- Boost-users - lists.boost.org

[Multi-Index] find returning false positives?
by David Brownell 28 Dec '06

28 Dec '06

When comparing the results of the find method to the end iterator in the code below, it appears that find is finding elements that are not in the container. Am I using multi-index in the wrong way? Thanks for the help! #include <boost/multi_index_container.hpp> #include <boost/multi_index/sequenced_index.hpp> #include <boost/multi_index/ordered_index.hpp> #include <boost/shared_ptr.hpp> #include <iostream> struct MyObject : private boost::noncopyable { explicit MyObject(int i) : _i(i) {} int Get(void) const { return(_i); } bool operator <(MyObject const &rhs) const { return(_i < rhs._i); } private: int _i; }; typedef boost::shared_ptr<MyObject> MyObjectPtr; using namespace boost::multi_index; typedef multi_index_container<MyObjectPtr, indexed_by<sequenced<>, ordered_unique<identity<MyObject> > > > MyContainer; struct CompareFunc { bool operator()(MyObject const &o, int i) const { return(i == o.Get()); } bool operator()(int i, MyObject const &o) const { return(o.Get() == i); } }; int main(void) { MyContainer c; c.push_back(boost::shared_ptr<MyObject>(new MyObject(3))); c.push_back(boost::shared_ptr<MyObject>(new MyObject(4))); c.push_back(boost::shared_ptr<MyObject>(new MyObject(1))); MyContainer::nth_index<1>::type const & r = c.get<1>(); std::cout << (r.find(1, CompareFunc()) == r.end() ? "Not found" : "found") << "\n"; std::cout << (r.find(13, CompareFunc()) == r.end() ? "Not found" : "found") << "\n"; // This should not be found return(0); }

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[Boost.Threads] Exiting Thread Properly
by Soren Dreijer 28 Dec '06

28 Dec '06

Hi, I'm new to Boost.Threads and have previously been using Windows events to signal threads to shut down. Since the Boost.Threads library does not include an Event type I'm wondering what the best approach is to signal a thread to exit. Let's say the thread is a worker thread which loops around every time it has finished its job and then wants to determine if it should shut down or not. Thanks, Soren

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Boost::Timer does not tick
by Christoph 27 Dec '06

27 Dec '06

I've tried to use Boost::Timer together with Qt. However, the elapsed() function always does return the same value. I've found hints (see http://www.gerd-riesselmann.net/development/std-clock-threading-and-linux) that this might be related to the threading (used in Qt4). Is this a known issue? What is the suggested workaround (apart from using something else for timing? Best regards Christoph

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Re: [Boost-users] [Boost.Threads] Exiting Thread Properly
by Søren Dreijer 27 Dec '06

27 Dec '06

Ah, excellent! I seem to recall a post somewhere mentioning that relying on volatile might not always work on multiprocessor systems. Is that something to worry about?Quick follow-up question: Why do you use auto_ptr<bool> when passing the flag_guard to the thread when you release it right afterwards? Is there a chance that thread's constructor or bind() might throw an exception?Thanks for the quick response, Soren > Date: Wed, 27 Dec 2006 20:45:40 +0100> From: sebastian.redl(a)getdesigned.at> To: boost-users(a)lists.boost.org> Subject: Re: [Boost-users] [Boost.Threads] Exiting Thread Properly> > Soren Dreijer wrote:> > I'm wondering what the best approach is to signal a> > thread to exit.> Just allocate a boolean variable for each thread and pass the address to> the thread starting function. The loop of the thread breaks if the flag> is reset; the thread exits. This scheme is so simple that it doesn't> even require synchronization beyond making the pointer the thread> accesses volatile.> You could use a shared_ptr to manage the memory, but personally I would> simply use a scoped_ptr in the thread's main function.> The following code is conceptual. I can't remember the exact API of> Boost.Threads.> > void thread_proc(volatile bool *flag)> {> scoped_ptr<bool> guard(flag);> while(*flag) {> // Work> }> }> > map<threadid, bool *> flags;> > void create_worker()> {> auto_ptr<bool> flag_guard(new bool(true));> thread t(bind(&thread_proc, flag_guard.get()));> // Thread is started. This ensures that it will release the memory.> bool *b = flag_guard.release();> > flags.insert(make_pair(t.get_id(), b));> }> > // Note: this function needs to synchronize if you can't ensure that it> will only be ever called once> // for any given thread id.> void signal_worker(threadid id)> {> flag_iterator i = flags.find(id);> if(i != flags.end()) {> bool *b = i->second;> flags.remove(id);> *b = false;> }> }> > You will need to synchronize map access, of course.> > Sebastian Redl> _______________________________________________> Boost-users mailing list> Boost-users(a)lists.boost.org> http://lists.boost.org/mailman/listinfo.cgi/boost-users _________________________________________________________________ Call friends with PC-to-PC calling -- FREE http://get.live.com/messenger/overview

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Read-only access to boost repository via WinCVS
by alexmark 27 Dec '06

27 Dec '06

Hi! I need read-only access to boost repositiry. I've downloaded and installed WinCVS+Python but cannot open the repository. In Remote->Init Settings->CVSROOT I've checked it and entered: pserver:anonymous@boost.cvs.sourceforge.net:/cvsroot/boost and the response was: cvs -d pserver:anonymous@boost.cvs.sourceforge.net:/cvsroot/boost init cvs init: warning: unrecognized response `'ssh' is not recognized as an internal or external command, ' from cvs server cvs init: warning: unrecognized response `operable program or batch file. ' from cvs server cvs [init aborted]: end of file from server (consult above messages if any) What's wrong? TYA

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graph library: finding single-pair shortest path
by Matthew Reid 27 Dec '06

27 Dec '06

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Installation problems
by Yutaka Leon Suematsu 27 Dec '06

27 Dec '06

Hello Dear Boosters! Merry X'MAS and Happy New Year! I have some problems when installing the current version from cvs. I tried in Windows XP with VC++ 2003 and Python 2.5. * Command 1 C:\Source\boost>bjam -sTOOLS=vc-7_1 --with-python-version=2.5 --with- python-root=C:\Python25 --prefix="C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7" install * Result error: wrong library name 'python-version=2.5' in the --with- <library> option. ------- *Command 2 C:\Source\boost>bjam -sTOOLS=vc-7_1 --with-python-root=C:\Python25 -- with-python-version=2.5 --prefix="C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7" install *Result error: wrong library name 'python-root=C:\Python25' in the --with- <library> option. -------- * Command 3 ( Defining PYTHON_ROOT and PYTHON_VERSION) C:\Source\boost>bjam -sTOOLS=vc-7_1 --prefix="C:\Program Files \Microsoft Visual Studio .NET 2003\Vc7" install * Result The mpi module has not been initialized; MPI libraries will not be built. hint: add "using mpi ;" to user-config.jam to enable MPI support. warning: Python location is not configured warning: the Boost.Python library won't be built Building Boost.Regex with the optional Unicode/ICU support disabled. Please refer to the Boost.Regex documentation for more information (and if you don't know what ICU is then you probably don't need it). warning: No toolsets are configured. warning: Configuring default toolset "msvc". warning: If the default is wrong, you may not be able to build C++ programs. warning: Use the "--toolset=xxxxx" option to override our guess. warning: For more configuration options, please consult ECHO warning: http://boost.org/boost-build2/doc/html/bbv2/advanced/configuration.html -------- *** From this message, it can also be observed that even though "vc-7_1" was defined as toolset, bjam is using "msvc" I tried to install the same version in a Mac and problem is the same. Any ideas or fixes to this problem? I should notice that I am using the bjam (from source) obtained from the cvs version of boost Thank you in advance. Yutaka Leon Suematsu.

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proposal of type_traits extensions
by Daniel 26 Dec '06

26 Dec '06

Hello, I am looking for set of templates which will help while working with class member pointers. I am sending my wish list so you can tell if my suggestions are worth implementing or not: - is_const_member_function_pointer<T> - true_type for const member function pointers (e.g. void (Test::*)() const) (BTW, is is possible to check this using current version of type_traits library?); - is_member_pointer_of<T, TClass> - true_type if T is member pointer of class TClass; - add_membership<T, TClass> - make T a pointer to member of class TClass; - remove_membership<T> - convert T TClass::* to T, and also similarly for member function pointers; - get_membership<T> - for member pointers, return class type; - member_traits<T> - returns class name and type of member pointers (can be obtained sepately by member_of<T> and remove_membership<T>); - member_function_traits<T> - similar to function_traits, but should also return class name and if function is const; Also I am looking for template which can change 'pointer to member function' to 'pointer to const member function' and vice-versa. Daniel

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BOOST graph- shortest path which including a node set?
by Terence Wilson 26 Dec '06

26 Dec '06

What I need is a version of Dijkstra's shortest path where the path includes a specified set of nodes. Does this exist? TIA

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Re: [Boost-users] Spamming through boost???
by Ovanes Markarian 24 Dec '06

24 Dec '06

Well, I googled for my name and found on the first page an entry from the boost archive at Gmane: >From: Ovanes Markarian <om_boost <at> xxx.xxx> Subject: [mpl::map] pregeneration of ... Is there smth, that I miss? With Kind Regards, Ovanes Markarian. To parse the string: <om_boost <at> xxx.xxx> is really silly and can be easily done with your regex lib. With Kind Regards, Ovanes Markarian On Thu, December 7, 2006 10:31, John Maddock wrote: > Sebastian Redl wrote: >> Ovanes Markarian wrote: >>> Now I really think, there must be email servers inbetween, which simply log the sender and put them to the spamming lists. >> We had this discussion a few months ago. >> In short, the easiest way to get at your e-mail address is to simply register with the boost list, and then have a bot listening and collecting. It's pretty much the same thing that some list archives do. You can't really prevent it, either. Unlike spammers, such >> accounts don't really make their presence known. Should all accounts that just listen and never post be banned? > > In addition the Boost mailing list is available via a newsgroup bridge, and gets archived on the web, indexed by Google etc (although I confess a Google search for your address didn't show anything up). As Sebastian has already said, these spammers are cunning folks whow really will stop at nothing to get these addresses :-( > > You > > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users > With Kind Regards, Ovanes Markarian

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