everyone, please send your qestions/comments/suggestions over either directly to me or through the various mailing lists (Boost-devel, Boost-users, cpp-netlib-devel). -- Dean Michael Berris deanberris.com

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NewBie: help needed generating documentation with quickbook and bjam
by Wilhelm 03 Dec '10

03 Dec '10

Hello, this is a absolute newbie question: I try to write some documentation using quickbook. I was able to generate a .xml file. But now I have no idea how to produce a html or pdf version thereof. I read some documentation about bjam and installed the neccessary libraries (I hope). But I didn't find any documentation about how to write a .jam file for this purpose. Can someone help solving this (dumb) question? -- Wilhelm

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boost/parameter/keyword.hpp warning, TI compiler
by Krzysztof Czainski 03 Dec '10

03 Dec '10

Hello, When I compile a file, that consists of only one line: #include <boost/parameter/keyword.hpp> with a Texas Intstruments compiler for DSP (cgtools-6.1.12); boost-1.45.0, I get this warning: boost/parameter/aux_/void.hpp, line 20: warning #1369-D: static local variables of extern inline function are not resolved to single copy. Not ANSI C++ Compliant It referes to: inline void_& void_reference() { static void_ instance; return instance; } In this particular context this warning seams harmless, so I would like to suppress it. As far as I know, this compiler doesn't have a #pragma warning(disable:1369) equivalent... I know how suppress this kind of warning globally, but I would not like that, because in other contexts this is an important warning. Any ideas, how I could suppress this warning locally, in code perhaps? Cheers Kris

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[Units] unary minus on units is counter intuitive (or a bug)
by alfC 03 Dec '10

03 Dec '10

Hi, I found this counterintuitive result of applying the unary minus operator to a unit "- si::meter" is the same as "si::meter" (or any other unit). or worst std::cout << - si::meter*1. << std::endl; // prints 1*m i.e. the minus is explicitly ignored. The root of the problem is this curious line in boost/units/unit.hpp /// unit runtime unary minus template<class Dim,class System> typename unary_minus_typeof_helper< unit<Dim,System> >::type operator-(const unit<Dim,System>&) { typedef typename unary_minus_typeof_helper< unit<Dim,System> >::type type; return type(); } a more intuitive result (but not completely elegant) could be attained by defining instead: template<class Dimension, class System> quantity<unit<Dim, System> > operator-(unit<Dim, System> const& u){ return -1.*u; } This is a definition that I could add BUT it will conflict with the original definition. Another way, could be to specialize unary_minus_typeof_helper<...>::type to be something that is not a unit but holds the negative "direction" and the cast to Type(-1)*unit quantity but it seems overly complicated for the purpose. Note aside: Why would I need "minus units" in the first place? The original code that produced the confusion was - kB*T which appears commonly in physics. kB is the "atomic" unit of entropy/ specific heat (atomic::heat_capacity) and T is a temperature quantity. This was parsed as (-kB)*T and then as kB*T i.e. the minus sign was ignored all together. In my opinion unary operator- should not be defined for units in the first place. The current definition only makes things worst, by creating a counter intuitive result AND making the fix conflict with the definition. Thoughts? Thank you, Alfredo

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mpi all_reduce
by Kraus Philipp 03 Dec '10

03 Dec '10

Hello, how can I use the mpi::all_reduce with std::accumulate? I would reduce the values of each process with a sum function Thanks Phil

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boost-1.45.0 / MSVC 9.0: bjam --layout=system fails
by Roman Neuhauser 03 Dec '10

03 Dec '10

hello, i'm trying to build 1.45.0 on Windows 7 with MSVC 9.0. I'm using the Windows SDK shell. "bootstrap; bjam" passes. "bootstrap; bjam --layout=system" fails: c:/MinGW/msys/1.0/home/roman/wc/boost_1_45_0/tools/build/v2/build\virtual-target.jam:1066: in virtual-target.register-actual-name from module virtual-target error: Duplicate name of actual target: <pstage\lib>libboost_date_time.lib error: previous virtual target { common%common.copy-libboost_date_time.lib.STATIC_LIB { msvc%msvc.archive-libboost_date_time.lib.STATIC_LIB { msvc%msvc.compile.c++-gregorian\greg_month.obj.OBJ { gregorian/greg_month.cpp.CPP } } { msvc%msvc.compile.c++-gregorian\greg_weekday.obj.OBJ { gregorian/greg_weekday.cpp.CPP } } { msvc%msvc.compile.c++-gregorian\date_generators.obj.OBJ { gregorian/date_generators.cpp.CPP } } } } error: created from ./stage-proper error: another virtual target { common%common.copy-libboost_date_time.lib.STATIC_LIB { msvc%msvc.archive-libboost_date_time.lib.STATIC_LIB { msvc%msvc.compile.c++-gregorian\greg_month.obj.OBJ { gregorian/greg_month.cpp.CPP } } { msvc%msvc.compile.c++-gregorian\greg_weekday.obj.OBJ { gregorian/greg_weekday.cpp.CPP } } { msvc%msvc.compile.c++-gregorian\date_generators.obj.OBJ { gregorian/date_generators.cpp.CPP } } } } error: created from ./stage-proper error: added properties: <debug-symbols>off <define>NDEBUG <inlining>full <optimization>speed <runtime-debugging>off <variant>release error: removed properties: <debug-symbols>on <inlining>off <optimization>off <runtime-debugging>on <variant>debug c:/MinGW/msys/1.0/home/roman/wc/boost_1_45_0/tools/build/v2/build\virtual-target.jam:490: in actualize-no-scanner from module object(file-target)@3863 c:/MinGW/msys/1.0/home/roman/wc/boost_1_45_0/tools/build/v2/build\virtual-target.jam:135: in object(file-target)(a)3863.actualize from module object(file-target)@3863 c:/MinGW/msys/1.0/home/roman/wc/boost_1_45_0/tools/build/v2\build-system.jam:748: in load from module build-system c:\MinGW\msys\1.0\home\roman\wc\boost_1_45_0\tools\build\v2/kernel\modules.jam:283: in import from module modules c:\MinGW\msys\1.0\home\roman\wc\boost_1_45_0\tools\build\v2\kernel\bootstrap.jam:142: in boost-build from module c:\MinGW\msys\1.0\home\roman\wc\boost_1_45_0\boost-build.jam:17: in module scopefrom module i need the system layout build. how can i get around the error? -- roman

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Nested If in boost:mpl::if_
by Leon Sit 02 Dec '10

02 Dec '10

hi all I am trying to use mpl to do some simple type computation that involves nest if statements The logic is somewhat like if(T is Libor) return LiborType if( or( or(T = Euribor, T = EURLibor), is_base_of(T, Libor) ), ConstrType2, if( or(is_base_of(T, Euribor), is_base_of(T, EURLibor)), ConstrType1, ConstrType ) ) When I first coded it and instantiate T with some derived class of Libor, the final type is always a generic type. Few more testing shows that the inner if_ in the code below typedef typename boost::mpl::if_ < boost::is_same<InType, QuantLib::Libor>, QuantLib::Libor, boost::mpl::if_ < boost::mpl::or_ < boost::is_same<InType, QuantLib::Euribor>, boost::is_same<InType, QuantLib::EURLibor>, boost::is_base_of<QuantLib::Libor, InType> > ConstrType2, boost::mpl::if_ < boost::mpl::or_ < boost::is_base_of<QuantLib::Euribor, InType>, boost::is_base_of<QuantLib::EURLibor, InType> >, ConstrType1, ConstrType > > >::type Type; does not reduce to ConstrType1/ConstrType2/ConstrType but the whole is used as a type. So the final Type is just a type with 3 nested if_ class inside. I tried linearising the logic but this introduces other problem. Is this a bug or a limitation of mpl::if_? Thanks

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[Boost.Test] does not always include checkpoint information
by Peter Soetens 02 Dec '10

02 Dec '10

I'm using boost 1.40. When parsing the output of a Boost.Test xml file, I sometimes get this error: "test-result.xml:cvc-complex-type.2.4.b: The content of element 'Exception' is not complete. One of '{LastCheckpoint}' is expected." (output from Hudson Test plugin). It appears that It does not consider the entry point of the unit test function as a checkpoint, while the documentation says it does. I can 'fix' this by inserting check/pass points at the beginning of every function, but shouldn't Boost.Test do this automatically ? Peter

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mpi non-blocking communication
by Kraus Philipp 02 Dec '10

02 Dec '10

Hello, I have some problems with the MPI non-blocking communication, but I can be a thinking error. The CPU 0 (rank 0) creates a loop with this: while (true) { std::string l_str; p_com.irecv( mpi::any_source, LOGGER_MPI_TAG, l_str ); } p_com is the commuicator object. All other CPUs (!= 0) can send a message to CPU 0, which should be received. The CPUs (!=0) can send a message, but they need not, so I would create this with non-blocking communication. At this time my l_str is alway empty, so it seems that the message, that are send, not transmittet, received or not inserted into l_str. I hope the problems is described in a clear way. I would like that the CPU 0 can receive message of there are some and all other CPUs can send messages. Thanks Phil

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Writing an inline nullary function object?
by Robert Jones 02 Dec '10

02 Dec '10

How can I write an inline nullary function object, returning a fixed value? The equivalent of this... int x = 4; int f( ) { return x; } boost::function<int()> g = f; but without defining the intermediate f()? I thought this might work... boost::function<int()> g = bind(bind(apply<int>(), _1 ), x ); but maybe I've not got it quite right? Thx - Rob.

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