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

Boost::bind member function and save to function pointer
by David McCallum 14 Apr '11

14 Apr '11

I'd like to implement an event-handling scheme that supports member functions. For example, I would have a class that accepts a function pointer, stores it, and calls that function when some event occurs. I'd like to be able to store a pointer to a member function with boost::bind(): void staticReceiver(std::string message) { cout << message << endl; }//staticReceiver void ChatClient::memberReceiver(std::string message) { cout << message << endl; }//testReceiver void ChatClient::testBind(void) { void (*funcPointer)(std::string message); boost::bind(&ChatClient::memberReceiver, this, _1)("Bind works"); funcPointer = staticReceiver; (*funcPointer) ("Function pointer works"); //##### THIS LINE WILL NOT COMPILE ##### funcPointer = boost::bind(&ChatClient::memberReceiver, this, _1); }//testBind However, I get the following compiler error: g++ -DHAVE_CONFIG_H -I. -I./libdasyne/lowlevel -I/opt/boost/include -D_REENTRANT -Wall -g -O2 -MT ChatClient.o -MD -MP -MF .deps/ChatClient.Tpo -c -o ChatClient.o `test -f 'examples/ChatClient.cpp' || echo './'`examples/ChatClient.cpp examples/ChatClient.cpp: In member function ‘void ChatClient::testBind()’: examples/ChatClient.cpp:56: error: cannot convert ‘boost::_bi::bind_t<void, boost::_mfi::mf1<void, ChatClient, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, boost::_bi::list2<boost::_bi::value<ChatClient*>, boost::arg<1> > >’ to ‘void (*)(std::string)’ in assignment make: *** [ChatClient.o] Error 1 Can it be done? Thanks in advance.

5 5

[phoenix] v2 to v3 transition of extension mechanism
by alfC 14 Apr '11

14 Apr '11

Hi, I am updating some of my code to use Phoenix3 instead of Phoenix2. For example in Phoenix2 I used to have this extension to support 'cos(...)' expressions: namespace boost{ namespace phoenix{ struct cos_eval{ template<class Env, typename Arg_> struct result{typedef double type;}; template<class RT, typename Env, typename Arg_> static RT eval(Env const& env, Arg_ const& arg_){ return cos(arg_.eval(env)); } }; template<typename Arg_> void cos(Arg_ const& arg_){ return compose<cos_eval>(arg_); } }} In Phoenix3, if I followed things correctly (from here https://svn.boost.org/svn/boost/sandbox/SOC/2010/phoenix3/libs/phoenix/doc/…) the new framework ask for the following, which doesn't work. The error (see at end) is difficult to decipher. What am I missing to implement this simple expression extension? -- Thanks. #include<boost/phoenix/phoenix.hpp> //v3 BOOST_PHOENIX_DEFINE_EXPRESSION( (boost)(phoenix)(cos_) , (meta_grammar) // Arg ) namespace boost { namespace phoenix { struct cos_eval{ typedef double result_type; template <typename Context, typename Arg> result_type operator()(Context const& ctx, Arg const& arg) const{ return std::cos(eval(arg, ctx)); } }; template <typename Dummy> struct default_actions::when<rule::cos_, Dummy> : call<cos_eval, Dummy> {}; template <typename Arg> typename expression::cos_<Arg>::type const cos_(Arg const& arg){ return expression::cos_<Arg>::make(arg); } }} usr/include/boost/proto/matches.hpp:846:13: error: no type named ‘proto_tag’ in ‘const struct boost::phoenix::vector2<boost::phoenix::vector2<const boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::phoenix::tag::cos_, boost::proto::argsns_::list1<boost::phoenix::actor<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<boost::phoenix::argument<1> >, 0l> > >, 1l> >*, double&>&, const boost::phoenix::default_actions&>’ compilation terminated due to -Wfatal-errors.

3 7

[phoenix] Basic recursive function.
by Robert Jones 14 Apr '11

14 Apr '11

I'm a newbie to Phoenix, just exploring, but I guess my intent in this code is obvious. Can anyone tell me what I'm doing wrong? Thx - Rob. #include <iostream> #include <boost/spirit/include/phoenix_core.hpp> #include <boost/spirit/home/phoenix/operator.hpp> #include <boost/spirit/home/phoenix/statement.hpp> #include <boost/function.hpp> using namespace boost::phoenix; using namespace boost::phoenix::arg_names; using namespace std; int main() { boost::function<unsigned( unsigned )> factorial; factorial = if_else( _1 == 0, 1, _1 * factorial( _1 - 1 ) ); cout << factorial( 3 ) << endl; return 0; }

3 4

run time error for min_max_paths.cpp of Graph Library 1.46.1 on Fedora 12
by albert kao 14 Apr '11

14 Apr '11

I compiled the min_max_paths.cpp in the example directory of BGL 1.46.1 on Fedora 12. $ g++ -I ~/boost_1_46_1 min_max_paths.cpp -o min_max_paths \ -L ~/boost_1_46_1_build/boost/bin.v2/libs/graph/build/gcc-4.4.4/release/link-static/threading-multi/ -lboost_graph Please help to solve the following run time error. $ min_max_paths terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::negative_edge> >' what(): The graph may not contain an edge with negative weight. Aborted (core dumped) My configuration is as follows: $ uname -a Linux triplecore 2.6.31.5-127.fc12.i686 #1 SMP Sat Nov 7 21:41:45 EST 2009 i686 athlon i386 GNU/Linux $ g++ -v Using built-in specs. Target: i686-redhat-linux Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla--enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --enable-plugin --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --enable-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib --with-ppl --with-cloog --with-tune=generic --with-arch=i686 --build=i686-redhat-linux Thread model: posix gcc version 4.4.4 20100630 (Red Hat 4.4.4-10) (GCC)

2 1

[format] Reuse of the format object
by Maxime van Noppen 14 Apr '11

14 Apr '11

Hi, I've got a question about the reuse of the boost::format object. Given this minimal testcase: ----------------------------------------------------------- #include <iostream> #include <boost/format.hpp> int main() { boost::format fmt("%|=12| %|=12| %|=12|\n"); // 1 std::cout << boost::str(fmt % "a" % "b" % "c") << boost::str(fmt % 1 % 2 % 3); // 2 std::cout << fmt % "a" % "b" % "c" << fmt % 1 % 2 % 3; } ----------------------------------------------------------- Why is 1 working while 2 produces the runtime exception: > terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::io::too_many_args> >' > what(): boost::too_many_args: format-string referred to less arguments than were passed ? I didn't find an explanation about this in the doc & the example about the reuse of format objects here: http://www.boost.org/doc/libs/1_46_1/libs/format/example/sample_advanced.cpp Using boost 1.46.0 and g++ 4.5.2. Thanks, -- Maxime

3 5

Re: [Boost-users] Boost::bind member function and save to function pointer
by justin allen 14 Apr '11

14 Apr '11

you probably really do want to look into an event system that will prescribe a bit of pre-built organization but if you just want to store the bind for later boost function will do it. http://www.boost.org/doc/libs/1_46_1/doc/html/function.html #include <boost/bind.hpp> #include <boost/function.hpp> #include <iostream> boost::function<void (std::string)> func; class Object { void runner(std::string message) { std::cout << message << std::endl; } public: void assign() { func = boost::bind(&Object::runner, this, _1); } }; int main(int argc, char **argv) { Object obj; obj.assign(); func("my message"); return 0; }

1 0

[filesystem] std::bad_alloc during dll initialization when migrating to filesystem v3
by Richard Ulrich 13 Apr '11

13 Apr '11

Hi Guys, I'm currently migrating our system consisting of multiple dll's and and executable to filesystem v3. The first two dll's that use boost::filesystem load ok, but the third fails with std::bad_alloc in the locale copy constructor called from default_locale during the construction of dot_path. I don't know if it's relevant, but we usually work with char while filesystem uses wchar_t for BOOST_WINDOWS_API Rgds Richard

1 0

Intrusive
by asif saeed 13 Apr '11

13 Apr '11

Hi, I frequently come across the term "intrusive" in boost users mailing list. What does it mean? Would any of you please provide a reference such as an online reference/link, etc? TIA, Asif

3 2

Writing large binary files with boost gzip
by Anders Knudby 13 Apr '11

13 Apr '11

Hello all, please help! I'm truly banging my head against the wall here. I am trying to write a function that will allow me to write gzipped binary files (~50 MB) and read them again. I have data in memory. Here's my code for writing: namespace io = boost::iostreams; filename = "c:/test.bin.gz"; //My output file int size = 5000000; //Data size in bytes, ~5 MB //Create filtering_ostream io::filtering_ostream out; //Creates a filtering_ostream called out out.push(io::gzip_compressor()); //Assigns the gzip_compressor to out out.push(io::file_sink(filename)); //Assigns a file sink to out char* memblock = new char [size]; //This is my data. In reality memblock will have been created earlier and filled with real data out.write(memblock, size); //Do the writing delete[] memblock; //Clean up As written above the resulting file, c:/test.bin.gz, is corrupt. If I try to decompress it, either with gzip or winrar, I get an error message. However, if I instead set size = 4000000 (~4 MB) (slightly smaller), the resulting file works just fine. My problem therefore is that my actual size is 50 MB... Please help! Anders (not a real programmer)

4 6

[Floating Point Utilities] where is the "nonfinite_num_facets.hpp"
by François Mauger 13 Apr '11

13 Apr '11

Hi As far as I understood, the Floating Point Utilities vault contribution by Johan R°ade has been integrated in the Boost official release. I've been using the "nonfinite_num_facets.hpp" header file for a few years within old Boost versions, directly extracted from the vault ZIP file released by Johan. Now, I can use the "fpclassify.hpp" file directly from the "boost/spirit/home/support/detail/math/" directory. Unfortunately I cannot find the "nonfinite_num_facets.hpp" file. Where can I find the "nonfinite_num_put/get" template class in say Boost 1.44 ? Maybe it has not been renamed in some other file or even not accepted at all... It is very useful for making my text and xml archives protable with NaNs and infinity support. Thanks for any hint or help. frc -- François Mauger Groupe "Interactions Fondamentales et Nature du Neutrino" NEMO-3/SuperNEMO Collaboration LPC Caen-CNRS/IN2P3-UCBN-ENSICAEN Département de Physique -- Université de Caen Basse-Normandie Adresse/address: Laboratoire de Physique Corpusculaire de Caen (UMR 6534) ENSICAEN 6, Boulevard du Marechal Juin 14050 CAEN Cedex FRANCE Courriel/e-mail: mauger(a)lpccaen.in2p3.fr Tél./phone: 02 31 45 25 12 / (+33) 2 31 45 25 12 Fax: 02 31 45 25 49 / (+33) 2 31 45 25 49

2 8