October 2007 - Boost-users - lists.preview.boost.org

[Serialization] Example for Boost.Any
by Joseph Lisee 15 Oct '07

15 Oct '07

Hello, 2 years ago on this list there was a discussion on how to serialize/deserialize a Boost.Any variable. I read through and found some proposals, but never any implementations. I was wondering whether anyone had ever gotten around to implementing it? I have no qualms about using a custom Boost.Any with serialization support coded in. -Joe

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what::runtime_error::std already defined
by Lars Schouw 15 Oct '07

15 Oct '07

I am getting these linking errors and can't figure out where it comes from. 4>libboost_regex-vc80-mt-gd-1_34_1.lib(instances.obj) : error LNK2005: "public: virtual char const * __thiscall std::runtime_error::what(void)const " (?what@runtime_error@std@@UBEPBDXZ) already defined in Curve.obj I am using Visual Studio 2005 SP1 and Windows XP Lars ____________________________________________________________________________________ Moody friends. Drama queens. Your life? Nope! - their life, your story. Play Sims Stories at Yahoo! Games. http://sims.yahoo.com/

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[program_options] Dynamic linking broken with VS7.1
by Robert Brueckmann 15 Oct '07

15 Oct '07

I tried to compile a simple test program, but it doesn't link dynamically. Any suggestions, what I'm doing wrong? I'm using boost 1.34.1 prebuilt libs from boost-consulting and MSVC 7.1. The test code which fails: #include <boost/program_options.hpp> namespace po = boost::program_options; int main(int argc, char** argv) { unsigned int i1; po::options_description normal_options("parameters"); normal_options.add_options() ("test,t", po::value<unsigned int>(&i1)->default_value(0), "test") ; return 0; } I compile using the following command: cl /TP /EHsc /nologo /GR /WL /W2 /Od /MDd /GS /Z7 /DBOOST_ALL_NO_LIB /Ih:\repos\trunk\3rd\include\common\boost\1_34_1 /c main.cpp /Fomain.obj The linker command link /nologo /OUT:test.exe /LIBPATH:h:\repos\trunk\3rd\lib\win32\cl\13.10\boost\1_34_1 boost_program_options-vc71-mt-gd-1_34_1.lib /DEBUG main.obj fails with the error message main.obj : error LNK2001: unresolved external symbol "class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > boost::program_options::arg" (?arg@program_options@boost@@3V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@A) However, when linking statically using link /nologo /OUT:test.exe /LIBPATH:h:\repos\trunk\3rd\lib\win32\cl\13.10\boost\1_34_1 libboost_program_options-vc71-mt-gd-1_34_1.lib /DEBUG main.obj then everything is working... Any ideas? Thank you in advance, Robert

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[Iostreams] stream not clearing state
by Benjamin Collins 14 Oct '07

14 Oct '07

I'm trying to use a stream and open/close the underlying device on the fly. Here's my test code: #include <iostream> #include <boost/filesystem.hpp> namespace fs = boost::filesystem; #include <boost/iostreams/device/mapped_file.hpp> #include <boost/iostreams/stream.hpp> namespace io = boost::iostreams; namespace { const uint32_t block_size = io::mapped_file_source::alignment(); } bool test1() { io::mapped_file_params mfp("rand.bin"); mfp.mode = std::ios_base::in | std::ios_base::binary; mfp.length = block_size; io::mapped_file mf(mfp); io::stream<io::mapped_file> in(mf); int blocks = fs::file_size("rand.bin")/block_size; if (fs::file_size("rand.bin") % block_size) ++blocks; for (int i=0;i<blocks;++i) { in->close(); mfp.offset = block_size*i; std::cout << "mapping bytes [" << block_size*i << " - " << block_size*(i+1) - 1 << "]\n"; in->open(mfp); in.clear(); std::cout << "stream is in state: [ "; if(in.rdstate() | std::ios::goodbit) std::cout << "good "; if(in.rdstate() | std::ios::badbit) std::cout << "bad "; if(in.rdstate() | std::ios::failbit) std::cout << "fail "; if(in.rdstate() | std::ios::eofbit) std::cout << "eof "; std::cout << "]\n"; int count=0; char x; while(!in.eof()) { if(io::stream<io::mapped_file>::traits_type::eof() == (x = in.get())) throw std::runtime_error("unexpected eof"); std::cout << '.'; ++count; } if(0==count) throw std::runtime_error("unable to read characters in this map"); else std::cout << count << "bytes read.\n"; } } If you don't like to see code in email, see here: http://pastebin.com/m40e9432b This program prints the following: ------------------------------------------------ mapping bytes [0 - 4095] stream is in state: [ bad fail eof ] terminate called after throwing an instance of 'std::runtime_error' what(): unexpected eof Aborted So what gives? Why isn't boost::iostreams::stream clearing its state properly? -- Benjamin A. Collins <ben.collins(a)acm.org> http://bloggoergosum.us

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[BGL] Inverse property mapping?
by "Alejandro M. Aragón" 14 Oct '07

14 Oct '07

Hello everyone, I've been looking for some time at the documentation and I couldn't find a single way to obtain an inverse mapping for a property map. That is, given a property p, I would like to obtain a vertex descriptor v. It seems that the mapping is only in one direction. Is there a way to obtain the inverse mapping too? If so, what is the complexity associated with obtaining the vertex descriptor? Thank you, a²

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[serialization]-- boost integrated with MFC Doc/View?
by Rich Peters 13 Oct '07

13 Oct '07

I am looking at boost serialization and it looks very good. Has anyone tried to integrate boost serialization with MFC Doc/View CArchive serialization? I would be interested to hear how you did it. Can a CArchive be turned into a istream or ostream that could be used? thanks

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ptr_set problems
by Surya Kiran Gullapalli 13 Oct '07

13 Oct '07

Hello, I'm using ptr_set for one of my classes whose structure is like this. =============================== using namespace boost; class A: less_than_comparable<A>, equality_comparable<B>, noncopyable { friend operator< (const A&, const A&) ; public: A() virtual ~A () virtual void fun1() = 0 ; } class B: public A { public: B () ; ~B () ; virtual void fun1() { cout << "Func1 in B" << endl ; } } class C : public A { public: C () ; ~C () ; virtual void fun1() { cout << "Func1 in C" << endl ; } } ============================================== and I'm inserting into ptr_set like this. A *varb = new B () ; A *varc = new C() ; ptr_set <A> Aset ; Aset.insert (varb) ; Aset.insert (varc) ; **************** Compilation is fine on windows (VS2005) and linux (gcc-4.1.2) On linux, the code executes fine. But on windows, I'm getting a DEBUG ASSERTION failure during insertion. The failure says, Expression: invalid operator<. This happens in debug version only. In release version, the code executes fine on windows also. Any help on how to attack this problem is greatly appreciated. Thanks in advance, Surya

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Making an ordinary function into something useful in lambda expressions
by Peter Waller 13 Oct '07

13 Oct '07

I wish to write some lambda functions to have this sort of behaviour. #include <lambda/lambda.hpp> #include <lambda/bind.hpp> #include <function.hpp> using namespace boost::lambda; using namespace boost; #include <iostream> using std::cout; using std::endl; #include <cmath> int main( int argc, char *argv[] ) { float value; var_type<float>::type theValue( var( value ) ); // Ignore this line #define cos(theta) bind( unlambda(bind( cos, _1 )), theta ) function<float ( float )> myfunction = ( cos( theValue ) - 1 ); value = 2; cout << "The result = " << myfunction(1) << endl; return 0; } Namely, the cos( value ) part. The code above works, but I feel that using a #define is a little messy, and seems hard to generalise to functions with more arguments. I was wondering if there was a general, better way of turning a given function into one whose execution is delayed. Thanks in advance, - Peter

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[boost-users][function, assign] error C2986 and C2784 on visual studio 2005 .
by chun ping wang 13 Oct '07

13 Oct '07

So given this header. template < QSTYPE type, typename T, template <typename ELEM, typename = std::allocator<ELEM> > class CONT > CONT<T> quicksort(CONT<T>); // inside the main file. // I decided a function that takes vector of integer and returns a vector of integer. typedef boost::function<std::vector<int>(std::vector<int>)> sortfunc; // create a function list to hold the sorting function. // bunch of number include. #include <boost/assign/std/vector.hpp> std::vector<sortfunc> function_list; using boost::assign::operator+=; std::vector<sortfunc> function_list; // quicksort random function_list += (&algocpw::quicksort<algocpw::QSTYPE(algocpw::RANDOM), int, std::vector>), // quicksort median (&algocpw::quicksort<algocpw::QSTYPE(algocpw::MEDIAN), int, std::vector>), // quicksort mediantriple (&algocpw::quicksort<algocpw::QSTYPE(algocpw::MEDIANTRIPLE), int, std::vector>), // merge sort (&algocpw::mergesort<int, std::vector>), // heap sort (&algocpw::heapsort<int, std::vector>), // selection sort (&algocpw::selection_sort<int, std::vector>), // standard sort (&algocpw::standard_sort<int, std::vector>); I get the following errors. ./cs512/c++/sortingMain.cpp(63) : error C2896: 'boost::assign::list_inserter<boost::assign_detail::call_push_back<std::vector<_Ty,_Alloc>>,V> boost::assign::operator +=(std::vector<_Ty,_Alloc> &,V2)' : cannot use function template 'CONT<T> algocpw::mergesort(CONT<T>)' as a function argument c:\cpw\msvc\cs512\c++\def\../sortingAlgo.hpp(32) : see declaration of 'algocpw::mergesort' ./cs512/c++/sortingMain.cpp(63) : error C2784: 'boost::assign::list_inserter<boost::assign_detail::call_push_back<std::deque<T,Allocator>>,V> boost::assign::operator +=(std::deque<T,Allocator> &,V2)' : could not deduce template argument for 'std::deque<T,Allocator> &' from 'std::vector<_Ty>' with [ _Ty=sortfunc ] Where did "deque" come from.. i never included deque.

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[ANN] Xpressive 2.0.0
by Eric Niebler 12 Oct '07

12 Oct '07

Xpressive has just reached 2.0! The new version has lots of cool new features (see below). Subversion and the File Vault both have the latest code. It works with HEAD and with Boost v1.34.1. Below is an earlier message announcing the feature set of xpressive 2.0. The latest docs are here: http://boost-sandbox.sourceforge.net/libs/xpressive/doc/html/index.html Also, xpressive.zip in the File Vault (Strings - Text Processing directory) contains the docs in pdf format. Please grab the latest code and let me know of any problems you encounter so I can get them fixed for 1.35. -- Eric Niebler Boost Consulting www.boost-consulting.com Eric Niebler wrote: > It's a poorly kept secret that I've been adding new features to > Xpressive on CVS HEAD for a while now. So here are the features already > implemented (documentation forthcoming) for Xpressive 2.0: > > << Semantic Actions >> > > Specify code to execute when parts of a regex match, a-la Spirit's > semantic actions. Eg.: if you want to parse a string of name/value pairs > into a std::map, you might: > > std::map<std::string, int> result; > std::string str("aaa=>1 bbb=>23 ccc=>456"); > > // Like "(\\w+)=>(\\d+)": > sregex pair = ( (s1= +_w) >> "=>" >> (s2= +_d) ) > [ ref(result)[s1] = as<int>(s2) ]; > sregex rx = pair >> *(+_s >> pair); > > if(regex_match(str, rx)) > { > assert(result["aaa"] == 1); > assert(result["bbb"] == 23); > assert(result["ccc"] == 456); > } > > The actions are placed on a queue and executed in order only when the > regex match succeeds. > > << Custom Assertions >> > > Use the check() function to create a boolean predicate that can > participate in the match. Here's a regex that recognizes two integers > only if the first is less than the second: > > sregex rx = ( (s1= +_d) >> ' ' >> (s2= +_d) ) > [ check( as<int>(s1) < as<int>(s2) ) ]; > > Unlike actions, predicates execute immediately. You can also define the > predicate out-of-line as a function object. > > << Dynamic Regex Grammars with Named Regexes >> > > Using regex_compiler, you can map a name to a regex object, and then > refer to that regex from another by name. In this way, you can build > grammars from regexes at runtime. > > sregex_compiler comp; > sregex rx = comp.compile("^bar(?$RE)baz$"); > comp.compile("(?$RE=)\\d+ \\d+"); > > There's an alternate syntax for associating a name with a regex that you > can use to nest a static regex in a dynamic one. Eg., the last line > above could be: > > comp["RE"] = +_d >> ' ' >> +_d; > > With these changes, you can now nest static and dynamic regexes within > each other freely, giving you lots of flexibility to build grammars and > modify them on the fly. > > << Named Captures >> > > For dynamic regular expressions, you can create a named capture with > (?P<name> ...). You can refer back to the named capture with (?P=name). > In substitution strings (for use with regex_replace()), you can refer > back to a named capture with \\g<name> when using the format_perl or > format_all flags. > > And more .... I'd like to give props to Dave Jenkins who has been doing > m4d things with this stuff already, and who has given me a laundry list > of other features he'd like.

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