April 2009 - Boost-users - lists.boost.org

BLL: ::toupper( _1) generates C2664
by Suman Kar 11 Apr '09

11 Apr '09

I have just started with BLL. The following sample shows where I am stuck: #include <string> #include <cctype> #include <boost/lambda/bind.hpp> #include <boost/lambda/lambda.hpp> int main() { using namespace std; using namespace boost::lambda; string s("hello, world"); for_each(s.begin(), s.end(), _1 = ::toupper(_1)); return 0; } I hit a C2664: cannot convert parameter 1 from 'boost::lambda::placeholder1_type' to 'int'. I am using VS2005. Unfortunately, I do not have access to gcc at the moment to validate this (dig further). Of course, I can get the sample to work if I change the for_each invocation to use a bind: for_each(s.begin(), s.end(), _1 = bind(::toupper, _1)); Regards, Suman

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[boost.python] ImportError: DLL Load failed.
by Germán Diago 11 Apr '09

11 Apr '09

Hello. I compiled a python module with msvc for python2.6 under windows xp. Under linux everything's ok, but under windows xp, I don't know what happens, I get an ImportError: DLL Load failed. I set sys.path to the directory containing the module, but no luck until now. Is it a problem with boost.python. I don't know what to think. Thanks for your help.

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[range_ex] range adaptor and boost::lambda
by 041021042 10 Apr '09

10 Apr '09

Hi, Thanks for solving my previous find() problem. I found another problem of range_ex. The following code still works well with the old version of range_ex (Dec 2008), and cause a compile error with the newest version. code: #include <boost/range/adaptor/filtered.hpp> #include <boost/range/algorithm.hpp> #include <boost/lambda/lambda.hpp> #include <boost/lambda/bind.hpp> #include <boost/assign.hpp> #include <iostream> #include <vector> bool is_even(int x) { return x % 2 == 0; } int main() { using namespace boost::assign; using namespace boost::adaptors; using namespace boost::lambda; std::vector<int> input; input += 1,2,3,4,5,6,7,8,9; boost::copy( input | filtered(bind(is_even, _1)), std::ostream_iterator<int>(std::cout, ",") ); return 0; } compiler: msvc2008 error messages: d:\software\boost_1_37_0\boost\lambda\detail\lambda_traits.hpp(389) : warning C4180: qualifier applied to function type has no meaning; ignored d:\software\boost_1_37_0\boost\lambda\detail\lambda_traits.hpp(458) : see reference to class template instantiation 'boost::lambda::detail::bind_traits<T>' being compiled with [ T=bool (int) ] e:\zxg\boost\range_ex\range.cpp(20) : see reference to class template instantiation 'boost::lambda::detail::bind_tuple_mapper<T0,T1,T2,T3,T4,T5,T6,T7,T8,T9>' being compiled with [ T0=bool (int), T1=boost::lambda::placeholder1_type, T2=boost::tuples::null_type, T3=boost::tuples::null_type, T4=boost::tuples::null_type, T5=boost::tuples::null_type, T6=boost::tuples::null_type, T7=boost::tuples::null_type, T8=boost::tuples::null_type, T9=boost::tuples::null_type ] d:\software\boost_1_37_0\boost\tuple\detail\tuple_basic.hpp(383) : error C3853: '=': re-initializing a reference or assignment through a reference-to-function is illegal d:\software\boost_1_37_0\boost\tuple\detail\tuple_basic.hpp(382) : while compiling class template member function 'boost::tuples::cons<HT,TT> &boost::tuples::cons<HT,TT>::operator =(const boost::tuples::cons<HT,TT> &)' with [ HT=bool (__cdecl &)(int), TT=boost::tuples::cons<const boost::lambda::lambda_functor<boost::lambda::placeholder<1>>,boost::tuples::detail::map_tuple_to_cons<boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>::type> ] d:\software\boost_1_37_0\boost\tuple\detail\tuple_basic.hpp(526) : see reference to class template instantiation 'boost::tuples::cons<HT,TT>' being compiled with [ HT=bool (__cdecl &)(int), TT=boost::tuples::cons<const boost::lambda::lambda_functor<boost::lambda::placeholder<1>>,boost::tuples::detail::map_tuple_to_cons<boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>::type> ] d:\software\boost_1_37_0\boost\lambda\detail\lambda_functor_base.hpp(398) : see reference to class template instantiation 'boost::tuples::tuple<T0,T1,T2,T3,T4,T5,T6,T7,T8,T9>' being compiled with [ T0=bool (__cdecl &)(int), T1=const boost::lambda::lambda_functor<boost::lambda::placeholder<1>>, T2=boost::lambda::detail::bind_traits<boost::tuples::null_type>::type, T3=boost::lambda::detail::bind_traits<boost::tuples::null_type>::type, T4=boost::lambda::detail::bind_traits<boost::tuples::null_type>::type, T5=boost::lambda::detail::bind_traits<boost::tuples::null_type>::type, T6=boost::lambda::detail::bind_traits<boost::tuples::null_type>::type, T7=boost::lambda::detail::bind_traits<boost::tuples::null_type>::type, T8=boost::lambda::detail::bind_traits<boost::tuples::null_type>::type, T9=boost::lambda::detail::bind_traits<boost::tuples::null_type>::type ] d:\software\boost_1_37_0\boost\lambda\detail\lambda_functors.hpp(113) : see reference to class template instantiation 'boost::lambda::lambda_functor_base<Act,Args>' being compiled with [ Act=boost::lambda::action<2,boost::lambda::function_action<2,bool>>, Args=boost::tuples::tuple<bool (__cdecl &)(int),const boost::lambda::lambda_functor<boost::lambda::placeholder<1>>,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples: :null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type> ] e:\zxg\boost\range_ex\range.cpp(20) : see reference to class template instantiation 'boost::lambda::lambda_functor<T>' being compiled with [ T=boost::lambda::lambda_functor_base<boost::lambda::action<2,boost::lambda::function_action<2,bool>>,boost::tuples::tuple<bool (__cdecl &)(int),const boost::lambda::lambda_functor<boost::lambda::placeholder<1>>,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detai l::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type>> ] Thanks, Roger Zhou

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[GIL] How can I in-place convert some part of view to grayscale.
by blp330 10 Apr '09

10 Apr '09

Hi, I have a rgb8_image_t::view_t view, and I want to convert some part of it to grayscale within its region, for example: 0,0,100,100 (x,y,width,height) How can I do this? I try to do this but it can't be compiled. typedef boost::gil::pixel< typename boost::gil::channel_type< boost::gil::rgb8_image_t::view_t>::type, boost::gil::gray_layout_t> gray_pixel_t; boost::gil::copy_pixels( boost::gil::color_converted_view<gray_pixel_t>( boost::gil::subimage_view(view, x, y, width, height)), boost::gil::subimage_view(view, x, y, width, height)); Thank you very much. -- View this message in context: http://www.nabble.com/-GIL--How-can-I-in-place-convert-some-part-of-view-to… Sent from the Boost - Users mailing list archive at Nabble.com.

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BoostCon 2009 Early Registration Still Available
by David Abrahams 10 Apr '09

10 Apr '09

In recognition of the economic climate, and in order to make possible the maximum participation this year, we've extended the early registration deadline for BoostCon until April 26th, so BoostCon is still only $599. BoostCon has always been a great place to network, find out what is happening in the C++ community, and learn about the coolest C++ libraries being developed within and outside of Boost --- and this year will be better than ever. The official schedule is now live at http://www.boostcon.com/program. A few highlights of the "mouth-watering content" (in the words of one enrollee) are: * A keynote address from Andrei Alexandrescu called "Iterators Must Go." * Troy Straszheim's presentations on how high-energy physicists are using Boost to process massive datasets as they go "Icefishing for Neutrinos" and on Kamasu, his library for offloading computation to your machine's GPU. * Two hands-on sessions where we'll start recoding parts of Boost for C++0x, applying rvalue references, variadic templates, decltype, and advanced SFINAE capabilities using the latest GCC. * "Practical C++ Test-Driven Development with Boost.Test and Bmock," by Asher Sterkin * A session on compiler construction using Boost.Spirit v2, from Hartmut Kaiser and Joel de Guzman The complete list of sessions covers a wide range of other Boost and C++-related topics. Please have a look: http://www.boostcon.com/program/sessions. The quality of BoostCon has always depended on its diverse and interesting participants, so bring your ideas, questions, and experience, and sign up now! http://www.boostcon.com/registration See you in Aspen, -- Dave Abrahams BoostPro Computing http://www.boostpro.com

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[extension]: g++ '-O2' optimization w/ type_map access thru member template function
by Jeffrey Chang 10 Apr '09

10 Apr '09

Hi, I'm a happy user of boost::extension library. Thanks Jeremy Pack et al. for this great work, and hope it'll be accepted by Boost soon. My extension library is dowloaded from http://boost-extension.blogspot.com/ (August 14, 2008 Link), which works great for me when compiled with "-O0" optimization flag in g++ (my version: i686-apple-darwin9-g++-4.0.1). But, when I compile with -O2 and access type_map object through member template function, g++ seems to optimize away the initialization logic for 'type_map', and I'd get signal assertion of EXC_BAD_ACCESS. Here's my test program: 65 struct MyDict { 66 boost::extensions::type_map mTypeDict; 67 template< typename T > 68 T & refInstance() { mTypeDict.get<T>(); } 69 }; 70 71 typedef std::set<int> IntSetType; 72 73 void test_MyDict_1_mem_data_access() { 74 MyDict testObj; 75 std::cout << "------ 1 " << std:: endl; 76 IntSetType &rIntSet = testObj.mTypeDict.get<IntSetType>(); 77 std::cout << "------ 2 " << std:: endl; 78 std::cout << "rIntSet.size() is " << rIntSet.size() << std::endl; 79 std::cout << "------ 3 " << std:: endl; 80 rIntSet.insert (123); 81 std::cout << "------ 4 " << std:: endl; 82 std::cout << "rIntSet.size() is now " << rIntSet.size() << std::endl ; 83 std::cout << "------ 5 " << std:: endl; 84 } 85 86 void test_MyDict_2_mem_func_access() { 87 MyDict testObj; 88 std::cout << "====== 1 " << std:: endl; 89 IntSetType &rIntSet = testObj.refInstance<IntSetType>(); 90 std::cout << "====== 2 " << std:: endl; 91 std::cout << "rIntSet.size() is " << rIntSet.size() << std::endl; 92 std::cout << "====== 3 " << std:: endl; 93 rIntSet.insert (123); 94 std::cout << "====== 4 " << std:: endl; 95 std::cout << "rIntSet.size() is now " << rIntSet.size() << std::endl ; 96 std::cout << "====== 5 " << std:: endl; 97 } This test program runs without any problem when compiled with "-O0"; but with "-O2" compiler flag, "test_MyDIct_1_mem_data_access()" is still run ok as expect, but "test_MyDict_2_mem_func_access()" halts at line 93. Here's the output when run under gdb: ------ 1 ------ 2 rIntSet.size() is 0 ------ 3 ------ 4 rIntSet.size() is now 1 ------ 5 ====== 1 ====== 2 rIntSet.size() is 86 ====== 3 Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_PROTECTION_FAILURE at address: 0x0000005e std::_Rb_tree<int, int, std::_Identity<int>, std::less<int>, std::allocator<int> >::insert_unique (this=0x56, __v=@0xbffff24c) at testHpcDictByType.c:871 871 _Link_type __x = _M_begin(); (gdb) So my question is, what's wrong with accessing boost::extension::type_map through "MyDict::refInstance<T>()" here? In g++ "-O2" mode, why does the direct access to "MyDict::mTypeDict" is ok, while "MyDict::refInstance<T>()" is not ? I'm not sure if this is a generic g++ optimization problem, or specific to boost::extension library. But, for me, it seems to happen only for type_map data structure, but not others. Thanks for shedding any light on this. --- Jeffrey

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smaller / decoupled `filesystem' module?
by tom fogal 10 Apr '09

10 Apr '09

I recently had a need to fix some code which got a list of files in a directory, and needed to work across Linux / OS X 10.4+ / Windows. I was thinking of unifying it to use boost filesystem instead of some `#if not posix, do this, #else use opendir/readdir/etc. code.' So I turned to boost.filesystem. We're including boost piecemeal in our repo, and so I went to add it and adapt `filesystem' to our build system. Upon build, it seemed to require some additional boost headers, so I added them; goto 10. After a bit of this, I realized the new boost code was quite a bit larger than my entire ~5 meg repository up to that point: I'd needed to pull in MPL, for example, which is over > 6 meg. This is a minor part of the application we're writing, so I can't really justify the size. Has anybody out there written a `decoupled' filesystem, with less dependencies on other boost libraries? Even a trimmed down version would probably suit or needs for quite some time. Thanks, -tom

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choosing boost libs to link on iPhone based on selected OS target?
by Kenny Riddile 10 Apr '09

10 Apr '09

I've built boost as static libs for both iPhone(ARM) and the iPhone simulator(x86). I'm trying to figure out how to configure XCode so that it will know which set of libraries to link against based on which OS target I choose in the IDE. Is there anyone with experience using boost on the iPhone that can shed some light on this? Rene?

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[serialization] save/load split between 2 different classes
by Robert Dailey 10 Apr '09

10 Apr '09

I've got a particular issue I cannot seem to find a solution to. I'm using boost.serialization to deserialize audio data into an object that wraps OpenAL. For example, the data I'm writing out would be (in order) a single INT representing the size of the raw data and then the data buffer after that. However, in my "Sound" object, I do not keep the data and length information as state in the class. Instead, I just keep the OpenAL buffer handle. In order for this class to be able to implement save(), it would need to have extra state, which would not be appropriate. Basically, I need to have a separate object dedicated to saving the sound data, and another for loading it. Is this possible? Perhaps there is a recommended design?

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[ASIO] How to terminate a io_service inside a library.
by Daniele Barzotti 10 Apr '09

10 Apr '09

Hi, I'm sorry if this is not a question specifically about ASIO, but I need a suggestion.. I have a library that can be built like a Dynamic or static. Inside I have the following code: ---------------------------------------------------------- // Main io_service static boost::asio::io_service io_service; static boost::scoped_ptr<boost::thread> io_service_thread; static boost::asio::io_service::work work(io_service); static bool thread_started; EXTERN_C EUROATLIB_API MyObjHandl CALL GetMyObj() { if (!thread_started) { try { // run the IO service as a separate thread io_service_thread.reset(new boost::thread( boost::bind(&boost::asio::io_service::run, &io_service) )); thread_started = !thread_started; } catch (boost::thread_resource_error e) { // Failed to create the new thread return 0; } } // create the new object return new MyObj(io_service); }; ---------------------------------------------------------- Ok, now I need a way to stop the io_service thread when all MyObj are destroyed. In the clients I use: boost::scoped_ptr<MyObj> _devMyObj( GetMyObj() ); How can I accomplish this in a right way? Thanks, Daniele.

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