- Boost-users - lists.boost.org

Null Stream
by Kraus Philipp 12 Jun '10

12 Jun '10

Hi, I'm new at boost, but I don't know how to use the http://beta.boost.org/doc/libs/1_43_0/boost/iostreams/device/null.hpp device. I must use the boost::iostreams::copy to copy a stream to the /dev/ null, but I don't know to declare my out null-output stream. Can anyone help me to declare the stream? Thanks Phil

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Re: [Boost-users] concat files for compression
by Brian Wood 12 Jun '10

12 Jun '10

Kraus Philipp: > On 2010-06-11 09:34:27 +0200, Roland Bock said: >> >> Hi, >> >> I see two options: >> >> a) You write a new multi_file_source class which can any number of input >> files. >> >> b) Instead of working with a source, you could work with a sink at the >> other end of the pipeline. Then just copy the content of the two files >> into the stream. > > Hi, > > I think I would like to use the second idea, but how I can do this? > I have some classes -- SendCompressedBuffer and ReceiveCompressedBuffer -- that may be helpful. SendCompressedBuffer uses bzip to compress data before it forwards the data. It is able to marshall files and other data. There's an archive -- fear not, it's all of 17,517 bytes -- that you can download and has the classes I mentioned. Brian Wood Ebenezer Enterprises http://webEbenezer.net (651) 251-9384 "The kingdom of heaven is like a treasure hidden in the field, which a man found and hid again; and from joy over it he goes and sells all that he has and buys that field."

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mpi reduce on a vector
by Prevrhal, Sven 12 Jun '10

12 Jun '10

I have a std::vector in each process and would like to sum them up by element in a master process such that v_master[0] = v_worker1[0] + v_worker2[0] +... v_master[1] = v_worker1[1] + v_worker2[1] +... ... boost::mpi::reduce(world, v_worker, v_master, std::plus<int>(), masterID) doesn't cut it because std::add only works for individual vector elements but not for a whole vector. So I could define my own functor struct vplus : public std::binary_function<std::vector<int>, std::vector<int>, std::vector<int>> { // functor for operator+ std::vector<int> operator()(const std::vector<int>& _Left, const std::vector<int>& _Right) const { // apply operator+ to operands std::vector<int> v(_Left.size()); std::transform(_Left.begin(), _Left.end(), _Right.begin(), v.begin(), std::plus<int>()); return (v); } }; and apply it like so in the distributor boost::mpi::reduce(world, a, b, vplus(), 0); This works, but here is my question: the functor makes a new vector v that gets returned and (do I say this right?) passed on to boost::mpi::reduce and goes out of scope. This making of a new vector strikes me as superfluous and wasteful (think big vectors) - should I avoid it, and if so, how? Cheers,Sven working on CUDA+Thrust+MPI for medical image processing The information contained in this message may be confidential and legally protected under applicable law. The message is intended solely for the addressee(s). If you are not the intended recipient, you are hereby notified that any use, forwarding, dissemination, or reproduction of this message is strictly prohibited and may be unlawful. If you are not the intended recipient, please contact the sender by return e-mail and destroy all copies of the original message.

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Type arithmetic library?
by Peng Yu 12 Jun '10

12 Jun '10

Hello, boost typeof library can automatically deduce the type. But I'm interested in finding the nested type. For example, if I have a template S<T1, T2>. I'd like to deduce that it has two template arguments, I'd like to access its template argument by index (say, 0 and 1 for this case). I did a preliminary search, but found no such facilities. I may overlook something. Would you please let me know if there is such a facility in boost? -- Regards, Peng

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[program_options] linking to specific library version requested?
by Diederick C. Niehorster 12 Jun '10

12 Jun '10

Hi All, I use program_options happily. One minor annoyance is that the headers somewhere seems to specify which version of the library (the exact file name) they want to link with. I've tried setting "#define BOOST_PROGRAM_OPTIONS_NO_LIB ON" that I found by googling, but it made no difference. I always get "LINK : fatal error LNK1104: cannot open file 'libboost_program_options-vc100-mt-gd-1_44.lib'". Ideally, I'd like to link with libboost_program_options-vc100-mt-gd.lib so that when I upgrade boost I don't have to change the includes in my project files. More strangely, on one of the three computers I work with, next to the library corresponding to the newest boost version, it always requests to link to **-1_41.lib files as well, complete cleaning and rebuilding from scratch does not solve this. I have observed this with both MSVC2008 and MSVC2010. How can I configure program_options such that I can do the linking myself? Best and thanks! Dee

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Adding include information the reference of typeof
by Peng Yu 12 Jun '10

12 Jun '10

Hi, I feel that that the reference page of typeof can be improved by adding what header file should be included. Could the authors add such information in the future? -- Regards, Peng

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[boost/Quickbook] Build documentation with several files
by Carlos Guimarães 12 Jun '10

12 Jun '10

Hi, I have several *.qbk files and I want to build documentation of all of them at one time. They are all in the same folder, so I use the same Jamfile for each one: *using quickbook ; import boostbook : boostbook ; # Intro xml intro : src/intro.qbk ; # Libraries xml base_lib : src/libs/base.qbk ; # App xml client : src/app/client.qbk ; boostbook documentation : intro : <dependency>css ; boostbook lib : base_lib : <dependency>css ; boostbook client : client : <dependency>css ; install css : [ glob ./*.css ] : <location>../html ; explicit css ;* However, they have been building at the same root folder. That fact left me only one index file, because the previous one have been overwrite. How can I resolve it? Thanks

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BOOST_FOREACH infinite loop issue
by yabcok 11 Jun '10

11 Jun '10

Hi, I have a problem with BOOST_FOREACH never ending under specific conditions described here: http://stackoverflow.com/questions/2881491/need-help-with-boost-foreach-com… Could anyone help me understand what's going on? Best regards, Jacek Ławrynowicz

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boost::function, pointer to a member function.
by Mikhail Tatarnikov 11 Jun '10

11 Jun '10

Hi guys, Is there a way to make boost::function to be passed to a function required a pointer to a member function as parameter: struct CFoo { int foo1(int){} int foo2(int, double){} }; int g(int (CFoo::*)(int)); int main() { g(&CFoo::foo1); g(boost::bind(&CFoo::foo2, _1, _2, 666)); // Doesn't compile - boost::bind returns an object instead of function pointer // The following doesn't compile - can't convert from int (*)(CFoo*, int) to int (CFoo::*)(int) g(boost::function<int (CFoo*, int)>( boost::bind(&CFoo::foo2, _1, _2, 666) ).target<int (CFoo*, int)>() ) } The initial problem is to bind a parameter to a member function. It's easy to solve the problem by changing g(), e.g.: template<typename Functor> int g(Functor fun); but is it possible to solve the problem is g() can't be changed? Regards, Mike.

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[thread] mingw32: multiple definition of __tls_used
by Frédéric Bron 11 Jun '10

11 Jun '10

I have some troubles with mingw32 (compiling from cygwin with g++ 3.4.4): The code below fails at link with following error message: /usr/lib/gcc/i686-pc-mingw32/3.4.4/../../../../i686-pc-mingw32/lib/libmingw32.a(tlssup.o):tlssup.c:(.tls+0x0): multiple definition of `__tls_used' /cygdrive/d/Softs/1.7/mgw-release/boost/lib/libboost_thread_win32.a(tss_pe.o):tss_pe.cpp:(.rdata$T+0x0): first defined here collect2: ld returned 1 exit status #include <boost/thread/tss.hpp> int main() { boost::thread_specific_ptr<int> tsp; return 0; } Compiling command was: $ g++-3 -o toto -O3 -DNDEBUG -mno-cygwin -mthreads -DBOOST_WINDOWS_API -I/cygdrive/d/Softs/1.7/mgw-release/boost/include toto.cc -L/cygdrive/d/Softs/1.7/mgw-release/boost/lib -lboost_thread_win32 Recently, mingw32 runtime was updated for cygwin with the following message: > Implement TLS Callback. > > * tlsmcrt.c: New file. > * tlsmthread.c: Ditto. > * tlssup.c: Ditto. > * tlsthrd.c: Ditto. > * Makefile.in: Include new files. > * crt1.c: Implement TLS Callback. > * dllcrt1.c: Ditto. > * mthr_stub.c: Remove. Any clue? Frédéric

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