- Boost-users - lists.boost.org

[hash] Performance & distribution, variable bit width
by Sebastian Karlsson 14 Mar '11

14 Mar '11

As I use boost::hash quite a bit I have a few questions which the documentation seems to leave out. First of all it would be terrific if there was a performance & distribution benchmark as a part of the documentation to make it easier to evaluate the merits of using it. Secondly I'm a bit stumped on why the return value is fixed to size_t for a couple of reasons. Bit width of size_t isn't guaranteed to be constant, wouldn't this severely affect the distribution properties of the hashing algorithm used? Furthermore it would be great if the user could choose the bit width of the hash. Often the birthday problem is relevant, and being able to swap to using a 64 bit hash easily is something that doesn't seem possible but often desirable. Kind regards, Sebastian Karlsson

1 0

punits][accumulators] buggy behavior for min accumulator of quantities
by alfC 14 Mar '11

14 Mar '11

Hi, Sometimes it is difficult to make boost::units quantities with other libraries. For example to have boost::accumulators mean work with units, one has to specialize division by integer for quantities. In this example the accumulators and units compiles out of the box but gives an incorrect answer. #include<boost/accumulators/accumulators.hpp> #include <boost/accumulators/statistics/min.hpp> // or other stat features #include <boost/accumulators/statistics/max.hpp> // or other stat features #include<boost/units/systems/si.hpp> #include<boost/units/io.hpp> using namespace boost::accumulators; using namespace boost::units; int main(){ accumulator_set<quantity<si::time>, features<tag::min, tag::max> > a; a(2.1*si::second); a(2.0*si::second); a(4.1*si::second); std::cout << extract::min(a)<< " " << extract::max(a)<< std::endl ; return 0; } It prints: 0 s 4.1 s instead of: 2.1 s 4.1 s So, it seems that the min extractor fails for quantities. I would like to know if there is a way to correctly specialize "min" for quantities. (By the way, std::min for quantities works fine). However the behavior is unfortunate in the first place. Regardless of the solution I would label this as a bug of one of the two libraries. Thank you, Alfredo

2 3

Preventing iostreams from accessing freed memory
by Adam Nielsen 14 Mar '11

14 Mar '11

Hi all, I'm unable to prevent Boost iostreams from accessing memory once it has been freed, and I'm hoping someone here familiar with iostreams has some advice. As far as I can tell, when I push a standard iostream onto a filter, the filter holds on to a reference of it. If this happens inside a function, then when the function returns the iostream is freed, followed by the filter. In its destructor the filter tries to perform a flush/close and promptly segfaults, as it is trying to access the iostream which has just been freed. There is a set_auto_close() function I can call on the filter which sounds like it would do the trick, but it doesn't and according to the docs it's because it "does not prevent the Filters and Devices in the chain from being closed [flushed] automatically if the chain is complete at destruction." So is there any way I can prevent a filtering_stream from performing I/O in its destructor? Thanks, Adam.

1 1

[property tree][json]how to create empty array?
by Kulti 12 Mar '11

12 Mar '11

Hi, all! It's possible to get following output from boost::property_tree::json_parser::write_json ? { "id": "id", "method": "test_method", "params": [] } I know how to create array with some items, but when I try to create empty array, I've get "params": ""

3 3

temporary filenames
by Kraus Philipp 12 Mar '11

12 Mar '11

Hello, is there any implementation for creating temporary files names? I'm using tmpnam, but it can be dangerous. On posix systems I can use mkstemp. Is there any save implementation within the boost (perhaps in the iostreams)? Thanks Phil

2 2

boost-users@lists.boost.org
by Stephen Hewitt 12 Mar '11

12 Mar '11

I have recently upgraded to Boost 1.46 and am having trouble compiling the following simple program (Using Visual Studio 2005): // Error.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include <tchar.h> #include <iostream> #include <boost/property_tree/ptree.hpp> #include <boost/property_tree/json_parser.hpp> void Go() { boost::property_tree::ptree t; boost::property_tree::read_json(std::cin, t); } int _tmain(int argc, _TCHAR* argv[]) { Go(); return 0; } Here are the errors I get: 1>------ Build started: Project: Error, Configuration: Debug Win32 ------ 1>Compiling... 1>stdafx.cpp 1>Compiling... 1>Error.cpp 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(184) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1> c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(178) : while compiling class template member function 'boost::property_tree::json_parser::json_grammar<Ptree>::definition<Scanner>::definition(const boost::property_tree::json_parser::json_grammar<Ptree> &)' 1> with 1> [ 1> Ptree=boost::property_tree::ptree, 1> Scanner=scanner_t 1> ] 1> c:\libraries\boost_1_46_0\boost\spirit\home\classic\core\non_terminal\impl\grammar.ipp(279) : see reference to class template instantiation 'boost::property_tree::json_parser::json_grammar<Ptree>::definition<Scanner>' being compiled 1> with 1> [ 1> Ptree=boost::property_tree::ptree, 1> Scanner=scanner_t 1> ] 1> c:\libraries\boost_1_46_0\boost\spirit\home\classic\core\non_terminal\impl\grammar.ipp(298) : see reference to function template instantiation 'void boost::spirit::classic::impl::call_helper<0>::do_<result_t,definition_t,ScannerT>(RT &,DefinitionT &,const ScannerT &)' being compiled 1> with 1> [ 1> ScannerT=scanner_t, 1> RT=result_t, 1> DefinitionT=definition_t 1> ] 1> c:\libraries\boost_1_46_0\boost\spirit\home\classic\core\non_terminal\grammar.hpp(55) : see reference to function template instantiation 'boost::spirit::classic::match<boost::spirit::classic::nil_t> boost::spirit::classic::impl::grammar_parser_parse<0,boost::property_tree::json_parser::json_grammar<Ptree>,boost::spirit::classic::parser_context<>,ScannerT>(const boost::spirit::classic::grammar<DerivedT> *,const ScannerT &)' being compiled 1> with 1> [ 1> Ptree=boost::property_tree::ptree, 1> ScannerT=scanner_t, 1> DerivedT=boost::property_tree::json_parser::json_grammar<boost::property_tree::ptree> 1> ] 1> c:\libraries\boost_1_46_0\boost\spirit\home\classic\core\non_terminal\grammar.hpp(65) : see reference to function template instantiation 'boost::spirit::classic::match<boost::spirit::classic::nil_t> boost::spirit::classic::grammar<DerivedT>::parse_main<ScannerT>(const ScannerT &) const' being compiled 1> with 1> [ 1> DerivedT=boost::property_tree::json_parser::json_grammar<boost::property_tree::ptree>, 1> ScannerT=scanner_t 1> ] 1> c:\libraries\boost_1_46_0\boost\spirit\home\classic\core\scanner\impl\skipper.ipp(109) : see reference to function template instantiation 'boost::spirit::classic::match<boost::spirit::classic::nil_t> boost::spirit::classic::grammar<DerivedT>::parse<scanner_t>(const ScannerT &) const' being compiled 1> with 1> [ 1> DerivedT=boost::property_tree::json_parser::json_grammar<boost::property_tree::ptree>, 1> ScannerT=scanner_t 1> ] 1> c:\libraries\boost_1_46_0\boost\spirit\home\classic\core\scanner\impl\skipper.ipp(155) : see reference to function template instantiation 'boost::spirit::classic::parse_info<IteratorT> boost::spirit::classic::impl::phrase_parser<SkipT>::parse<IteratorT,DerivedT>(const IteratorT &,const IteratorT &,const ParserT &,const SkipT &)' being compiled 1> with 1> [ 1> IteratorT=It, 1> SkipT=boost::spirit::classic::alternative<boost::spirit::classic::alternative<boost::spirit::classic::space_parser,boost::spirit::classic::confix_parser<boost::spirit::classic::impl::string_as_parser::type,boost::spirit::classic::kleene_star<boost::spirit::classic::anychar_parser>,boost::spirit::classic::alternative<boost::spirit::classic::eol_parser,boost::spirit::classic::end_parser>,boost::spirit::classic::unary_parser_category,boost::spirit::classic::non_nested,boost::spirit::classic::is_lexeme>>,boost::spirit::classic::confix_parser<boost::spirit::classic::impl::string_as_parser::type,boost::spirit::classic::kleene_star<boost::spirit::classic::anychar_parser>,boost::spirit::classic::impl::string_as_parser::type,boost::spirit::classic::unary_parser_category,boost::spirit::classic::non_nested,boost::spirit::classic::is_lexeme>>, 1> DerivedT=boost::property_tree::json_parser::json_grammar<boost::property_tree::ptree>, 1> ParserT=boost::property_tree::json_parser::json_grammar<boost::property_tree::ptree> 1> ] 1> c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(312) : see reference to function template instantiation 'boost::spirit::classic::parse_info<IteratorT> boost::spirit::classic::parse<std::_Vector_iterator<_Ty,_Alloc>,DerivedT,boost::spirit::classic::alternative<A,B>>(const IteratorT &,const IteratorT &,const boost::spirit::classic::parser<DerivedT> &,const boost::spirit::classic::parser<boost::spirit::classic::alternative<A,B>> &)' being compiled 1> with 1> [ 1> IteratorT=It, 1> _Ty=Ch, 1> _Alloc=std::allocator<char>, 1> DerivedT=boost::property_tree::json_parser::json_grammar<boost::property_tree::ptree>, 1> A=boost::spirit::classic::alternative<boost::spirit::classic::space_parser,boost::spirit::classic::confix_parser<boost::spirit::classic::impl::string_as_parser::type,boost::spirit::classic::kleene_star<boost::spirit::classic::anychar_parser>,boost::spirit::classic::alternative<boost::spirit::classic::eol_parser,boost::spirit::classic::end_parser>,boost::spirit::classic::unary_parser_category,boost::spirit::classic::non_nested,boost::spirit::classic::is_lexeme>>, 1> B=boost::spirit::classic::confix_parser<boost::spirit::classic::impl::string_as_parser::type,boost::spirit::classic::kleene_star<boost::spirit::classic::anychar_parser>,boost::spirit::classic::impl::string_as_parser::type,boost::spirit::classic::unary_parser_category,boost::spirit::classic::non_nested,boost::spirit::classic::is_lexeme> 1> ] 1> c:\libraries\boost_1_46_0\boost\property_tree\json_parser.hpp(45) : see reference to function template instantiation 'void boost::property_tree::json_parser::read_json_internal<Ptree>(std::basic_istream<_Elem,_Traits> &,Ptree &,const std::string &)' being compiled 1> with 1> [ 1> Ptree=boost::property_tree::ptree, 1> _Elem=char, 1> _Traits=std::char_traits<char> 1> ] 1> c:\users\steve\documents\visual studio 2005\projects\error\error.cpp(13) : see reference to function template instantiation 'void boost::property_tree::json_parser::read_json<boost::property_tree::ptree>(std::basic_istream<_Elem,_Traits> &,Ptree &)' being compiled 1> with 1> [ 1> _Elem=char, 1> _Traits=std::char_traits<char>, 1> Ptree=boost::property_tree::ptree 1> ] 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(184) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(184) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(184) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(184) : error C2882: 'assertion' : illegal use of namespace identifier in expression 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(184) : error C3861: 'expect_object': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(185) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(185) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(185) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(185) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(185) : error C2882: 'assertion' : illegal use of namespace identifier in expression 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(185) : error C3861: 'expect_eoi': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(186) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(186) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(186) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(186) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(186) : error C2882: 'assertion' : illegal use of namespace identifier in expression 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(186) : error C3861: 'expect_objclose': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(187) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(187) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(187) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(187) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(187) : error C2882: 'assertion' : illegal use of namespace identifier in expression 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(187) : error C3861: 'expect_arrclose': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(188) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(188) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(188) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(188) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(188) : error C2882: 'assertion' : illegal use of namespace identifier in expression 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(188) : error C3861: 'expect_name': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(189) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(189) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(189) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(189) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(189) : error C2882: 'assertion' : illegal use of namespace identifier in expression 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(189) : error C3861: 'expect_colon': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(190) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(190) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(190) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(190) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(190) : error C2882: 'assertion' : illegal use of namespace identifier in expression 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(190) : error C3861: 'expect_value': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(191) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(191) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(191) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(191) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(191) : error C2882: 'assertion' : illegal use of namespace identifier in expression 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(191) : error C3861: 'expect_escape': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(195) : error C3861: 'expect_object': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(196) : error C3861: 'expect_eoi': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(203) : error C3861: 'expect_objclose': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(209) : error C3861: 'expect_name': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(210) : error C3861: 'expect_colon': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(211) : error C3861: 'expect_value': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(218) : error C3861: 'expect_arrclose': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(224) : error C3861: 'expect_value': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(250) : error C3861: 'expect_escape': identifier not found 1>Build log was saved at "file://c:\Users\Steve\Documents\Visual Studio 2005\Projects\Error\Debug\BuildLog.htm" 1>Error - 57 error(s), 0 warning(s) ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

2 1

lambda : fabs( x - y )< eps
by er 12 Mar '11

12 Mar '11

I'm submitting this in case someone easily spots a less verbose representation of fabs( x - y )< eps than the one shown below and would like to share it. Using lambda (or variants) only (I know I can write my own functor class). Thanks. #include <cmath> #include <boost/function.hpp> #include <boost/lambda/bind.hpp> #include <boost/lambda/lambda.hpp> #include <boost/numeric/conversion/bounds.hpp> typedef boost::function<double(double)> f1_; typedef boost::function<double(double, double)> f2_; typedef boost::function<bool(double)> g_; double eps = boost::numeric::bounds<double>::smallest(); f2_ f2 = lambda::bind( f1_( fabs ), lambda::_1 - lambda::_2 ) ; g_ g = ( eps > lambda::_1 ); BOOST_ASSERT( lambda::bind( g, lambda::bind( f2, lambda::_1, lambda::_2 ) )( 0.0, 0 * eps ) ); BOOST_ASSERT( !lambda::bind( g, lambda::bind( f2, lambda::_1, lambda::_2 ) )( 0.0, eps ) );

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[range] strange behaviour with range-based for loop and adaptors
by Nathan Ridge 12 Mar '11

12 Mar '11

Hello, I am experiencing some strange behaviour when using adaptors with a range-based for loop. Here's what I'm trying: #include <vector> #include <iostream> #include <boost/foreach.hpp> #include <boost/range/adaptor/transformed.hpp> std::vector<int> f() { return std::vector<int>{1, 2, 3, 4}; } int add1(int x) { return x + 1; } int main() { for (int i : f() | boost::adaptors::transformed(add1)) std::cout << i << ' '; std::cout << '\n'; } The output is 1 3 4 5, instead of the 2 3 4 5 that I would expect. Is there something funny going on with temporaries? Does the temporary returned by f() not stick around for the duration of the loop? Thanks, Nate.

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cyl_bessel_j performance
by Matwey V. Kornilov 12 Mar '11

12 Mar '11

Hi, cyl_bessel_j is several times slower than jn from glibc for me. What do I do wrong? Bessel function from boost.math seems to be pretty good coded and optimized but in a runtime it baffles me.

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[proto] Object got sliced when passed by reference
by Leon Sit 12 Mar '11

12 Mar '11

Hi all I have a class tree as the following template<typename T> struct base{ bool operator()(int i)const { return static_cast< const T&>(*this)(i); } }; struct F1:public base<F1>{ bool operator()(int i) const{ return true; } }; struct F2:public base<F2>{ bool operator()(int i) const{ return true; } }; struct F3 :public base<F3>{ std::string junk_; F3(std::string junk):junk_(junk){} bool operator()(int i) const{ std::cout << junk_ << std::endl; return false; } }; ================================================================== I am trying to use proto to derive the following systax Predicate<F1> f1; Predicate<F2> f2; Predicate<F3> f3("hodqhoqw"); cout << ((f1||f2)&&f3)(1) << endl; ================================================================== When proto get to the point of invoking the F3::operator(), the junk_ attribute got sliced away. I thought I am passing everything by constant reference but the exception tells me otherwise. The full sample code is attached, can someone tell me what I have missed? I am testing my code on vc9 and vc10, and I am not using virtual function for performance issue. Ultimately, I want to have the following syntax in the client code F1 f1; F2 f2; F3 f3("hodqhoqw"); cout << ((f1||f2)&&f3)(1) << endl; Thanks

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