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

Extracting libraries from boost?
by Angel Tsankov 31 Oct '07

31 Oct '07

Can libraries in boost be used on their own, i.e. can I extract one of them and use it in a project? In particular, I only need the smart_ptr and ref libraries in one of my projects.

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Regex: Invalid preceding regular expression problem
by Brian Krahmer 31 Oct '07

31 Oct '07

Hello, I'm a new member to the mailing list. BTW, thanks to everyone who contributes to boost. It's a fantastic software. I am having a problem with building an expression object. The line in question reads 'boost::regex expression(pattern, options);', where I'm using the boost::regex::extended option, and the pattern looks like this: "^([0-7]\\..*|8\\.0(\\.[0-3](\\.[0-3])?)?)[^.0-9]*?$". I fired up a ruby interpreter, and it handled the regex fine (using "8.0.0.1 (en-US)" as a positive, and "9.0.0.1 (en-US)" as a negative). Can anybody tell me what is wrong with this regex, or confirm that there may be a bug in the library? thanks, brian

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[Regex] Why does this example code not compile?
by Mike Thornton 31 Oct '07

31 Oct '07

Using g++ on a GNU Ubuntu Linux 7.04 machine, I am unable to compile the boost example code (saved as test.cpp) at http://www.boost.org/libs/regex/example/snippets/partial_regex_match.cpp Although I can compile my own code which does not use boost, I get a lot of garbled output from the example code...part of which is listed below. Any ideas on what is wrong and how to fix it? test.cpp : (.text._ZN5boost9re_detail12perl_matcherIN9__gnu_cxx17__normal_iteratorIPKcSsEESaINS_9sub_matchIS6_EEENS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEEC1ES6_S6_RNS_13match_resultsIS6_S9_EERKNS_11basic_regexIcSD_EENS_15regex_constants12_match_flagsES6_[boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::perl_matcher(__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, __gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, boost::match_results<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > > >&, boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags, __gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >)]+0xea): undefined reference to `boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::construct_init(boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags)' Thanks. Mike

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Using date/time to format date strings
by Andrew 31 Oct '07

31 Oct '07

Hi all, I'm trying to use the date time library to to do some string formatting but I'm afraid there's something I'm missing. What I'd like to do is feed in a string "05/Aug/2007 11:30" and convert it to an ISO formatted string - could anyone point me in the right direction? I've examined both the documentation and the sample code in io_tutorial.cpp but I'm afraid it hasn't helped - the code below is as far as I've gotten and simply returns the input string unchanged. I'm using boost 1.34.1 with MSVC 2005. Thanks much, Andrew //Begin snippit string formatDate(string inpDate) { stringstream ss; local_date_time checkDate(not_a_date_time); local_time_input_facet* input_facet = new local_time_input_facet(); local_time_facet* output_facet = new local_time_facet(); ss.imbue(locale(locale::classic(), output_facet)); ss.imbue(locale(ss.getloc(), input_facet)); input_facet->format("%d/%b/%Y %H:%M"); output_facet->set_iso_format(); ss << inpDate; return ss.str(); }

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[statechart] direct manipulation of event queue?
by Chris Paulse 30 Oct '07

30 Oct '07

How easy would it be to directly remove specific types of events from a state machine's event queue?

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Beginner question about PocketPC 2003
by Dmytro Bogovych 30 Oct '07

30 Oct '07

Greetings. I downloaded 1.34.1 build from Boost Consulting. It comes with prebuilt libraries for VS 2005. I like it very much as I use Boost.Thread in my projects. But this package comes without prebuild libraries for PocketPC 2003 ARM target. How can I build them? I read about bjam but don't see what arguments I should set. This - bjam --v2 "-sTOOLS=msvc" "-sBUILD=release <windows>pocketpc2003 <charset>wide <architecture>arm4" install doesn't work. Sorry for stupid question.

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[multi-index] bug or not?
by Ovanes Markarian 30 Oct '07

30 Oct '07

Hello! I have a question regarding the multi-index behaviour, Let's say I have a multi-index container containing some hashed keys. What should happen with this container is empty and I retrieve an indexed by hash view into it? I have on Visual C++ 2005 an access violation, since I am trying to retrieve a view by it's hashed keys into the const container. Many thanks, Ovanes

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Errors in custom predicate support docu
by Jens Seidel 30 Oct '07

30 Oct '07

Hi, I tried a few times to report the following bug to trac but it was always rejected as spam!?? According to http://www.boost.org/libs/test/doc/components/test_tools/custom_predicate_s… there exists a class boost::test_tools::extended_predicate_value. (Or is it a user supplied class?) Nevertheless I didn't found such a class in Boost.test and even trunk contains only predicate_result which is different. This makes predicate support very hard to use for me. Please provide proper documentation for it! I hope this is the right way to run tests in a loop and to condense the output. Jens

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serialization: curious un-serializing issue RFI
by Hugh Hoover 30 Oct '07

30 Oct '07

I have a curious problem that's just sprung up, after changing from using plain-old-pointers to using boost::shared_ptrs internally in my data structures (stl hash_map and map) The problem is that while the XML archive works correctly, both text and binary fail (they all used to work). This is using gcc 4.0.1 on darwin and VC8 on windows, boost version is 1.34.1 The failure occurs while unserializing an archive, specifically when trying to read back a shared_ptr to an already unserialized object. In the archive, it shows the object (pointer) as an object_reference (the same reference id in XML and text). While the XML version reads the pointer back correctly, the text version fails and returns NULL. I have not determined the exact reason why the text version fails (it doesn't throw, just returns NULL). The serialization does not appear to have any problems. Since my actual code is reasonably complicated, and I haven't created a simplified version that demonstrates the problem, I'm not including code now - I'd just like to find out if this sounds familiar to anyone, that is, working under XML but failing under text and binary. It does appear to be shared_ptr specific, too, since everything was working before replacing naked pointers with shared_ptrs.

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Serialization and raw pointer arrays
by Eric 30 Oct '07

30 Oct '07

Hi, I've inherited some complex math code that makes large usage of Matrices based on raw pointer arrays. I need to serialize/deserialize these arrays as is and am looking to use boost::serialization package. My attempt at doing so results in the following errors (mostly about non integral array size). As I do not know the array size when it is created (and lots of code accesses the pointer directly as a chunk of memory that has been allocated, what are my options to get this to work? Errors: /usr/include/boost/archive/detail/oserializer.hpp: In function `void boost::archive::save(Archive&, T&) [with Archive = boost::archive::text_oarchive, T = Dummy]': /usr/include/boost/archive/basic_text_oarchive.hpp:78: instantiated from `void boost::archive::basic_text_oarchive<Archive>::save_override(T&, int) [with T = Dummy, Archive = boost::archive::text_oarchive]' /usr/include/boost/archive/detail/interface_oarchive.hpp:78: instantiated from `Archive& boost::archive::detail::interface_oarchive<Archive>::operator<<(T&) [with T = Dummy, Archive = boost::archive::text_oarchive]' serialize_array.cpp:56: instantiated from here /usr/include/boost/archive/detail/oserializer.hpp:567: error: incomplete type `boost::STATIC_ASSERTION_FAILURE< false>' used in nested name specifier /usr/include/boost/archive/detail/oserializer.hpp:567: error: size of array has non-integral type `<type error>' Code: #include <boost/serialization/split_member.hpp> #include <fstream> #include <iostream> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> using namespace std; class Dummy { public: friend class boost::serialization::access; Dummy() {pVal=NULL;size=0;} ~Dummy() {delete [] pVal;} template<class Archive> void save(Archive & ar, const unsigned int version) const { ar & size; for (int i=0; i<size; i++) { ar & pVal[i]; } } template<class Archive> void load(Archive & ar, const unsigned int version) { ar & size; pVal = new int[size]; for (int i=0; i<size; i++) { ar & pVal[i]; } } int* pVal; int size; }; BOOST_CLASS_VERSION(Dummy, 1) int main(int argc, char** argv) { Dummy d; d.size = 5; d.pVal = new int[d.size]; for (int i=0; i< d.size; i++) { d.pVal[i] = i+10; } ofstream ofOut("testSer.txt"); { boost::archive::text_oarchive oa(ofOut); oa << d; } Dummy load; { ifstream ifIn("testSer.txt"); boost::archive::text_iarchive ia(ifIn); ia >> load; } cout << "size="<<load.size<<endl; for (int i=0; i< load.size; i++) { cout << load.pVal[i] <<endl; } return -1; } Thanks, Eric

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boost.graph python bindings: read_graphml: No to_python (by-value) converter found for C++ type: struct boost::graph_exception
by John Reid 30 Oct '07

30 Oct '07

Hi, When I try to read a graphml file an exception is thrown but cannot be passed back to python through boost.python as no converter is registered. I'm using SVN version 338 from https://svn.osl.iu.edu/svn/projects_viz/bgl-python. The output is: c:\dev\python\boost\graph\__init__.py in read_graphml(filename) 624 """ 625 try: --> 626 graph = Digraph.read_graphml(filename) 627 except UndirectedGraphError: 628 graph = Graph.read_graphml(filename) <type 'exceptions.TypeError'>: No to_python (by-value) converter found for C++ type: struct boost::graph_exception If I just try the following: bgl.Graph.read_graphml(filename) I get something that might be a different symptom of the same problem: <type 'exceptions.SystemError'>: 'finally' pops bad exception The graphml file is: <?xml version="1.0" encoding="UTF-8"?>  <graphml xmlns="http://graphml.graphdrawing.org/xmlns/graphml" xmlns:y="http://www.yworks.com/xml/graphml" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://graphml.graphdrawing.org/xmlns/graphml http://www.yworks.com/xml/schema/graphml/1.0/ygraphml.xsd"> <key id="d0" for="node" yfiles.type="nodegraphics"/> <key id="d1" for="edge" yfiles.type="edgegraphics"/> <graph id="G" edgedefault="directed"> <node id="n0"> <data key="d0" > <y:ShapeNode > <y:Geometry x="0.0" y="0.0" width="30.0" height="30.0"/> <y:Fill color="#FFCC00" transparent="false"/> <y:BorderStyle type="line" width="1.0" color="#000000" /> <y:NodeLabel x="13.0" y="13.0" width="4.0" height="4.0" visible="true" alignment="center" fontFamily="Dialog" fontSize="13" fontStyle="plain" textColor="#000000" hasBackgroundColor="false" hasLineColor="false" modelName="internal" modelPosition="c" autoSizePolicy="content"></y:NodeLabel> <y:Shape type="ellipse"/> </y:ShapeNode> </data> </node> <node id="n1"> <data key="d0" > <y:ShapeNode > <y:Geometry x="18.0" y="68.0" width="30.0" height="30.0"/> <y:Fill color="#FFCC00" transparent="false"/> <y:BorderStyle type="line" width="1.0" color="#000000" /> <y:NodeLabel x="13.0" y="13.0" width="4.0" height="4.0" visible="true" alignment="center" fontFamily="Dialog" fontSize="13" fontStyle="plain" textColor="#000000" hasBackgroundColor="false" hasLineColor="false" modelName="internal" modelPosition="c" autoSizePolicy="content"></y:NodeLabel> <y:Shape type="rectangle"/> </y:ShapeNode> </data> </node> <edge id="e0" source="n0" target="n1"> <data key="d1" > <y:PolyLineEdge > <y:Path sx="0.0" sy="0.0" tx="0.0" ty="0.0"/> <y:LineStyle type="line" width="1.0" color="#000000" /> <y:Arrows source="none" target="standard"/> <y:BendStyle smoothed="false"/> </y:PolyLineEdge> </data> </edge> </graph> </graphml> Thanks for a great library, John.

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Re: [Boost-users] [reflection] Compilation errors
by Ovanes Markarian 30 Oct '07

30 Oct '07

Hi Christian, I assume you need to use either wchar_t or set in Visual C++ the charset not to multi-byte but not implemented. Otherwise you are trying to use pass single-byte strings as multi-byte string params. Best Regards, Ovanes On 10/29/07, Christian Henning <chhenning(a)gmail.com> wrote: > > Hi there, I just pulled the latest reflection code from the sandbox > and tried to compile the example. But unfortunately there are > compilation errors. > > For example: > > c:\boost-sandbox\boost\extension\impl\library_impl.hpp(37) : error > C2664: 'LoadLibraryW' : cannot convert parameter 1 from 'const char *' > to 'LPCWSTR' > > Is the relection lib in a usable stage? > > Thanks, > Christian > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users >

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using ref() with threads
by Andrey Tcherepanov 30 Oct '07

30 Oct '07

Hello folks, we recently got stuck with one minor inconvenience with boost thread (which we fixed), but somehow we cannot explain why it did not work. We are using 1.34.1 and VS 2005 SP1 the sample that did not work properly was aproximately like this (not compilable) class Super_Func { protected: bool * _die; SomeObscureIPWorksBasedDaemon _daemon; public: Super_Func(bool* t) : _die(t), _daemon("localhost", 12345) {} void operator()() { while (!*_die) { _daemon.do_background_stuff(); if (_daemon.has_data()) us_process_data(_daemon.get_data()); } } }; int main() { bool die = false; Super_Func sf(&die); boost::thread main_thread(boost::ref(sf)); main_thread.join(); return 0; } Everything compiled without hick-up, and even created the thread (well, at least debugger showed it, and stopped in while loop). But all the TCP/IP related stuff in thread did not work (was sort of stuck). Once we replaced above with void Super_Func(bool* die) { SomeObscureIPWorksBasedDaemon _daemon("localhost", 12345); while (!*_die) { _daemon.do_background_stuff(); if (_daemon.has_data()) us_process_data(_daemon.get_data()); } } int main() { bool die = false; boost::thread main_thread(boost::bind(Super_Func, &die)); main_thread.join(); return 0; } everything magically worked! Well, if I do not miss some obvious error somewhere in the first example (which I might)... then I do not know why it did not work. I was under impression that ref() is just a way to pass "reference" to the anything (including functional object), so it will create copy of ref, and not Super_Func class itself. Any insight is appreciated. Thank you very much, Andrey.

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Request to know about "dynamic expression evaluation"
by Borse, Ganesh 29 Oct '07

29 Oct '07

Hi, I would like to perform the dynamic expression evaluation in my c++ application. The dynamic expressions are like the SQL queries. Since the expressions could be nested & hence the parsing & evaluation of such expressions is reducing the performance of my application. May I please know, whether BOOST provides a support for such dynamic expression evaluation in C++? Please guide. Thanks in advance for the guidance. Regards, Ganesh ============================================================================== Please access the attached hyperlink for an important electronic communications disclaimer: http://www.credit-suisse.com/legal/en/disclaimer_email_ib.html ==============================================================================

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bis
by question boost 29 Oct '07

29 Oct '07

Hi, it seems the problem is at step 2. When I do: C:\Documents and Settings\src\boost\tools\build\v2> bjam --version I get the message: Mingwbing++ n'est pas reconnu en tant que command interne ou externe,un programme exécutable ou un fichier de commandes. Change the "\" by "/" is apparently not the solution. Thank you for your help. David _________________________________________________________________ Vous êtes plutôt Desperate ou LOST ? Personnalisez votre PC avec votre série TV préférée ! http://specials.divertissements.fr.msn.com/SeriesTV.aspx

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Newbie: Building Boost.Python Libs Nomenclature
by Shawn Cook 29 Oct '07

29 Oct '07

I just need a sanity check: I would like to embed a Python interpreter in my C++ application. I am following all the instructions as accurately as I can (http://www.boost.org/more/getting_started/windows.html) When I build the Python library binary (as mentioned in the Boost.Python installation instructions) I do not get any errors. If necessary I can respond with my Boost.Build output - but it's rather lengthy. Anyway, this paragraph in the Boost.Python Embedding tutorial says I'm looking for a library file named "boost_python_debug.lib" which does not exist. Here is the paragraph in question: ' Boost.Python's library comes in two variants. Both are located in Boost's /libs/python/build/bin-stage subdirectory. On Windows, the variants are called boost_python.lib (for release builds) and boost_python_debug.lib (for debugging). If you can't find the libraries, you probably haven't built Boost.Python yet. See Building and Testing on how to do this.' (from: http://www.boost.org/libs/python/doc/tutorial/doc/html/python/embedding.html) But I'm not getting any build errors, in fact I'm building all the different MSVC runtime variants (debug, release, static, dynamic, etc) and they all appear to be built - but they are named different than "boost_python.lib" and are not in the /libs/python/build/bin-stage directory. Is this paragraph just deprecated and needing some revisiting by the faithful Boost Technical Writers? Thanks, folks, -S. _________________________________________________________________ Peek-a-boo FREE Tricks & Treats for You! http://www.reallivemoms.com?ocid=TXT_TAGHM&loc=us

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START. Is anyone going to explain me the way to use BOOST in a C++ program?
by question boost 29 Oct '07

29 Oct '07

Hi, 1 My program under Code Blocks makes use of Boost. The arrangement of my files is the following: in the directory of the source files of my program there is the directory "boost" containing the following directories: "filesystem", "config", "iterator","range","detail", "mpl", "preprocessor", "tools" and the file boost-build.jam. 2 The file that makes use of boost in my project contains the following lines: #include <string> using namespace std; #include "boost\filesystem\path.hpp" #include "boost\filesystem\operations.hpp" using namespace boost::filesystem; 3 At build I get the message :"boost/preprocessor/config/config.hpp" no such file or directory and several other similar messages about other files of the same directory and about other files of the "mpl" directory. I've followed all the instructions here http://www.boost.org/doc/html/jam/building.html and here http://www.boost.org/doc/html/bbv2/installation.html At end of step 4 of http://www.boost.org/doc/html/bbv2/installation.html, the problem at build remains the same:I get the same message. Thank you for your help. David _________________________________________________________________ Découvrez le blog Messenger Le Meilleur du Web : toutes les vidéos qui buzzent le plus sur Internet ! http://meilleurduweb.spaces.live.com/

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shared_ptr memory leak in VC2005?
by zzp good 29 Oct '07

29 Oct '07

hi, guys, I found memory leak using the following code: #include <boost\array.hpp> #include <boost\shared_ptr.hpp> using namespace boost; class C { public: shared_ptr<C> pNext; }; void test() { shared_ptr<C> c0(new C()); shared_ptr<C> c1(new C()); c0 -> pNext = c1; c1 -> pNext = c0; } void main() { test(); _CrtDumpMemoryLeaks(); } when running with F5, it said: Detected memory leaks! Dumping objects -> d:\program files\microsoft visual studio 8\vc\include\crtdbg.h(1147) : {126} normal block at 0x003A64B0, 16 bytes long. Data: < E hd: > C4 17 45 00 01 00 00 00 01 00 00 00 68 64 3A 00 d:\program files\microsoft visual studio 8\vc\include\crtdbg.h(1147) : {125} normal block at 0x003A6468, 8 bytes long. Data: < c: d: > D0 63 3A 00 18 64 3A 00 d:\program files\microsoft visual studio 8\vc\include\crtdbg.h(1147) : {124} normal block at 0x003A6418, 16 bytes long. Data: < E c: > C4 17 45 00 01 00 00 00 01 00 00 00 D0 63 3A 00 d:\program files\microsoft visual studio 8\vc\include\crtdbg.h(1147) : {123} normal block at 0x003A63D0, 8 bytes long. Data: <hd: d: > 68 64 3A 00 B0 64 3A 00 Object dump complete. Any body have an idea about this? Thanks very much.

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[signal,bind] upgrade problem from 1.33 to 1.34
by David Angelo 29 Oct '07

29 Oct '07

Hi folks, I have a problem with upgrading from boost version 1.33 to 1.34. My code runs fine with 1.33, but when compiling and linking againt 1.34 I get the following runtime error (backtrace): <backtrace> #0 0x81d4c9b2 in void boost::function1<void, float, std::allocator<void> >::ass ign_to<boost::_bi::bind_t<void, boost::_mfi::mf1<void, fpCTPart, float>, boost:: _bi::list2<boost::_bi::value <fpCTPart*>, boost::arg<1> (*)()> > >(boost::_bi::bi nd_t<void, boost::_mfi::mf1<void, fpCTPart, float>, boost::_bi::list2<boost::_bi ::value<fpCTPart*>, boost::arg<1> (*)()> >)::stored_vtable () from /home/david/eclipseM6/toolManagement/lib/libfpCTToolPack.so #1 0xb4438841 in boost::function0<void, std::allocator<void> >::clear ( this=0xa1a03fc) at /usr/include/boost/function/function_template.hpp:388 #2 0xb4438879 in ~function0 (this=0xa1a03fc) at /usr/include/boost/function/function_template.hpp:313 #3 0xb443889d in ~function (this=0xa1a03fc) at /usr/include/boost/function/function_base.hpp:92 #4 0x81a34c39 in ~holder (this=0xa1a03f8) at /home/david/apps/boost_1_34_1/include/boost-1_34_1/boost/any.hpp:106 #5 0x81137b41 in boost::signals::detail::named_slot_map::insert () from /home/david/apps/boost_1_34_1/lib/libboost_signals-gcc41-1_34_1.so.1.34. 1 #6 0x8113b562 in boost::signals::detail::signal_base_impl::connect_slot () from /home/david/apps/boost_1_34_1/lib/libboost_signals-gcc41-1_34_1.so.1.34. 1 #7 0x81a36e58 in boost::signal0<void, boost::last_value<void>, int, std::less<i nt>, boost::function<void ()(), std::allocator<void> > >::connect ( this=0x82eac060, in_slot=@0xbfe145f0, at=boost::signals::at_back) ---Type <return> to continue, or q <return> to quit---bt at /home/david/apps/boost_1_34_1/include/boost-1_34_1/boost/signals/signal_template.hpp:286 #8 0x81b359f6 in fpCTPart::initPart (this=0x82eaa7f0) at /home/david/eclipseM6/toolManagement/extensions/fpCTToolPack/parts/src/fpCTPart.cpp:173 </backtrace> Line 173 in fpCTPart.cpp is: geomNode->sigPreLoad.connect(boost::bind(&fpCTPart::slotFilePreLoaded, this)); Are there any changes between these to versions in the bind/signal library? (Are they not backward compatible?) Thanks in advance. Regards, David

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[signals] How not to ignore 'trackable'?
by Nat Goodspeed 27 Oct '07

27 Oct '07

I have a callback design based around Boost.Signals. The documentation says: http://boost.org/doc/html/signals/tutorial.html#id1627926 "Warning: User-defined function objects and function objects from other libraries (e.g., Boost.Function or Boost.Lambda) do not implement the required interfaces for trackable object detection, and will silently ignore any bound trackable objects. Future versions of the Boost libraries will address this limitation." I would like to define a filter function object to be used something like this: // define signal_t, handler_t typedef boost::signal<void()> signal_t; typedef signal_t::slot_type handler_t; signal_t mySignal; // straightforward use case struct Listener: public boost::signals::trackable { void someMethod() {} }; Listener* myListener = new Listener(); mySignal.connect(boost::bind(&Listener::someMethod, myListener)); // the following should disconnect delete myListener; mySignal(); // should do nothing // define filter function object struct Filter { Filter(const handler_t& handler, somedata_t somedata): mHandler(handler), mSomeData(somedata) {} void operator()() { if (mSomeData) { mHandler(); } } handler_t mHandler; somedata_t mSomeData; }; // use filter function object myListener = new Listener(); mySignal.connect(Filter(boost::bind(&Listener::someMethod, myListener), somedata)); // doc promises the following will NOT disconnect delete myListener; mySignal(); // the dreaded undefined behavior Unfortunately there are two hurdles to getting there. 1. How could I code Filter to honor the 'trackability' of the passed-in handler? 2. slot_type is not itself callable: mHandler() doesn't work. 2a. I could use boost::function for handler_t instead: typedef boost::function<void()> handler_t; but the documentation promises that this, too, will ignore Filter's trackable base class. 2b. I could make Filter store a signal_t instead of a handler_t. Filter's constructor could call mHandler.connect(handler) instead of initializing mHandler from handler. But that doesn't work because signal_t is noncopyable, and passing a Filter instance to connect() copies it. I'd be willing to make Filter trackable, stipulating that Filter instances must live on the heap: mySignal.connect(new Filter(etc.)); // or boost::bind() of same Then Filter could store signal_t because the Filter object wouldn't be copied. When the Listener object is destroyed, it would automatically disconnect from the Filter's signal_t. But that would leave me with an orphan Filter object with an empty signal_t permanently connected to mySignal. Could Filter be informed when slots are disconnected from its contained signal_t? When the last slot is disconnected, it could 'delete this'. With Filter trackable, that would disconnect it from mySignal, and everyone would be happy. (There's the performance cost of introducing another signal object through which the call must be forwarded, but I hope that will be negligible.) So: is there any way for Filter to intercept control when the last (only) slot disconnects from Filter::mHandler? (Filter stores a subclass of signal_t?) Is there any other way to accomplish what I'm trying to do here? Thanks.

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RegExp - Callback function
by Golan Trevize 27 Oct '07

27 Oct '07

Hello. First... I'm sorry for my english. And second - I've got small problem. I need use regexp. The idea is that I use 'replace', it find some text like in expression and this will be an input for function... then in function something happen and output of the function replace in text the input of the function... For example I've got text "Solution: 5 and 4". Regular expression is "[0-9]" And the function is "add5" int add5(int input){return input+5} And the output of this function replace the number with number+5... And in the end text will be: "Solution: 10 and 9" In C++ with Boost? I don't know how can I do it... something like this.... #include <cstdlib> #include <iostream> #include <boost/regex.hpp> using namespace std; using namespace boost; // the callback function string add5(string x) { int v; v =atoi(x.c_str()) + 5; string vystup = (char *)v; return vystup; } int main(int argc, char *argv[]) { string t; string k; t = "Solution: 4"; regex expression("[0-9]"); k=regex_replace(t, expression,add5, boost::match_default|boost::format_all); cout << k << endl; system("PAUSE"); return EXIT_SUCCESS; } How can I rewrite this line: k=regex_replace(t, expression,add5, boost::match_default|boost::format_all); And how I change the callback function add5... If someone know, thank you for answers and advices.

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[typeof] Duplicate definition of boost::type_of::push_back
by Dave Jenkins 27 Oct '07

27 Oct '07

Hi, I'm testing with BOOST_TYPEOF_LIMIT_SIZE greater than 50 and native typeof disabled. I get a "class template has already been defined" error on "template<class V, class T> struct push_back" whenever BOOST_TYPEOF_LIMIT_SIZE is *not* a multiple of 50. This is because push_back is defined in both "typeof/vector.hpp" and, for example, "typeof/vector50.hpp". My fix is to change the push_back definition in "typeof/vector.hpp" to: # if BOOST_TYPEOF_LIMIT_SIZE < 50 template<class V, class T> struct push_back { typedef V type; }; # endif Can someone please confirm that this is the correct fix? A tiny program demonstrating the problem is listed below. Thanks, Dave Jenkins #define BOOST_TYPEOF_COMPLIANT #define BOOST_TYPEOF_LIMIT_SIZE 51 #include <boost/typeof/typeof.hpp> int main(){ return 0; }

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[type_traits] upcoming standard question...
by Ovanes Markarian 26 Oct '07

26 Oct '07

Hello! I am just wondering, that the upcoming standard does not provide the is_rvalue type_trait. At least I did not find it in the mailings. Since there is an is_reference trait and rvalues are going to be added to the standard, don't you think the is_rvalue should be a part of upcoming standard type_traits? Many Thanks, Ovanes

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boost::serialization Qestion about versioning.
by Oleg Udovenko 26 Oct '07

26 Oct '07

Hi, As I can see from the documentation the library has only a forward compatibility. 3. Independent versioning for each class definition. That is, when a class definition changed, older files can still be imported to the new version of the class. Is there any way to achieve a backward compatibility? Thanks, Oleg.

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Boost.Test: problem with BOOST_CHECK_EQUAL for negative chars
by Mignon Belongie 26 Oct '07

26 Oct '07

The following causes a fatal error (at least for me): char c1 = -2; char c2 = -2; BOOST_CHECK_EQUAL(c1, c2); The message is: Assertion failed: (unsigned)(c + 1) <= 256 Thanks, Mignon

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