December 2008 - Boost-users

[boost.tuple] Nested tuples and tie
by Julius Ziegler 18 Dec '08

18 Dec '08

Dear list, is there a way to make constructs like this one work? double a, b, c; tie( tie( a, b ), c ) = make_tuple( make_tuple( 1., 2. ), 3. ); This leads to the first parameter of the "outer" tie getting initialised by the return value of the "inner" tie. That means a temporary gets passed by reference, and the compiler (sort of reasonably) doesnt want to do this. Best regards, Julius

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[bind] Pointer as third parameter
by Jean-Pierre Bergamin 18 Dec '08

18 Dec '08

Dear boost-Users I'm having problems with calling a function that takes a pointer as the third argument through bind. I cannot explain, why the code below does not compile with the function 'op3' enabled. When changing f3 to void f3(int a, int b, int c) { } it also works. I don't see any reasony why this should fail, since f2 also works. Any ideas how to solve this? // --------------------------------------- void f3(int a, int b, int *c) { } void f2(int a, int *b) { } template <typename F> void op3(F f) { int a = 1, b = 2, c = 3; f(a, b, &c); } template <typename F> void op2(F f) { int a = 1, b = 2; f(a, &b); } void call() { op2(boost::bind(&f2, _1, _2)); //op3(boost::bind(&f3, _1, _2, _3)); } // --------------------------------------- This compiles fine. When uncommenting the line op3(...) in the function "call", gcc fails with: test.cpp: In function `void op3(F) [with F = boost::_bi::bind_t<void, void (*)(int, int, int*), boost::_bi::list3<boost::arg<1> (*)(), boost::arg<2> (*)(), boost::arg<3> (*)()> >]': test.cpp:23: instantiated from here test.cpp:11: error: no match for call to `(boost::_bi::bind_t<void, void (*)(int, int, int*), boost::_bi::list3<boost::arg<1> (*)(), boost::arg<2> (*)(), boost::arg<3> (*)()> >) (int&, int&, int*)' /usr/local/include/boost/bind/bind_template.hpp:18: note: candidates are: typename boost::_bi::result_traits<R, F>::type boost::_bi::bind_t<R, F, L>::operator()() [with R = void, F = void (*)(int, int, int*), L = boost::_bi::list3<boost::arg<1> (*)(), boost::arg<2> (*)(), boost::arg<3> (*)()>] /usr/local/include/boost/bind/bind_template.hpp:24: note: typename boost::_bi::result_traits<R, F>::type boost::_bi::bind_t<R, F, L>::operator()() const [with R = void, F = void (*)(int, int, int*), L = boost::_bi::list3<boost::arg<1> (*)(), boost::arg<2> (*)(), boost::arg<3> (*)()>] /usr/local/include/boost/bind/bind_template.hpp:114: note: typename boost::_bi::result_traits<R, F>::type boost::_bi::bind_t<R, F, L>::operator()(A1&, A2&, A3&) [with A1 = int, A2 = int, A3 = int*, R = void, F = void (*)(int, int, int*), L = boost::_bi::list3<boost::arg<1> (*)(), boost::arg<2> (*)(), boost::arg<3> (*)()>] /usr/local/include/boost/bind/bind_template.hpp:120: note: typename boost::_bi::result_traits<R, F>::type boost::_bi::bind_t<R, F, L>::operator()(A1&, A2&, A3&) const [with A1 = int, A2 = int, A3 = int*, R = void, F = void (*)(int, int, int*), L = boost::_bi::list3<boost::arg<1> (*)(), boost::arg<2> (*)(), boost::arg<3> (*)()>] MSVC 8 fails with: .\test.cpp(19) : error C2664: 'void boost::_bi::bind_t<R,F,L>::operator ()<int,int,int*__w64 >(A1 &,A2 &,A3 &) const' : cannot convert parameter 3 from 'int *__w64 ' to 'int *__w64 &' with [ R=void, F=void (__cdecl *)(int,int,int *), L=boost::_bi::list3<boost::arg<1>,boost::arg<2>,boost::arg<3>>, A1=int, A2=int, A3=int *__w64 ] .\Sleep.cpp(29) : see reference to function template instantiation 'void op3<boost::_bi::bind_t<R,F,L>>(boost::_bi::bind_t<R,F,L>)' being compiled with [ R=void, F=void (__cdecl *)(int,int,int *), L=boost::_bi::list3<boost::arg<1>,boost::arg<2>,boost::arg<3>> ] Thanks for your help. James

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[?] Looking for something like 'data_grid'
by loadcom 18 Dec '08

18 Dec '08

hello all, Sorry for this probable OT post, but I believe the boost guys must be able to help me. :-) I'm looking for a class similar to this: template class data_grid { //... }; It's a data block of arbitrary dimensions. With it user can do thing's like data look up, and interpolate on any series of specified dimentions, and the like. I guess boost doesn't have an out-of-the-box class like this, while multi_array is close to this requirements. Yes, I could write one by myself. But if there's an existing one, I won't bother to reinvent a wheel. Thanks for any information. with best regards Max ------------------------------------------------------------------- 新浪空间——与朋友开心分享网络新生活！(http://space.sina.com.cn/ )

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something about UTF8
by wind world 18 Dec '08

18 Dec '08

hi guys, I want to use boost::regex in Windows XP to match Japanese kanji. The encoding of kanji is UTF-8 I want to make sure after I use the funcation: MultibyteToWideChar to change the UTF-8 Kanji string->wstring, I can directly use boost::wregex(from wstring) to match Japanese? Appreciate any help. Worldwind

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[program options] Constraints, missing options
by Georg Sauthoff 18 Dec '08

18 Dec '08

Hi, I am using boost.Program_options and it is quite useful. I miss two features, though. I could not find a way to specify that some option should be mandatory at the command line. Or that some option has to be present at least x times and at most y times at the command line. I mean I can check it myself if the Program_options parser is finished - but I like it better, if the library would do the work for me. In pseudocode I want to write something like this for example: opts.add_options()("file,f", value< vector<string> >() ->min_times(1)->max_times(2), "blah blah"); ./a.out -f foo -f bar # ok ./a.out -f foo -f bar -f bas # exception from the Program_options parser Is this feature missing, or have I overlooked it in the documentation? Another thing I couldn't find: a way to switch program options into a 'checking mode'; i.e. a mode, where the program options code throws an exception if the count of an non existing option is queried (in case of an programming error). For example desc.add_options() ("help,h", "produce help message"); ... vm.set_pedantic(); // <- pseudo code vm.count("foobar"); // <- would throw exception Or even better, if it is possible do register some enum value, which can be used to index into the variables_map - I mean, to get a compile error the option identifier is misspelled (instead of an runtime error ...): enum my_opts { HELP }; desc.addoptions()("help,h", HELP, "produce help message"); vm.count(EHLP); // <- compile error ... Best regards Georg

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submiting boost patches
by Sean Farrow 18 Dec '08

18 Dec '08

Hi: I am currently working on apatch to th bgl in terms of expat. How do I submit this patch when finished? Any help apreciated. Sean

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something about icu
by wind world 17 Dec '08

17 Dec '08

hi guys, I want to use boost::regex in Windows XP + VC6 to match Japanese . I want to know if I need to enable ICU when I compile boost_1_36_0. In my short test program, I did not enable icu and it still can mathch and replace Japanese. But I do not know it is always right. And if I want to match Japanese I mush enable ICU? Appreciate any help. Worldwind

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newbie question on quickbook install
by Christof Warlich 17 Dec '08

17 Dec '08

Hi, I'd like to use quickbook to document my project, but failed to install it on my system (Ubuntu Hardy Heron). When I run bjam --v2 in BOOST_ROOT/tools/quickbook, I get: generate.jam: No such file or directory ../../Jamroot:383: in modules.load *** argument error * rule path.glob ( dirs * : patterns + ) * called with: ( boost/tr1/tr1 : * : bcc32 sun CVS .svn ) * extra argument bcc32 /usr/share/boost-build/util/path.jam:223:see definition of rule 'glob' being called /usr/share/boost-build/build/project.jam:312: in load-jamfile /usr/share/boost-build/build/project.jam:68: in load /usr/share/boost-build/build/project.jam:120: in load-parent /usr/share/boost-build/build/project.jam:447: in initialize /usr/share/boost-build/build/project.jam:301: in load-jamfile /usr/share/boost-build/build/project.jam:68: in load /usr/share/boost-build/build/project.jam:120: in load-parent /usr/share/boost-build/build/project.jam:447: in initialize /usr/share/boost-build/build/project.jam:301: in load-jamfile /usr/share/boost-build/build/project.jam:68: in load /usr/share/boost-build/build/project.jam:170: in project.find /usr/share/boost-build/build-system.jam:148: in load /usr/share/boost-build/kernel/modules.jam:261: in import /usr/share/boost-build/kernel/bootstrap.jam:132: in boost-build /home/christof/work/boost/boost_1_37_0/boost-build.jam:16: in module scope Can anyone help? Thanks, Christof

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Large buffers in boost::asio SSL
by Scott Gifford 17 Dec '08

17 Dec '08

Hello, We're working on a server which will provide service to a large number of mostly idle, low-bandwidth clients. we've use boost::asio as the basis for this, and so far it's working very well. We recently added SSL support, which was very straightforward and seamless. We're starting to look at the scalability of our SSL server, and are seeing some bottlenecks with memory usage. We're seeing about 50KB allocated for each SSL session, even when they are idle. That limits us to somewhat less than 40K users on our box with 2GB of RAM. Our non-SSL version takes about 10KB per user, and we can handle somewhat less than 200K users. Of this 50KB, it looks like 16KB of this is for the OpenSSL BIO object, possibly a bit more with OpenSSL's internal buffers. There is another 16KB buffer stored in the "impl" field of openssl_stream_service. The server is always waiting for data from the clients with an async_read_until, and that also creates a 16KB buffer in its openssl_operation buffer. That gets us up to 48KB of storage for the buffers of each idle connection. So, a few questions. First, does this seem about right? Am I reading the code correctly? Second, it looks like it's harmless to just make these buffers smaller, maybe 1KB, including the BIO buffer. Does that seem reasonable? Can anybody think of a problem with that approach I'm overlooking? I'm certainly no OpenSSL expert, so it's fairly likely... Third, is there a better way to do this? Most of boost::asio uses memory very efficiently, and I wonder if I'm doing something wrong to cause it to allocate all of this memory? Thanks for any thoughts or help! ----Scott.

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lambda code fails to compile on g++ 4.3.1
by Tim Hockin 17 Dec '08

17 Dec '08

This code builds and runs under g++ 4.2.2. It fails under 4.3.1. Help? Tim #include <boost/lambda/lambda.hpp> using boost::lambda::_1; template<typename Tcallback> void function(Tcallback callback) { (void)callback; } int main() { function(_1); // works function(_1+0); // fails return 0; } $ /usr/crosstool/v12/gcc-4.3.1-glibc-2.3.6-grte//i686-unknown-linux-gnu/bin/i686-unknown-linux-gnu-g++ -W -Wall -o broken broken.cc -I/usr/include /usr/include/boost/lambda/detail/lambda_functors.hpp: In instantiation of 'boost::lambda::lambda_functor<boost::lambda::identity<const int> >': /usr/include/boost/lambda/detail/lambda_functor_base.hpp:164: instantiated from 'boost::lambda::detail::deduce_argument_types_<boost::tuples::cons<const int, boost::tuples::null_type>, boost::tuples::null_type>' /usr/include/boost/lambda/detail/lambda_functor_base.hpp:170: instantiated from 'boost::lambda::detail::deduce_argument_types_<boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, const int, 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>' /usr/include/boost/lambda/detail/lambda_functor_base.hpp:213: instantiated from 'boost::lambda::detail::deduce_argument_types<boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, const int, 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>' /usr/include/boost/lambda/detail/operator_lambda_func_base.hpp:60: instantiated from 'boost::lambda::detail::binary_rt<boost::lambda::arithmetic_action<boost::lambda::plus_action>, boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, const int, 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>' /usr/include/boost/lambda/detail/operator_lambda_func_base.hpp:206: instantiated from 'boost::lambda::lambda_functor_base<boost::lambda::arithmetic_action<boost::lambda::plus_action>, boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, const int, 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> >::sig<boost::tuples::null_type>' /usr/include/boost/lambda/detail/lambda_functors.hpp:135: instantiated from 'boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::arithmetic_action<boost::lambda::plus_action>, boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, const int, 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> > >' broken.cc:14: instantiated from here /usr/include/boost/lambda/detail/lambda_functors.hpp:137: warning: type qualifiers ignored on function return type

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