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

[Regex] Case insensitive pb
by f_mayot 07 Nov '02

07 Nov '02

Hi, Maybe a stupid question but I didn't manage to make my regular expression objects case insensitive. What should I do insted of this : boost::regex* pRegExp = new boost::wregex(sRegExp); ? Thanks. Fred

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Can't use adjacency_list AND adjacency_matrix in same program
by loopylozzysdad 06 Nov '02

06 Nov '02

Hi, It seems to me that you can't use adjacency_list AND adjacency_matrix in the same program. When I had both the relevant inludes in the program I got duplicate definition errors from the linker. Is this by design, or a bug? Cheers - Richard Howells (loopylozzydad at yahoo dot com)

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RE: [Boost-Users] shared_ptr capabilities
by Mark Storer 06 Nov '02

06 Nov '02

>I don't believe the above statement will affect me, >but I just want to be sure Correct. A language-level array is not an STL container. There IS a shared_ptr-like template called shared_array that calls "delete []" instead of "delete". Had to look that one up. It doesn't get used much. std::vector is a superior choice (in every situation I can think of). An STL container of shared_ptr's is just fine. Just don't create a circular reference. --Mark Storer Software Engineer Cardiff Software #include <disclaimer> typedef std::disclaimer<Cardiff> Discard; -----Original Message----- From: Collin Peters [mailto:yg-boost-users@m.gmane.org] Sent: Wednesday, November 06, 2002 1:04 PM To: boost-users(a)yahoogroups.com Subject: [Boost-Users] shared_ptr capabilities http://www.boost.org/libs/smart_ptr/shared_ptr.htm states that: "Normally, a shared_ptr cannot correctly hold a pointer to a dynamically allocated array. See shared_array for that usage." What I hope to use shared_ptr for, is to store pointers to a class in a vector, and that class will also have a vector that stores pointers via shared_ptr. example: class Foo { int a; } class one { int var1; int var2; std::vector<Foo> foo_vector; } class two { std::vector<one> one_vector; } I don't believe the above statement will affect me, but I just want to be sure Collin Peters Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

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shared_ptr capabilities
by Collin Peters 06 Nov '02

06 Nov '02

http://www.boost.org/libs/smart_ptr/shared_ptr.htm states that: "Normally, a shared_ptr cannot correctly hold a pointer to a dynamically allocated array. See shared_array for that usage." What I hope to use shared_ptr for, is to store pointers to a class in a vector, and that class will also have a vector that stores pointers via shared_ptr. example: class Foo { int a; } class one { int var1; int var2; std::vector<Foo> foo_vector; } class two { std::vector<one> one_vector; } I don't believe the above statement will affect me, but I just want to be sure Collin Peters

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Q: Problems building boost.python under cygwin
by "Schnörr, Claudius Dr." 06 Nov '02

06 Nov '02

Hello, I run into problems building boost under cygwin. It seems to be merely a matter of a wrong configuration or wrong scripts. After running 'bjam -sTOOLS=gcc -n > build.com' in boost/libs/python/build in order to get hands on the statements being executed by bjam, there had to be made a lot of textual replacements to get the statements in build.com run: Just to mention some: - replace '-isystem ' by '-I' - remove '-I""' - change shared library-names from *.so to *.dll - insert '-L <path_to_libpython2.2.dll> -lpython2.2' where shared libs are created In boost/libs/python/test, going the same way, there have in addition this changes to be made: - LD_LIBRARY_PATH=... --> PATH=$PATH:..., because cygwin uses PATH to look for .dlls My question: I think there have to be made more configurations than I did to create the boost.python-stuff under cygwin. Where have they to be done, and what? (I already configured environment variables like GCC_ROOT_DIRECTORY, GXX, PYTHON_ROOT, ...etc...) Any suggestions are welcome! Please send a copy of your answer to schnoerr(a)mailzone.com Thank you in advance, Claudius --------------------------------------------------------- This Mail has been checked for Viruses Attention: Encrypted mails can NOT be checked! ** Diese Mail wurde auf Viren geprueft Hinweis: Verschluesselte mails koennen NICHT auf Viren geprueft werden! ---------------------------------------------------------

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RE: [Boost-Users] set thread priority
by Mark Storer 05 Nov '02

05 Nov '02

I'd think you could get away with something like a set range, like 0 to 1000, and then map those values into whatever system is present. You could even use floating point values, 0.0 to 1.0, though people might look at you cross-eyed, at least until they got used to the idea. Then it's just a matter of mapping those ranges to whatever OS settings are present. You just state up front a couple caveats: Given two threads, A (higher priority) and B (lower priority), you only guarentee that A won't be given a lower underlying system priority than B. This would save you quite a bit of grief... particularly when someone wants threads with priority 1.0, 0.99 and 0.98. The thread with 0.98 might not run slower than the one with a 1.0 priority, but it certainly won't be faster. SOUNDS simple enough. At least to someone whose sum total multi-threading experience is a toy java applet and a dozen lines of boost::thread code. ;) --Mark Storer Software Engineer Cardiff Software #include <disclaimer> typedef std::disclaimer<Cardiff> Discard;

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set thread priority
by boxerab 05 Nov '02

05 Nov '02

Dear Boost Users, I am considering using the boost thread library; currently I use the Win32 API for threading on Windows. Is it possible to set the thread priority of a boost thread? Thanks! Aaron Boxer boxerab(a)NOSPAMyahoo.com

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can't compile johnson-eg.cpp with VC6
by chul_de_condares 05 Nov '02

05 Nov '02

I get the following errors when trying to compile the example code for johnson_all_pairs_shortest_paths. Has anyone ever seen this before? Thanks in advance. d:\swapps\source\axrt\c\boost\boost_1_29_0 \boost\graph\johnson_all_pairs_shortest.hpp(61) : error C2899: typename cannot be used outside a template declaration d:\swapps\source\axrt\c\boost\boost_1_29_0 \boost\graph\johnson_all_pairs_shortest.hpp(166) : see reference to function template instantiation 'bool __cdecl boost::johnson_all_pairs_shortest_paths(class boost::adjacency_list<struct boost::vec S,struct boost::vecS,struct boost::directedS,struct boost::no_property,struct boost::property<enum boost::edge_weight_t,int,struct boost::property<enum boost::edge_weight2_t,int,struct boost::no_property> >,struct boost::no_property,struct boost::li stS> &,int (&)[5][5],struct boost::vec_adj_list_vertex_id_map<struct boost::no_property,unsigned int>,struct boost::adj_list_edge_property_map<struct boost::directed_tag,int,int const &,unsigned int,struct boost::property<enum boost::edge_weight_t,i nt,struct boost::property<enum boost::edge_weight2_t,int,struct boost::no_property> > const ,enum boost::edge_weight_t>,int)' being compiled d:\swapps\source\axrt\c\boost\boost_1_29_0 \boost\graph\johnson_all_pairs_shortest.hpp(84) : error C2899: typename cannot be used outside a template declaration d:\swapps\source\axrt\c\boost\boost_1_29_0 \boost\graph\johnson_all_pairs_shortest.hpp(166) : see reference to function template instantiation 'bool __cdecl boost::johnson_all_pairs_shortest_paths(class boost::adjacency_list<struct boost::vec S,struct boost::vecS,struct boost::directedS,struct boost::no_property,struct boost::property<enum boost::edge_weight_t,int,struct boost::property<enum boost::edge_weight2_t,int,struct boost::no_property> >,struct boost::no_property,struct boost::li stS> &,int (&)[5][5],struct boost::vec_adj_list_vertex_id_map<struct boost::no_property,unsigned int>,struct boost::adj_list_edge_property_map<struct boost::directed_tag,int,int const &,unsigned int,struct boost::property<enum boost::edge_weight_t,i nt,struct boost::property<enum boost::edge_weight2_t,int,struct boost::no_property> > const ,enum boost::edge_weight_t>,int)' being compiled Error executing cl.exe. test.obj - 2 error(s), 0 warning(s)

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Boost Python v2 - extending and embedding - memory leaks, compiler warnings
by texrmex 04 Nov '02

04 Nov '02

First, I'm excited about the new work that's been done with Boost Python v2. I can't wait to see if it's enough to overcome the pitfalls that prevented me from getting past the evaluation stage with v1. I'm using VC7 IDE to build my project and link to python22.lib and boost_python.lib (built with VC7 command line tools using bjam). I'm attempting to extend and embed in my existing project, so I'm not building a dll, but and exe. First of all, can I do this? When it links it says "Creating library ....lib and object ....exp", and still creates an exe. If I don't include my test module (and thus boost/python.hpp) I don't get this message. I'm assuming that by defining a module, boost defines exports and the linker then creates the lib and exp, since there were exports? Although I've built dlls before, I really don't know the inner workings of the process. The following is a brief example of my module. At the bottom is a simple test function that I'm calling just to test importing of the module. When I call TestModule(), I get 2 memory leaks from the module definition section, one from the class definition, and the other from the method definition. If I remove these, I get no memory leaks, and if I add more classes and methods, I get one 12 byte leak per class and one 12 byte leak per method I add. I do not get a leak from defining the top level function "greet". /////////////////////////////////////////////////// #include <boost\python.hpp> using namespace boost::python; namespace { const char * greet() { return "Hello World"; } class CSimple { public: bool Test() { return true; } }; }; BOOST_PYTHON_MODULE(Test) { def("greet", greet); class_<CSimple>("Simple") .def("Test", &CSimple::Test) ; } void TestModule() { Py_Initialize(); initTest(); Py_Finalize(); } /////////////////////////////////////////////////// In addition to the memory leaks, I get a number of compiler warnings, similar to the following: d:\Boost\boost\python\instance_holder.hpp(18) : warning C4275: non dll-interface class 'boost::noncopyable' used as base for dll- interface struct 'boost::python::instance_holder' d:\Boost\boost\utility.hpp(50) : see declaration of 'boost::noncopyable' d:\Boost\boost\python\instance_holder.hpp(17) : see declaration of 'boost::python::instance_holder' *and* d:\Boost\boost\python\detail\exception_handler.hpp(34) : warning C4251: 'boost::python::detail::exception_handler::m_impl' : class 'boost::function2<R,T0,T1,Policy,Mixin,Allocator>' needs to have dll-interface to be used by clients of struct 'boost::python::detail::exception_handler' with [ R=bool, T0=const boost::python::detail::exception_handler &, T1=const boost::function0<void,boost::empty_function_policy,boost::empty_functi on_mixin,int> &, Policy=boost::empty_function_policy, Mixin=boost::empty_function_mixin, Allocator=int ] I was wondering if my project is not set up properly, and if these warnings might have something to do with the memory leaks. In v1 there was a vc project you could use for building boost python. This works well if you are planning on linking to a vc built project, since you can make sure your settings, paths and libs are consistent between the boost python lib and your project. I currently have 3 different sets of build tools (yes, 3 compilers) on this box, with several different versions of standard and other libraries, so making sure I have control of the paths and settings used is very important. This is one reason I'm weary of the jam environment. It's yet another build environment, one that I'm not familiar with, and one that I'm not going to be using with any other projects except to build boost python. So a question would be: how easy would it be for me to set up a VC project for building boost python? Has this already been done? Or am I barking up the wrong tree? Thanks in advance, -Tex

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RE: [Boost-Users] Iterator Adaptor Question
by Hickman, Greg 04 Nov '02

04 Nov '02

> -----Original Message----- > From: Mark Storer [mailto:mstorer@cardiff.com] > > You wrote up your sample so anyone could easily compile it... Thanks for noticing. :) > On > VC++ v6, I got two compiler errors: > > samplecode.cpp(58) : error C2663: 'reset' : 2 overloads have > no legal conversion for 'this' pointer > samplecode.cpp(59) : error C2678: binary '=' : no operator > defined which takes a left-hand operand of type 'const class > boost::shared_ptr<struct Shape const >' (or there is no > acceptable conversion) > > These errors are on the two lines you want to prevent. > > My first impression of the code was that it was already > illegal to perform those two actions. You shouldn't be able > to call non-const functions through a const_iterator, and > since neither reset() nor operator=() are const, no problem. > Right? I wasn't expecting the first error message, but the > second is in line with my expectations. > > I take it this code compiles for you? What tools/OS/etc are > you using? Unfortunately it does. I'm using Borland C++ Builder 5, for which I believe I have all of the available patches installed. (I'm using the IDE, but my command-line tells me I'm using Borland C++ 5.5.1. Borland gives away a set of free command-line tools that are distinct from the Builder IDE, and it may be that the compiler they give away is now more compliant than the one included in C++ Builder 5. If there is a way to point my IDE at the latest version of the free compiler, I don't know how to do it. I need to get gcc set up on my machine as a sanity check.) My first thought was that iterator_adaptor might be stripping away the const-ness from reference_type<const Const_shape_ptr>, and that the pointer type being generated was somehow pointing to a non-const Const_shape_ptr, thus allowing the indicated lines to compile. However, since you seem to get the desired results, perhaps the problem is with my compiler (or with Boost's support of it). Thanks very much for taking the time to respond. -Greg Hickman

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Property maps
by Edward Diener 04 Nov '02

04 Nov '02

The documentation for boost::property_map is awful, so would someone please explain to me what this implementation does and how it differs from std::map<> and std::multi_map<> ? I know this post sounds irascible and I am not trying to dump on Mr. Siek but really I do not understand what this idea is or why one should use it over and above what already exists in the C++ standard library. I only wish that Boost implementors would stop explaining their ideas through examples and start explaining them in logical ways in which a knowledge of the English language would suffice.

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RE: [Boost-Users] Iterator Adaptor Question
by Mark Storer 04 Nov '02

04 Nov '02

>Specifically, I'd like to prevent clients from writing the two lines >preceeding the return from main below. Can anyone help? Eh? You wrote up your sample so anyone could easily compile it... and I did. On VC++ v6, I got two compiler errors: samplecode.cpp(58) : error C2663: 'reset' : 2 overloads have no legal conversion for 'this' pointer samplecode.cpp(59) : error C2678: binary '=' : no operator defined which takes a left-hand operand of type 'const class boost::shared_ptr<struct Shape const >' (or there is no acceptable conversion) These errors are on the two lines you want to prevent. My first impression of the code was that it was already illegal to perform those two actions. You shouldn't be able to call non-const functions through a const_iterator, and since neither reset() nor operator=() are const, no problem. Right? I wasn't expecting the first error message, but the second is in line with my expectations. I take it this code compiles for you? What tools/OS/etc are you using? --Mark Storer Software Engineer Cardiff Software #include <disclaimer> typedef std::disclaimer<Cardiff> Discard; -----Original Message----- From: Hickman, Greg [mailto:greg.hickman@lmco.com] Sent: Friday, November 01, 2002 2:22 PM To: Boost-Users (Boost-Users(a)yahoogroups.com) Subject: [Boost-Users] Iterator Adaptor Question The following code illustrates a problem I'm having trying to use iterator_adaptor. Basically, I have a container of shared pointers to mutable, and I'd like to provide a const_iterator to clients that disallows modification of both the shared pointer as well as the pointee. Specifically, I'd like to prevent clients from writing the two lines preceeding the return from main below. Can anyone help? Thanks, Greg #include <boost/iterator_adaptors.hpp> #include <boost/shared_ptr.hpp> #include <vector> using namespace boost; using namespace std; struct Shape { virtual ~Shape() {} virtual void draw() const = 0; virtual void update() = 0; }; struct Concrete_shape : Shape { void draw() const {} void update() {} }; typedef shared_ptr<Shape> Shape_ptr; typedef shared_ptr<const Shape> Const_shape_ptr; struct Picture { typedef vector<Shape_ptr> Shapes; // Declare a const_iterator that converts // to the underlying Shape_ptr to a // Const_shape_ptr. Since the returned // Const_shape_ptr is a temporary, clients // shouldn't be allowed to modify it. typedef iterator_adaptor< Shapes::const_iterator, default_iterator_policies, value_type_is<Const_shape_ptr>, reference_is<const Const_shape_ptr>, iterator_category_is<input_iterator_tag> > const_iterator; const_iterator begin() const { return const_iterator(shapes_.begin()); } Shapes shapes_; }; int main(int argc, char* argv[]) { Picture pic; const Picture& cpic = pic; pic.shapes_.push_back(Shape_ptr(new Concrete_shape)); Picture::const_iterator i = cpic.begin(); // I'd like to prevent clients from writing... i->reset(new Concrete_shape); *i = Const_shape_ptr(new Concrete_shape); return 0; } Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

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Bug fix for format library
by Fred Jackson 04 Nov '02

04 Nov '02

I found a bug in the format library and fixed it. strm << boost::format("%64.64s") % "hello"; gave an access violation. It was caused by passing an argument greater than the string length to std::string::erase. I added a check so as not to try to erase text that is not there. Here is a diff of my small fix. < is feed_args.hpp from the boost_1_29_0 distribution. > is my fixed file. 158c158,162 < if (specs.truncate_ >= 0) --- > // @@@@@ fjackson 20021022 Added test to make sure we don't call > // std::string::erase with an arg greater than the length - this > // caused an access violation, noted on outputting a short string > // with a %64.64 format specifier. > if (specs.truncate_ >= 0 && specs.truncate_ < res.length())

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Wrapping a std::list with boost.python
by jefflholle 03 Nov '02

03 Nov '02

I've just started experimenting with version 2 of boost.python. In iterator.cpp, a std::list is wrapped using following code: typedef std::list<int> list_int; void push_back(list_int& x, int y) { x.push_back(y); } int back(list_int& x) { return x.back(); } . . . class_<list_int>("list_int") .def("push_back", push_back) .def("back", back) .def("__iter__", iterator<list_int>()) ; Is it possible to use the container methods instead of user defined functions? I've tried the code: class_<list_int>("list_int") .def("push_back", &list_int::push_back) .def("back", &list_int::back) .def("__iter__", iterator<list_int>()) ; This doesn't work. Am what I'm tried to do possible? If so, how?

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Re: linker problem with boost::thread
by Eske Christiansen 03 Nov '02

03 Nov '02

sorry, have fixed the problem. the correct way of linking with boost::thread is: g++ foo.cpp -lboost_thread -lpthread yours eske

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Making boost/test pause so the console can be read when running the tester from an IDE.
by Sean Shubin 03 Nov '02

03 Nov '02

My version of C++ builder does not pause to let me see console output. This makes it difficult to use boost/test while I am running the program from the IDE. The solution I found most useful, is to make the last test wait for the user to press enter. If anyone has solved this a different way, I would like to hear about it. #include <boost/test/unit_test.hpp> using boost::unit_test_framework::test_suite; using std::cout; using std::cin; using std::endl; void waitForUserToPressEnter() { cout << "Press <ENTER> to continue..." << endl; cin.get(); } test_suite* init_unit_test_suite(int argc, char* argv[]) { test_suite* test = BOOST_TEST_SUITE("Master test suite"); //add other tests here test->add(BOOST_TEST_CASE(&waitForUserToPressEnter)); return test; }

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linker problem with boost::thread
by Eske Christiansen 02 Nov '02

02 Nov '02

Hi all I'm new to this list and I have a question. I want to use the thread lib in g++ 2.96.110 under redhat 7.3 I have the test e.x. #include <boost/thread/thread.hpp> #include <iostream> void hello() { std::cout << "Hello world, I'm a thread!" << std::endl; } int main(int argc, char* argv[]) { boost::thread thrd(&hello); thrd.join(); return 0; } (from cuj.com) I try to compile with g++ -lboost_thread foo.cpp I get the the error(s): /tmp/ccdoKT37.o: In function `main': /tmp/ccdoKT37.o(.text+0x53): undefined reference to `boost::thread::thread(boost::function0<void, boost::empty_function_policy, boost::empty_function_mixin, allocator<boost::function_base> > const &)' /tmp/ccdoKT37.o(.text+0x75): undefined reference to `boost::thread::join(void)' /tmp/ccdoKT37.o(.text+0x86): undefined reference to `boost::thread::~thread(void)' /tmp/ccdoKT37.o(.text+0xbe): undefined reference to `boost::thread::~thread(void)' collect2: ld returned 1 exit status What do I do wrong. I don't want to use jam og bjam files because all my works i build by using automake. yours eske

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Basic Overviews Needed
by Sam Gentile 02 Nov '02

02 Nov '02

Hi Folks, I am new to Boost. I have looked at the Boost Documentation on the web (http://www.boost.org/libs/libraries.htm) and although it does a very excellent job of listing all the libraries, it doesn't really have any overview documents or tutorials as such. What I would like is some documents that tell me the power of Boost, what its useful for, etc. Any help would be greatly appreciated. Sam Gentile .NET Consultant ManagedCode(a)attbi.com http://www.samgentile.com http://radio.weblogs.com/0105852/ [Non-text portions of this message have been removed]

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compiler warning
by Matthew Galati 01 Nov '02

01 Nov '02

hi, using gcc version 2.96 20000731 (Red Hat Linux 7.3 2.96-110) does anyone know the pragma for turning this compiler warning off? or is this warning telling me something - do i need to configure my compiler differently? /home/mgalati/source/boost_1_29_0/boost/integer_traits.hpp:186: warning: ISO C++ does not support `long long' thanks, matt

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RE: [Boost-Users] Making boost/test pause so the console can be read when running the tester from an IDE.
by Sean Shubin 01 Nov '02

01 Nov '02

Tried it. The "return test" line completes the creation of the tests, but not their execution. When that breakpoint is reached, the tests have not been run, so there is not output. -----Original Message----- From: Jeff Garland [mailto:jeff@crystalclearsoftware.com] Sent: Friday, November 01, 2002 2:37 PM To: Boost-Users(a)yahoogroups.com Subject: RE: [Boost-Users] Making boost/test pause so the console can be read when running the tester from an IDE. > My version of C++ builder does not pause to let me see console output. This makes it > difficult to use boost/test while I am running the program from the IDE. The solution > I found most useful, is to make the last test wait for the user to press enter. If > anyone has solved this a different way, I would like to hear about it. Set a breakpoint on return test... HTH, Jeff

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Iterator Adaptor Question
by Hickman, Greg 01 Nov '02

01 Nov '02

The following code illustrates a problem I'm having trying to use iterator_adaptor. Basically, I have a container of shared pointers to mutable, and I'd like to provide a const_iterator to clients that disallows modification of both the shared pointer as well as the pointee. Specifically, I'd like to prevent clients from writing the two lines preceeding the return from main below. Can anyone help? Thanks, Greg #include <boost/iterator_adaptors.hpp> #include <boost/shared_ptr.hpp> #include <vector> using namespace boost; using namespace std; struct Shape { virtual ~Shape() {} virtual void draw() const = 0; virtual void update() = 0; }; struct Concrete_shape : Shape { void draw() const {} void update() {} }; typedef shared_ptr<Shape> Shape_ptr; typedef shared_ptr<const Shape> Const_shape_ptr; struct Picture { typedef vector<Shape_ptr> Shapes; // Declare a const_iterator that converts // to the underlying Shape_ptr to a // Const_shape_ptr. Since the returned // Const_shape_ptr is a temporary, clients // shouldn't be allowed to modify it. typedef iterator_adaptor< Shapes::const_iterator, default_iterator_policies, value_type_is<Const_shape_ptr>, reference_is<const Const_shape_ptr>, iterator_category_is<input_iterator_tag> > const_iterator; const_iterator begin() const { return const_iterator(shapes_.begin()); } Shapes shapes_; }; int main(int argc, char* argv[]) { Picture pic; const Picture& cpic = pic; pic.shapes_.push_back(Shape_ptr(new Concrete_shape)); Picture::const_iterator i = cpic.begin(); // I'd like to prevent clients from writing... i->reset(new Concrete_shape); *i = Const_shape_ptr(new Concrete_shape); return 0; }

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Property Map deep copy
by Björn Lindberg 01 Nov '02

01 Nov '02

I have an external iterator_property_map to an adjacency_list, using std::vector to store std::string as values. I need to copy this map, but a deep copy so that all the strings are unique to the copy. Is there an easy way to do this? I thought about constructing a new property map from a copy of the underlying vector, but this presents two other questions: (i) will the vertex-to-string mappings of the old map still be valid in the constructed copy? (ii) is there a way to extract the underlying vector from the property map? I couldn't find information on this in the online documentation. Björn

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[BGL] How to prune a BFS or exit a BFS
by kweeheong 01 Nov '02

01 Nov '02

I have a custom BFS visitor used to traverse a graph. Is there a built-in way to - prune off a vertex's descendants from the search - exit a BFS These ( pruning and terminating ) are separate situations. I believe the following will work; however, I do not know how to access the relevant data structures. - To prune off a vertex's descendents from the search In the custom BFS visitor's discover_vertex event, set the color of all its adjacent descendants to "black". - To exit a BFS In the custom BFS visitor's discover_vertex event, once the required vertex is found, empty the queue of vertices. How can I access a vertex's color and a BFS's queue? Or is there a better way?

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How to pass result of boost::bind to arg of template function ?
by hugo duncan 31 Oct '02

31 Oct '02

Hi, I want to pass the result of a boost::bind as an argument of a templated function of a class, and am struggling to find a signature that will let me do this. Is this possible? if so what signature should the function have ? Any help much apreciated Hugo #include "boost/function/function1.hpp" #include "boost/bind.hpp" class another_class {}; class my_class { public: typedef another_class ObjectType; //! this works fine passing a boost::function object template <class ReturnType> void add(const boost::function1<ReturnType,ObjectType>& arg) { boost::function1<ReturnType,ObjectType> fn_obj=arg; } //! this should work when passed the result of a boost::bind template <class ReturnType> void add(?what goes here? & arg) { function1<ReturnType,ObjectType> fn_obj(arg); } }; int fn(another_class,int) { return 1; } int main(int, char**) { my_class c; c.add(boost::bind(&fn,_1,1)); }

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[bgl] breadth_first_search for shortest paths (fwd)
by Joel Young 31 Oct '02

31 Oct '02

Dear Jeremy, et al, I am trying to implement a shortest paths algorithm on a directed graph. As I have unit edge weights, I would rather use breadth_first_search rather than dijkstra. // Is this a good candidate for addition? template <class Map, class Tag> struct vertex_marker : public boost::base_visitor<vertex_marker<Map,Tag> > { typedef Tag event_filter; vertex_marker(Map p_map,int p_val) : m_map(p_map),m_val(p_val) { } template <class Vertex, class Graph> void operator()(Vertex v,const Graph&) { boost::put(m_map,v,m_val); } Map m_map; int m_val; }; template <class Map, class Tag> vertex_marker<Map,Tag> mark_vertices(Map p_map, Tag, int p_v) { return vertex_marker<Map,Tag>(p_map,p_v); } boost::breadth_first_search( mygraph, rootnode, boost::visitor(boost::make_bfs_visitor( std::make_pair( boost::record_distances( boost::get(boost::vertex_distance,mygraph), boost::on_tree_edge()) , std::make_pair( mark_vertices( boost::get(boost::vertex_distance,mygraph), boost::on_initialize_vertex(), std::numeric_limits<int>::max()) , mark_vertices( boost::get(boost::vertex_distance,mygraph), boost::on_start_vertex(), 0) ) ) )) ); The problem is that on_start_vertex does not seem to be implemented for breadth_first_search, but it is for depth_first. For dijkstra, the start node seems to be automaticly zeroed. I guess I could mod Am I missing something really obvious here or is there an inconsistency across the algorithms? Shouldn't on_start_vertex be used for all of the graph algorithms? Also, I can't seem to find documentation on neighbor_bfs.hpp Thanks, Joel

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