March 2008 - Boost-users - lists.boost.org

boost::function "could not deduce template argument ..."
by Derrick Hathaway 07 Mar '08

07 Mar '08

I apologize if this isn't the sort of question this list is intended for, but if anyone could help me with my lack of sufficient template howto skill I would appreciate it. Essentially what I have is class template for boost::function1<bool, const ValueType &> like so: template <typename ValueType> class predicate { public: typedef boost::function1<bool, const ValueType&> type; struct and { bool operator()(const ValueType &)() { return left_() && right(); } type left_; type right_; }; struct or { ... }; }; And what I want is to overload the & and | operators for predicate<ValueType>::type like so: template <typename ValueType> typename predicate<ValueType>::type operator &( const typename predicate<ValueType>::type &left, const typename predicate<ValueType>::type &right) { return typename predicate<ValueType>::and(left, right); } The problem is when I compile I get the error message "could not deduce template argument for 'ValueType'" when I compile. Any idea what I'm doing wrong? I have attached example code. I am using MS Visual Studio 8, and boost 1.34.1. Thanks in advance. -Derrick

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automake + boost lib versions
by Klett, Stefan 07 Mar '08

07 Mar '08

Hi altogether, I've got a problem with rolling a packet to distribute a library source - first I tried to do this with boost-build , but later on I had some difficulties and fell back to automake. What I need is a (hopefully convenient) way to deal with different versions of the boost libraries - because I have to expect that the names of these libraries will differ on nearly all machines a potential User of "my" library is trying to build the source. For example the date-time lib appears as: /usr/local/lib/libboost_date_time-gcc42-1_34_1.a /usr/local/lib/libboost_date_time-gcc42-1_34_1.so /usr/local/lib/libboost_date_time-gcc42-1_34_1.so.1.34.1 /usr/local/lib/libboost_date_time-gcc42.a /usr/local/lib/libboost_date_time-gcc42-d-1_34_1.a /usr/local/lib/libboost_date_time-gcc42-d-1_34_1.so /usr/local/lib/libboost_date_time-gcc42-d-1_34_1.so.1.34.1 /usr/local/lib/libboost_date_time-gcc42-d.a /usr/local/lib/libboost_date_time-gcc42-d.so /usr/local/lib/libboost_date_time-gcc42-mt-1_34_1.a /usr/local/lib/libboost_date_time-gcc42-mt-1_34_1.so /usr/local/lib/libboost_date_time-gcc42-mt-1_34_1.so.1.34.1 /usr/local/lib/libboost_date_time-gcc42-mt.a /usr/local/lib/libboost_date_time-gcc42-mt-d-1_34_1.a /usr/local/lib/libboost_date_time-gcc42-mt-d-1_34_1.so /usr/local/lib/libboost_date_time-gcc42-mt-d-1_34_1.so.1.34.1 /usr/local/lib/libboost_date_time-gcc42-mt-d.a /usr/local/lib/libboost_date_time-gcc42-mt-d.so /usr/local/lib/libboost_date_time-gcc42-mt.so /usr/local/lib/libboost_date_time-gcc42.so in the case of my library using the multithreaded version is preferred. Hardwiring fails by the obvious reason that not everyone else is using gcc42 Is there anyone of you who has some experience in writing a proper configure.ac Makefile.am that is aware of these different boost-library names ? If so please give me a hint ... Thank you very much in advance Best regards Stefan -------------------------------------------------------- Stefan Klett (Dipl. Informatiker) | E-mail: stefan.klett(a)kit.edu Forschungszentrum Karlsruhe / KIT | Web: http://www.fzk.de SCC Steinbuch Centre for Computing| Phone: +49 (0)7247 828649 Hermann-von-Helmholtz-Platz 1 | Fax: +49 (0)7247 824972 D-76344 Eggenstein-Leopoldshafen | Mobile: +49 (0)176 20317250 -------------------------------------------------------------------

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Please help: Seg fault with threads
by Nishant Mittal 07 Mar '08

07 Mar '08

Hi All, I started on boost today and wrote my first hello world application. #include <boost/thread/thread.hpp> #include <iostream> using namespace std; void hello_world() { cout << "Hello world, I'm a thread!" << endl; } int main(int argc, char* argv[]) { boost::thread my_thread(&hello_world); my_thread.join(); return 0; } I compiled it using the command. g++ helloworld.cpp -lboost_thread-gcc41-mt-1_34_1 However, when I try to run it, I keep getting a segmentation fault. I tried to debug with gdb and this is what I get. (gdb) run Starting program: boost_test/a.out (no debugging symbols found) (no debugging symbols found) (no debugging symbols found) (no debugging symbols found) (no debugging symbols found) (no debugging symbols found) (no debugging symbols found) (no debugging symbols found) [Thread debugging using libthread_db enabled] [New Thread 46912498370912 (LWP 21199)] [New Thread 1084229952 (LWP 21202)] Program received signal SIGSEGV, Segmentation fault. [Switching to Thread 1084229952 (LWP 21202)] 0x00002aaaaaab4932 in boost::thread_group::add_thread () from /usr/local/lib/libboost_thread-gcc41-mt-1_34_1.so.1.34.1 (gdb) Please let me know as to what I am doing wrong. Any help is appreciated. Thanks Nishant

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[spirit] Segmentation fault when parsing grammar with threads
by Andreas Bruckmeier 07 Mar '08

07 Mar '08

Hi out there, after searching for the cause of segmentation faults in my program i figured out that it happens while parsing my grammar with spirit. But this happens only if i run multiple threads, with only one thread all works as expected. I used the current boost trunk, gcc 4.1.2 and option D_REENTRANT Does anybody have a clue what happens inside parse(...) that could cause this segfault? Best regards Andi calling code: ('buf' is a zero-terminated string) -------------------------------------------------------- HttpRequestGrammar parser; parse_info<const char*> parserInfo = parse(buf, parser); my grammar: (cutted some rules to limit length ;-)) -------------------------------------------------------- #ifndef BASIC_HTTP_GRAMMAR_H_ #define BASIC_HTTP_GRAMMAR_H_ #include <boost/spirit/core.hpp> #include <boost/spirit/actor/assign_actor.hpp> #include <boost/spirit/actor/insert_at_actor.hpp> using namespace boost::spirit; struct HttpRequestGrammar : public grammar<HttpRequestGrammar> { template <typename ScannerT> struct definition { definition(HttpRequestGrammar const& self) { first = ( request = *( SP | CRLF ) >> requestLine >> CRLF >> *(( generalHeader | requestHeader | entityHeader ) >> CRLF) >> CRLF, requestLine = method[insert_at_a(self.headerMap, "method")] >> SP >> requestUri[insert_at_a(self.headerMap, "url")] >> SP >> httpVersion[insert_at_a(self.headerMap, "version")], method = str_p("GET") | "HEAD", ... .. token = +graph_p, SP = str_p(" "), CRLF = str_p("\r\n") ); } subrule<0> request; subrule<1> requestLine; subrule<2> generalHeader; ... .. subrule<1000> SP; subrule<1001> CRLF; rule<ScannerT> first; rule<ScannerT> const& start() const { return first; } }; mutable std::map<std::string, std::string> headerMap; }; #endif /*BASIC_HTTP_GRAMMAR_H_*/

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Re: [Boost-users] [bind] Template deduction
by Robert Dailey 07 Mar '08

07 Mar '08

On Tue, Mar 4, 2008 at 7:16 PM, Marshall Clow <marshall(a)idio.com> wrote: > > Would this work? > std::for_each( myStrings.begin(), myStrings.end(), boost::bind( > &DoFoo<std::string>, 5, _1 ) ); Well, the example I gave was probably overly simple. The real example uses a boost::python::list, which can either take a char* or a std::string. At the time I'm doing the boost::bind, I do not know what type is being passed in.

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basename function in filesystem
by Alain Leblanc 07 Mar '08

07 Mar '08

Hi, Here's the description of the basename() function in the Filesystem library: template <class Path> typename Path::string_type basename(const Path & p); Returns: if p.leaf() contains a dot, returns the substring of p.leaf() starting at its beginning and ending at the last dot (the dot is not included). Otherwise, returns p.leaf() and if I run the following program ================================================== #include <string> #include <iostream> #include<boost/filesystem/operations.hpp> namespace bf = boost::filesystem; int main() { string name("/calvin/hobbes/xx.xml"); bf::path filepath(name); cerr << "Value for basename: " << basename(filepath.string().c_str()) << endl; } ================================================== I get as a result: Value for basename: xx.xml I seems like I should be getting 'xx'. Am I not understanding the description, or is there a problem with the library. a

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[boost.python] howto expose ptr_vector?
by Jörg Becker 06 Mar '08

06 Mar '08

Hello everyone. I have to expose a boost::ptr_vector. I'm wondering if I can use the indexing suite. But neither the docu nor google give me an answer. Are there any examples for the indexing_suite using a boost::ptr_vector or any other custom (non-stl) container? Thanks, Jörg

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[multi-index] question for a complex query
by Ovanes Markarian 06 Mar '08

06 Mar '08

Hello *, I currently need to implement the following use case and was wondering if this is possible with multi-index: I have a class, for simplicity all members are public wihtout accessors and mutators: class entry { public: field x; field y; filed z; }; I need a multi-index index to remember the order in which the elements were inserted and non uniquely index the inserted elements by hash of field x; Now a client could do the following queries: - get all entries in the order they were inserted (this is easy and I know how to do it) - get all entries which satisfy field x parameter in the order they were inserted. I know that I can retrieve the values dependent on hash(x), but these are probably not sorted. I know that I can project iterators, but can I project (range_retireved_via_hashed_X) to (range_retrieved_for_sequence_of_X) May be I miss smth here or should split my data in some other way to satisfy this condition. With Kind Regards, Ovanes Markarian

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Please help: Getting started with Boost
by Nishant Mittal 06 Mar '08

06 Mar '08

I have a 64 bit red hat linux (also 64 bit) box. 1) I downloaded boost from boost_1_34_1.tar.bz2 <http://downloads.sourceforge.net/boost/boost_1_34_1.tar.bz2?modtime=1185241 108&big_mirror=0> 2) Unizipped and installed it (./configure , make install ) everything worked fine. Questions: 1) How do I check if I now have the 64 bit version of boost? 2) I see that all libraries were put into /usr/local/lib and I can compile my hello world code with the following command. * $ g++ hello.cpp -lboost_thread-gcc41-mt-1_34_1 but when I try to run the created a.out file I get a file not found error msg. * $ ./a.out * ./a.out: error while loading shared libraries: libboost_thread-gcc41-mt-1_34_1.so.1.34.1: cannot open shared object file: No such file or directory I did an ldd and this is the output. $ ldd a.out libboost_thread-gcc41-mt-1_34_1.so.1.34.1 => not found libstdc++.so.6 => /usr/lib64/libstdc++.so.6 (0x0000003a6aa00000) libm.so.6 => /lib64/libm.so.6 (0x0000003a5a400000) libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x0000003a68600000) libc.so.6 => /lib64/libc.so.6 (0x0000003a5a000000) /lib64/ld-linux-x86-64.so.2 (0x0000003a59c00000) I am stuck and cannot make progress. I appreciate any help on this. Thanks Nishant

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[BGL] vertex_descriptors in STL containers
by Torsten Sadowski 06 Mar '08

06 Mar '08

Hi, I have written a program that works if I use vecS for the vertices and fails often with a crash when I use listS. vecS vertex descriptors are effectivly int so they pose no problem when used in std::set and std::map but listS vertex descriptors are of type void*. Could it be that comparison fails in the sets or could I have problems with a copy constructor somewhere? I know that STL is not designed to handle pointers but in my case the pointers could just be handled for their address value. The graph is not changed during my calculations. Cheers, Torsten

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