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

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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