June 2010 - Boost-users - lists.boost.org

Build Questions
by John Dlugosz 08 Jun '10

08 Jun '10

I have two related questions. First, how can my source file assert that the correct version of Boost was found for an #include? Second, I need to build Microsoft debug DLLs to match incompatible compilation options, namely defines _HAS_ITERATOR_DEBUGGING=0;_BIND_TO_CURRENT_VCLIBS_VERSION=1. How should I decorate the resulting names to reflect this option? That is, besides ...-mt-dg...? I think this is referred to as the "ABI tag". --John TradeStation Group, Inc. is a publicly-traded holding company (NASDAQ GS: TRAD) of three operating subsidiaries, TradeStation Securities, Inc. (Member NYSE, FINRA, SIPC and NFA), TradeStation Technologies, Inc., a trading software and subscription company, and TradeStation Europe Limited, a United Kingdom, FSA-authorized introducing brokerage firm. None of these companies provides trading or investment advice, recommendations or endorsements of any kind. The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any computer.

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Problem with -Wall and Property Tree
by José Tomás Tocino García 08 Jun '10

08 Jun '10

Hi there, I've started to use boost::property_tree to parse some ini files, and I'm getting an error when I compile using -Wall on gcc 4.4.3. For this testcase: #include <boost/property_tree/ptree.hpp> #include <boost/property_tree/ini_parser.hpp> #include <iostream> using namespace std; class Reader{ boost::property_tree::ptree myTree; public: Reader(){ read_ini("config.ini", myTree); cout << myTree.get<float>("sonido.limite", 0.); } }; int main(int argc, char *argv[]) { Reader r; } If I compile using "g++ -o program testcase1.cpp -I." I get no errors, but if I add "-Wall", I get: ./boost/property_tree/detail/ptree_implementation.hpp: In function ‘int main(int, char**)’: ./boost/property_tree/detail/ptree_implementation.hpp:728: warning: dereferencing pointer ‘default_value’ does break strict-aliasing rules /usr/include/boost/optional/optional.hpp:422: note: initialized from here What's the problem? It compiles and works properly, but it would be great to have a warning-free compilation output. Thanks in advance. -- José Tomás Tocino García

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[thread] Is Boost suitable for this application?
by Francisco Javier Porras Gálvez 08 Jun '10

08 Jun '10

Hi, all. I don't know anything about Boost, neither OpenMP, pthread nor Windows API thread library. So, before begin learning one of these, I'd like to explain to you how I want my application to work. It deals with running two parallel loops, one in LabView, and the other in C++. It doesn't matter if you don't know anything about LabView, this explanation is easy enough to understand. Attached you can see a picture which shows the desired execution behaviour. I want to know whether my application would be possible to achieve using Boost, or using another API. In another general C++ forum, I was suggested to use Boost. First, the execution begins in LabView. Here, I call a dll function written in C++. This is the "initialization" function. Its aim is to create another thread that will execute the main loop in C++. Then, this "initialization" function ends, because it has to return the control execution to LabView, but the new thread which has just been created must continue executing in its own loop. Now we have two loops in parallel: LabView and C++. In LabView's loop, we call periodically another dll function that has to send and retrieve data from the independent thread in C++. This function, like the other, has to end executing to pass control to LabView again, after it has done its purpose. This will be the behaviour until we call from LabView another dll function to stop the independent thread (not shown in the picture). After this, the LabView program ends. Is it possible to use Boost for this? If so, could you post a brief example about how you'd make it? Thanks in advance, Francisco

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[GIL] Some questions about 2D iteration
by Brett Gmoser 08 Jun '10

08 Jun '10

Hello everybody, I've been toying with GIL a bit for the last few days in my spare time, and I've got a few questions that I can't seem to find answers to in the documentation. The following function which I've written works, but I'd like to get a better understanding of how to use iterators to accomplish the same task (the documentation says that view(x, y) = z is inefficient), as well as a few other things. The job of this function is to crop an image, discarding any white background. In other words, find the top-most, left-most, right-most, and bottom-most pixel that isn't the background color (white), and crop the image around those coordinates. template <typename ViewType, typename ImageType> void crop_image(ViewType& src, boost::scoped_ptr<ImageType>& dst) const { int top = 0; int right = 0; int bottom = 0; int left = 0; // Find the top, right, bottom, and left extents. First, find the top. for(int y=0; y < src.height(); ++y) { for(typename ViewType::x_iterator xpos = src.row_begin(y); xpos != src.row_end(y); ++xpos) { if(rgb8_pixel_t(255,255,255) != *xpos) { top = y; break; } } if(top) break; } // ... Do similar things for finding the right, bottom, and left extents. // We should now have the rectangle of the image, and it should be easy to copy everything over. dst.reset(new ImageType(1 + (right - left), 1 + (bottom - top))); for(int x = left; x <= right; ++x) for(int y = top; y <= bottom; ++y) view(*dst)((x - left), (y - top)) = src(x, y); } So, my first question is - is there a better way to do that first chore of finding each extent? Such as a way to use std::find or std::find_if, keeping in mind that I have to do two of the four sides in reverse (bottom-to-top to find bottom-most, right-to-left to find right-most)? The next question is about the final loop which copies from the source view to the newly created destination image. It seems that using iterators, I could do something like this, assuming that I had the above loops find iterator positions for all four extents (left, top, bottom, and right are iterators): // Start the copying process by creating a column iterator for the destination table beginning at column 0. // The top iterator starts at the top-most extent - and we cycle through the source image in a top-to-bottom, // left-to-right fashion. for(typename ImageType::view_t::y_iterator dst_y = view(*dst).col_begin(0); top <= bottom; ++dst_y,++top) { // The left iterator needs to be initialized with whatever row we're on - this appears to be impossible. There doesn't // seem to be any suitable way to do this, so consider it pseudocode. typename ViewType::x_iterator src_x = left.y(); // The destination X iterator also needs to know what Y position to begin on. You'd think you would be able to initialize // it with an iterator position, but it doesn't seem that you can. Again, this doesn't actually compile (it's the // view(*dst).row_begin(y) part). for(typename ImageType::view_t::x_iterator dst_x = view(*dst).row_begin(y); // Here, I need to be able to tell if src_x has hit the right extent. src_x <= right doesn't seem it will work, because // again right doesn't know it's Y position. src_x != right; // And increment both src and destination iterators. ++src_x,++dst_x ) { // Finally do the should-be-simple task of assigning the source pixel to the destination pixel. *dst_x = *src_x; } } If you read the comments, most of this doesn't seem to be possible. I've seen that there is a "transform_pixel_positions" algorithm that may do something close to what I want, but unfortunately I cannot find any documentation on it (other than mentioning that it exists, and a short example that really doesn't help - one of the few examples actually provided by the documentation). It seems to pass a unary argument to a functor, but that doesn't seem useful if I don't have both the X and Y coordinates, or an X iterator and Y iterator. Also, nowhere can I find where it says what the argument passed to the functor actually /is/. So after I figure these few things out, I'm hoping to be able to speed up my program a little bit. Right now everything is pretty slow using that view(x, y) method. I'd appreciate any help that anybody can give, thanks! Brett

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get/set RTS on serial port
by Marcelo Adrian Lorenzati Sanz 08 Jun '10

08 Jun '10

Hi, As far as I've seen in the boost user mailing page, the topic about getting / setting the RTS and other control lines for the serial port have been already discussed, but my question is if it is planned to be added to boost asio serial port the control of those lines by the get_option / set_option. If not, how can I implement my own set_option to control the RTS line in a way to allow me to use it multiplatform, is there any example, hint, mock class, etx? The serial port is still very used in embedded designs and boost is the best way to go to connect with the pc. Best regards, Marcelo Lorenzati

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Illegal instruction with Boost program options and Visual Studio 2008
by Basil Crow 07 Jun '10

07 Jun '10

Dear list, I am having some trouble using the Boost program options library with Visual Studio 2008 on Windows 7 (64-bit). My program is as follows: #include <boost/program_options.hpp> int wmain(int argc, wchar_t* argv[]) { boost::program_options::basic_command_line_parser<wchar_t> parser(argc, argv); return 1; } I compiled and linked the above as follows: > cl testcase.cpp /c /I "C:\dev\boost-1.42.0\include" /EHsc /Zi Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 15.00.21022.08 for 80x86 Copyright (C) Microsoft Corporation. All rights reserved. testcase.cpp > link testcase.obj /LIBPATH:"C:\dev\boost-1.42.0\lib" /DEBUG Microsoft (R) Incremental Linker Version 9.00.21022.58 Copyright (C) Microsoft Corporation. All rights reserved. When running the program, on line 504 of function_template.hpp I encounter an "Unhandled exception at 0x0018ffc4 in testcase.exe: 0xC000001D: Illegal Instruction." Please advise me as to how I can resolve this issue. Thank you, Basil

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Bind questions
by John Dlugosz 07 Jun '10

07 Jun '10

Is the documentation for Boost::Bind matching the std::tr1::bind that got accepted? That is, can I read this to understand it since the docs are better than what comes with the compiler, or are there differences? Consider a member function C::foo. If I want to bind the object this parameter but leave the rest unchanged, would bind(&C::foo,x) automatically give me bind(&C::foo,x,_1,_2,_3)? What if I want to call x->foo(5,_3) and not use the first two parameters or the 4th, to make something that is passed to a callback function that wants 4 arguments? That is, the callback F is invoked F(a,b,c,d) and I want to make a function instance that can be assigned to F, and ends up calling x->foo(5,c). --John TradeStation Group, Inc. is a publicly-traded holding company (NASDAQ GS: TRAD) of three operating subsidiaries, TradeStation Securities, Inc. (Member NYSE, FINRA, SIPC and NFA), TradeStation Technologies, Inc., a trading software and subscription company, and TradeStation Europe Limited, a United Kingdom, FSA-authorized introducing brokerage firm. None of these companies provides trading or investment advice, recommendations or endorsements of any kind. The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any computer.

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[Range] Documentation for the combine function
by Sorin Fetche 07 Jun '10

07 Jun '10

Hi, While looking for a Boost.Range counterpart to the zip_iterator, I found the combine() function in boost/range/combine.hpp. But I didn't find any associated documentation neither in Boost 1.43 nor in trunk. In case I didn't overlook it, can I get a confirmation that this function really belongs to the public API, thus being safe to use? Thank you, Sorin

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build problems on Mac OS with MacPorts gcc
by Rob Nikander 07 Jun '10

07 Jun '10

Hi, I'm on OS X, and I have a gcc 4.5 from macports (because I wanted C++0x features). I downloaded boost and compiled the regex library, but used the default boost build commands so it used apple's gcc, which led to weird bug when linked to a program created with gcc4.5. (Maybe that's not supposed to happen? I can start another thread about that.) Now I'm trying to build boost with the gcc 4.5, but that doesn't work... I followed these instructions to build bjam: http://www.boost.org/doc/libs/1_43_0/doc/html/jam/building.html I also edited a 'user-config.jam' to have: using gcc : 4.5 : g++-mp-4.5 ; Then went to BOOST_ROOT and ran: bjam toolset=gcc stage And it eventually barfs with this: gcc.link.dll bin.v2/libs/regex/build/gcc-4.5/release/threading-multi/libboost_regex.dylib ld: unknown option: -h collect2: ld returned 1 exit status Any ideas? thanks, Rob

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[gil io_new] Problem writing a compressed jpeg
by Olivier Tournaire 07 Jun '10

07 Jun '10

Hi all, I am currently trying to write a compressed jpeg image without any success. Here is my code: #include <string> #include <boost/mpl/vector.hpp> #include <boost/gil/gil_all.hpp> #include <boost/gil/extension/io_new/tiff_read.hpp> #include <boost/gil/extension/io_new/tiff_write.hpp> #include <boost/gil/extension/io_new/jpeg_read.hpp> #include <boost/gil/extension/io_new/jpeg_write.hpp> using namespace std; using namespace boost; using namespace gil; int main(int argc, char** argv) { string base_image_path(argv[1]); string output_image_path(argv[2]); string output_compressed_image_path(argv[3]); typedef mpl::vector< rgb8_image_t, rgb16_image_t > rgb_image_types; typedef any_image<rgb_image_types> any_image_type; typedef any_image_type::view_t any_view_type; // Read tiff image image_read_info< tiff_tag > info = read_image_info( base_image_path , tiff_tag() ); any_image_type input_image; read_image(base_image_path.c_str(), input_image, tiff_tag()); write_view(output_image_path.c_str(), view(input_image), jpeg_tag()); image_write_info< jpeg_tag > compressed_jpeg_info; compressed_jpeg_info._quality = 30; //compressed_jpeg_info._dct_method = jpeg_dct_method::fastest; write_view(output_compressed_image_path.c_str(), view(input_image), compressed_jpeg_info); } Could you please help me ? Regards, Olivier

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