June 2008 - Boost-users - lists.preview.boost.org

boost::function<Signature>
by Ryan Lovelett 25 Jun '08

25 Jun '08

I've been trying to track down what the maximum number of arguments that can be added to boost::function<> is. I'm starting to believe that the maximum number is 10 arguments. As it seems that when I input 11 arguments VS complains with this error: Error 1 error C2079: 'my_func' uses undefined class > 'boost::function<Signature>' > Error 2 error C2440: 'initializing' : cannot convert from 'void > (__cdecl *)(const char *,affine_transformation_range > *,int,int,double,int,int,int,int,int,char)' to 'int' > My declaration looks like as follows: function<void (const char*,affine_transformation_range*,int,int,double,int,int,int,int,int,char)> my_func(&XClass:build_with_cache_pool); My member function is given by: static void build_with_cache_pool(const char * image_name, affine_transformation_range * range, int maximum_number_of_points_on_model,int number_of_generated_images_to_find_stable_points, double minimum_number_of_views_rate, int patch_size, int yape_radius, int number_of_octaves, int number_of_ferns, int number_of_tests_per_fern, char temp); Any help with this project would be greatly appreciated. -- Thanks, Ryan Lovelett

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Mixing versions of boost
by dariomt＠gmail.com 25 Jun '08

25 Jun '08

Hi all, I'm using header-only boost libs in two static libraries that will be linked into an executable. No boost components are used in the interfaces of those libs, boost is only used in the implementation inside the libraries. Is it possible to mix versions of boost in those two static libraries? Will the linker complain, or will it just get confused and mess up the executable? The problem here is that one of those libraries is 'external', that is, I'm getting it compiled and with no source code (only .h for interface) TIA PS: I admit this is more a C++ linker question, but maybe someone out there has had to coexist with different versions of boost

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How can i use boost in mingw in windows XP
by wang wenhua 25 Jun '08

25 Jun '08

Hi， I would like to use boost in mingw in windows XP, But i do not know how to do it. Could anyone help me? thanks:) Sincerely yours

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Standear deviation
by Sean Farrow 25 Jun '08

25 Jun '08

Hi: Is ther a way in boos to calculate the standard deviation of a dataset with a container? Sean. __________ Information from ESET NOD32 Antivirus, version of virus signature database 3215 (20080624) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com

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[iostreams] first look surprises
by Gennadiy Rozental 25 Jun '08

25 Jun '08

Hi, I've looked at iostream library for the first time in a long while and had couple surprises waiting for me right at doorstep (I am boost 1.33.1 under vc 7.1 io=boost::iostream). 1) io::array_source( "Hello World!" ) doesn't compile 2) io::array_source( std::string( "Hello World!" ) ) doesn't compile 3) can't seem to find toupper and similar filters as part of the library 4) Given line filter like this: struct toupper_line_filter : io::line_filter { virtual std::string do_filter( const std::string& line ) { std::string result; result.reserve( line.size() ); for( std::string::size_type i = 0, size = line.size(); i < size; ++i ) result.push_back( std::toupper((unsigned char)line[i]) ); return result; } }; Following code seems to produce an error std::string result; io::filtering_ostream out; out.push( toupper_line_filter() ); out.push( io::back_inserter(result) ); out << "Hello World!"; BOOST_CHECK_EQUAL( result, "HELLO WORLD!\n" ); 5) my next attempt was to add flush before check - still the same result std::string result; io::filtering_ostream out; out.push( toupper_line_filter() ); out.push( io::back_inserter(result) ); out << "Hello World!"; out.flush() BOOST_CHECK_EQUAL( result, "HELLO WORLD!\n" ); It appears flush had no effect whatsoever. After long battle i found that reset seems to do the trick. But what if I do not want to destroy stream 6) out.sync() doesn't seems to compile, in spite of what docs say 7) stringstream can't be used at sink: std::stringstream buffer; io::filtering_ostream out; out.push( buffer ); fails to compile 8) library seems to have it's own mind about when to invoke my filter. Can I enforce to be called manually? Thanks, Gennadiy

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Debugging shared_ptr usage
by Mike Gibson 24 Jun '08

24 Jun '08

I've got a "leak" with shared_ptr. Basically, I'm pretty sure something is holding onto a reference via shared_ptr I don't want it to. Is there any sort of easy way to track the creation and deletion of shared_ptr's throughout my program to see who is creating shared_ptr's, when they're getting deleted and the reference count being decremented or incremented? Then I can see who is still holding the reference. Thanks, Mike Gibson

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Serialization allocator
by Stuart Reynolds 24 Jun '08

24 Jun '08

I'm interested in using Boost's serialization for a middleware library that receives allocators from the application that uses it. Is it possible to specify which allocators for the serialization library to uses? I can't override global new/delete -- the application reserves the right to do this. Cheers, - Stuart

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Please advise how to sort and store sorted indices
by Jeremy Conlin 24 Jun '08

24 Jun '08

I am using a uBlas vector and need to sort the values. I have another container with elements that are correlated with the uBlas vector. This container must be sorted with the uBlas vector. I want to make some compressed_pairs of the values of the vector and the original index in the vector. These pairs are sorted by the value, after which I can just look at the index of the value to know where it was originally. The problem is that this would require copying the elements of the ublas vector at least twice. Is there anyway I can sort the uBlas vector and keep track of the indices so I can then sort my container–without copying the data multiple times? Thanks, Jeremy (I hope this wasn't too confusing :P.)

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boost::iostreams::copy() closes the sink and source?
by Melville, Ryan 24 Jun '08

24 Jun '08

Hi, While upgrading from boost 1.34.1 to boost 1.35.0 we encountered an issue with boost::iostreams. It seems that boost::iostreams::copy() closes its Source and Sink input parameters once it completes its copy. This seems to be a problem for us because copy() is not the last thing we want to do with our Sinks; we copy() into them but then also put more stuff in them (which now fails). This seems like a natural use case to me... Does anyone know why boost::iostreams::copy() feels the need to close the Source and Sink passed to it? It seems to me that it should not. The caller may or may not want them closed after the copy() and this behavior precludes using copy() as anything other than the last thing you want to do with a Sink. BTW, the apparent intended behavior of copy() is not different in this regard between 1.34.1 and 1.35.0. Rather, the trigger here was that our boost::iostreams::filtering_ostream derived classes are now "closable" by virtue of the "closable_tag" being added to the boost::iostreams::filtering_ostream base class' "categories". Once they became "closeable", copy()'s invocation of close() actually resulted in a close() on them instead of just a flush(). Any insight would be greatly appreciated. Unless I hear some rational for the current behavior I'm inclined to change copy() to not close its Source and Sink. For backwards compatibility, I suppose a "bool close = true" input parameter could be added. That would allow one to override the existing behavior without changing the current behavior on existing code. Although, it really doesn't seem natural to have something called "copy()" close its input parameters and I'm sure the unwary will get burned like us when subsequent uses of the Sink fail unexpectedly. Also, I'm not sure how this interacts with "const" inputs. The documentation implies that copy() also works with a const Source or const Sink, but I haven't tried that. It could not close a const Source or Sink, right? And it could not even write into a const Sink so I'm not sure what the purpose of that input combination would be. Regards, Ryan Ryan Melville Email: Office: Fax: Xiotech Corporation 6455 Flying Cloud Drive Eden Prairie, MN 55344 United States www.Xiotech.com <http://www.xiotech.com/> : Toll-Free 866 472 6764

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Linking error using boost::thread - start_thread undefined
by Wayne Russell 24 Jun '08

24 Jun '08

Hi All I'm new to using Boost and have a (hopefully simple) linker problem. I'm compiling using gcc 4.2.1 under OpenSUSE 10.3 and get the following: --- Invoking: GCC C++ Linker g++ -o"TestTransporter" ./src/TestTransporter.o -lrt -lpthread -lboost_thread ./src/TestTransporter.o: In function `thread<void (*)()>': /usr/include/boost/thread/pthread/thread.hpp:151: undefined reference to `boost::thread::start_thread()' --- The code is quite simple: --- #include <iostream> #include <string> #include <boost/thread/thread.hpp> void foo () {}; int main(int argc, char *argv[]) { std::cout << "!!!Hello World!!!" << std::endl; // prints !!!Hello World!!! boost::thread test_thread (&foo); return 0; } --- I've compiled the thread tests all ok and used the "-d+2" option but couldn't see any additional link options that I don't already have. Can anyone shine light on this for me? Regards, WR

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