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

Templated Class as Polymorphic Function Parameter
by Joshua Perry 08 Jul '08

08 Jul '08

I apologize if this is a beginner question, but I can't find much on how something like this is supposed to work. I am using boost::iostreams to abstract away a couple of different methods of talking to our hardware devices. So I've created a device for each transport, each of which derive from device<bidirectional>; ip_device, serial_device, and usb_device. I then declare streams for each as stream<ip_device>, etc... Now that I have the streams, I have a class that communicates with the device and I would like to construct or initialize an object of that class with any one of the streams. I have yet to figure out how to form the constructor/function parameter to allow this. I've tried something like this, a stream of the base type of my devices: void init( stream< device<bidirectional> > str); I think something like this may work but I'm not sure if I want to template the function: template< typename T> void init(stream<T> str); A reference to any kind of discussion about using templates in such a way would help me in more than just this instance. Thanks for any input, Josh

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[gil] new opencv extension
by Christian Henning 08 Jul '08

08 Jul '08

Hi there, over the past few weeks I have rewritten the current opencv extension. Now there is a lot more functionality available as it was before. The following topics are covered: * converting colorspaces ( gray, rgb, rgba, xyz, hsv, hls, and lab ) * drawing primitives ( line, rectangles, circle, polyline, and text ) * edge detection ( sobel, laplace, canny, ... ) * resizing images( nearest neighbor, linear, area, and cubic ) * smoothing ( blur, gaussian, median, and bilateral ) As usual this extension is header only, but a user would need to make the opencv headers and libs available for compiling and linking. You can download the extension here using subversion: http://gil-contributions.googlecode.com/svn/trunk/gil_2 The folder structure is the same as with all boost libraries. There are some tests that can be used for testing and for learning the rather simple interface. Only the vc8 compiler has been used so far and though I would like ask for some assistance for making the extension compilable with gcc, for instance. Please give me some insight of what you think and about what functionality you might miss. I started to toy around with Tom Brinkman's idea of stacking up operations to batch process them which you can see in the drawing_test.cpp. Regards, Christian BTW: OpenCV is distributed with the BSD license and if I understand wikipedia correctly there isn't any objection using it in commercial applications. "The BSD License allows proprietary commercial use, and for the software released under the license to be incorporated into proprietary commercial products. Works based on the material may even be released under a proprietary license (but still must maintain the license requirements)."[wikipedia]

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Re: [Boost-users] Boost Graph Library and Graphviz
by Ronald Garcia 08 Jul '08

08 Jul '08

Hi Giuseppe, The BGL GraphViz reader does handle arbitrary graph, vertex, and edge properties. I am attaching an example program that demonstrates how to handle the example that you present below. Cheers, ron On Jul 8, 2008, at 9:57 AM, Doug Gregor wrote: > > On Jul 8, 2008, at 6:28 AM, Giuseppe Di Guglielmo wrote: > >> Dear all, >> I am using BGL and Graphviz dot-representation of graph. I'd like >> to add >> more properties to graph represented via dot-language. For example >> consider >> this simple graph >> >> digraph >> { >> graph [name="GRAPH"] >> >> a [label="NODE_A", root="1"] >> b [label="NODE_B", root="0" >> >> a -> b [label="EDGE_1"] >> b -> c [lable="EDGE_2"] >> } >> >> I read it with READ_GRAPHVIZ >> http://www.boost.org/doc/libs/1_35_0/libs/graph/doc/ >> read_graphviz.html >> >> If now I will add one more property to graph, for example >> >> digraph >> { >> graph [name="GRAPH", identifier="CX2A1Z"] >> ... >> } >> >> How can I retrieve the value for identifier property? >> >>

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Boost:Function bind to overloaded member
by James Sutherland 08 Jul '08

08 Jul '08

The following code does not compile: struct X { int foo(int i) { return ++i; } template<class T> void foo( T& t ); }; int main() { boost::function<int(int)> f; X x; f = boost::bind( &X::foo, &x ); std::cout << f(5) << std::endl; } I get the error message "no matching function for call to ‘bind(<unknown type>, X*)" If I remove the "template<class T> void foo" method then it compiles fine. Is there a way to tell boost::bind to choose the int foo(int i) method rather than the "template<class T> void foo" method? James

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[fusion] join result
by Istvan Buki 08 Jul '08

08 Jul '08

Dear boost experts, I have difficulties using the fusion join algorithm result. Here is a small sample demonstrating the problem. namespace fields { struct one ; struct two ; } typedef fusion::map < fusion::pair< fields::one, std::string >, fusion::pair< fields::two, std::string > > rec_t ; int main() { rec_t r1( std::string( "1" ), std::string( "2" ) ) ; rec_t r2( std::string( "10" ), std::string( "20" ) ) ; typedef fusion::result_of::join< const rec_t, const rec_t >::type res_type ; res_type res = fusion::join( r1, r2 ) ; // Compile error! fusion::at_key< fields::two >( res ) = std::string( "200" ) ; std::cout << res << std::endl ; } I can not modify the map fields because they are const. I tried changing the result type from typedef fusion::result_of::join< const rec_t, const rec_t >::type res_type ; to typedef fusion::result_of::join< rec_t, rec_t >::type res_type ; but that doesn't work neither. Can somebody explain how to assign the result of a join to a variable that I can modify later using functions like at_key, erase_key,... ? Thanks

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Retrieving parsed separators in boost::tokenizer
by Carlos Alvarez 08 Jul '08

08 Jul '08

Hi, When I use multiple separator to tokenize a string with boost::char_separator<char> sep( ".,:;" ) as example, i'd like to know if there could be some to iterate parsed separators, just like we can iterate parsed tokens. In my case, I need to know, with a defined separators list, which are the most used in a user defined text. Thnx Carlos Alvarez

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std::string <-> std::wstring conversion?
by Ákos Maróy 08 Jul '08

08 Jul '08

Hi, I saw a thread from 4 years ago on this topic here: http://lists.boost.org/Archives/boost/2004/12/77721.php is there any definitive way to go since then? Akos

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[boost-users][bind/lambda] how to
by Igor R 08 Jul '08

08 Jul '08

Hello, struct Inner { bool good() const; }; struct Outer { Inner inner_; const Inner &inner() const { return inner_; } }; std::vector<Outer> outers; I'd like to find Outer whose Inner is good(): std::find_if(outers.begin(), outers.end(), ?); How should I use boost::bind or boost::lambda to tell the stl algorithms to call Inner::good()? Thank you in advance!

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thread library name with mingw
by frederic.bron＠alcan.com 08 Jul '08

08 Jul '08

I am building boost from cygwin for win32 using gcc -mno-cygwin. As I use the flag --layout=system, why do I obtain the following name for the boost-thread library: libboost_thread_win32-mt.a. I would expect libboost_thread-mt.a only? Of course this is a consequence of flag threadapi=win32 but why does not layout=system override this file name? Here is my command line: $ bjam -d2 -j4 -sBZIP2_INCLUDE=/cygdrive/d/Softs/bzip2_msw/include -sBZIP2_LIBPATH=/cygdrive/d/Softs/bzip2_msw/lib -sNO_ZLIB=1 link=static threading=multi runtime-link=shared threadapi=win32 --layout=system --user-config=user-config.jam --without-python release install user-config.jam contains: using gcc : : : <cflags>-mno-cygwin <cflags>-DBOOST_WINDOWS_API <cxxflags>-mno-cygwin <cxxflags>-DBOOST_WINDOWS_API <compilerflags>-mno-cygwin <compilerflags>-DBOOST_WINDOWS_API <linkflags>-mno-cygwin ; F. Bron Avis : Ce message et toute pièce jointe sont la propriété d'Alcan et sont destinés seulement aux personnes ou à l'entité à qui le message est adressé. Si vous avez reçu ce message par erreur, veuillez le détruire et en aviser l'expéditeur par courriel. Si vous n'êtes pas le destinataire du message, vous n'êtes pas autorisé à utiliser, à copier ou à divulguer le contenu du message ou ses pièces jointes en tout ou en partie. Notice: This message and any attachments are the property of Alcan and are intended solely for the named recipients or entity to whom this message is addressed. If you have received this message in error please inform the sender via e-mail and destroy the message. If you are not the intended recipient you are not allowed to use, copy or disclose the contents or attachments in whole or in part.

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[boost-users][Multi-Index] crash in equal_range()
by Igor R 07 Jul '08

07 Jul '08

Hello, I've got a multi_index_container with few indices, as follows: struct Record { // some data }; typedef mi::multi_index_container< Record, mi::indexed_by< mi::ordered_non_unique<mi::tag<Record::stream>, mi::member<Record, int, &Record::streamID_> >, mi::ordered_non_unique<mi::tag<Record::setting>, mi::member<Record, int, &Record::settingID_> > > > Records; typedef Records::index<Record::stream>::type RecordsByStream; typedef Records::index<Record::setting>::type RecordsBySetting; Records records_; Then I insert 1 Record into records_. Later in the code I do the following lookup: RecordsBySetting bySetting = records_.get<Record::setting>(); std::pair<RecordsBySetting::iterator, RecordsBySetting::iterator> sameSetting = bySetting.equal_range(1); // record with setting id == 1 exists in the container! In the last line, in equal_range() I've got an exception (access violation). Am I doing something wrong? Any help would be greatly appreciated! Some tracing: The crash is in ordered_index::equal_range(const CompatibleKey& x) in its 1st line: std::pair<node_type*,node_type*> p= ordered_index_equal_range(root(),header(),key,x,comp); An attepmt to access the root() fails. Here is the call stack: SomeProg.exe!boost::multi_index::detail::ordered_index_node_compressed_base<std::allocator<void> >::parent_ref::operator boost::multi_index::detail::ordered_index_node_impl<std::allocator<void> > *() Line 161 + 0x5 bytes C++ SomeProg.exe!boost::multi_index::detail::ordered_index<boost::multi_index::member<Record,int,8>,std::less<int>,boost::multi_index::detail::nth_layer<2,Record,boost::multi_index::indexed_by<boost::multi_index::ordered_non_unique<boost::multi_index::tag<Record::streamable,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na>,boost::multi_index::member<Record,int,4>,boost::mpl::na>,boost::multi_index::ordered_non_unique<boost::multi_index::tag<Record::setting,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na>,boost::multi_index::member<Record,int,8>,boost::mpl::na>,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na>,std::allocator<Record> >,boost::mpl::vector1<Record::setting>,boost::multi_index::detail::ordered_non_unique_tag>::root() Line 879 + 0x40 bytes C++ SomeProg.exe!boost::multi_index::detail::ordered_index<boost::multi_index::member<Record,int,8>,std::less<int>,boost::multi_index::detail::nth_layer<2,Record,boost::multi_index::indexed_by<boost::multi_index::ordered_non_unique<boost::multi_index::tag<Record::streamable,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na>,boost::multi_index::member<Record,int,4>,boost::mpl::na>,boost::multi_index::ordered_non_unique<boost::multi_index::tag<Record::setting,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na>,boost::multi_index::member<Record,int,8>,boost::mpl::na>,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na,boost::mpl::na>,std::allocator<Record> >,boost::mpl::vector1<Record::setting>,boost::multi_index::detail::ordered_non_unique_tag>::equal_range<int>(const int & x=1) Line 493 + 0x20 bytes C++

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