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

Re: [Boost-users] Building Boost on Solaris 10.
by Markus Bernhardt 13 Jul '07

13 Jul '07

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi Sabyasachi, I'm using boost 1.34.0 on Solaris 10 with Sun Studio 11. In 1.34.0 building on Solaris is a little bit broken. You are using commands for 1.32.0. They are not working any more. See my attached stripped down Makefile. Haven't tested this stripped down version. Hope it works. 0. You need to have the following tools in $PATH - gpatch - gmake - gtar - CC 1. Unpack the tar-file. 2. copy boost_1_34_0.tar.gz to thirdparty/packages 3. cd thirdparty 4. gmake The generated binaries are 64-bit. If you want 32-bit binaries, remove the line: $(PATCH) -p1 < $(local_srcdir)/patches/$(BOOST).patch.$(ARCHCC) || exit 1; \ (2 occurrences !!!) I only build the libs: - - thread - - serialization - - filesystem If you need other libs add "--with-<libraryname>" everywhere, where you see "--with-thread" Kind regards, Markus - -- Software Consulting Markus Bernhardt GmbH Spieljochstr. 34 81825 München Fon: +49-89-420903-14 Fax: +49-89-420903-20 www: http://www.scmb.de Geschäftsführung Markus Bernhardt Handelsregister AG München HRB 125966 USt-Id DE201885231 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2.2 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFGlwlkdnooMonJSYkRAvBbAJwMzr6wTk1/qlrfMy4JAZ4vrEhJkACcCWKS cPjrOgAQwivsGSqPaBdD25Q= =YhTA -----END PGP SIGNATURE-----

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Apparent defect with boost::bind macro used for member function with boost::function
by Ben McCart 13 Jul '07

13 Jul '07

There appears to be a defect in bound_memfunc_ptr. This occurs when using boost::bind macro to bind an object with its class member function for use with the boost::function pointer. For example, when using boost::bind to bind an object and associated class member function to a pointer like this: class A { public: void some_function(int i){}; }; A a1; boost::function<void, int> pfa1; pfa1 = boost::bind(&A::some_function, &a1, _1); ...the bound_memfunc_ptr.memfunc_ptr is populated with the address of A::some_function. However, the bound_memfunc_ptr.obj_ptr apears to be uninitialized. (pfa1.functor.bound_memfunc_ptr.obj_ptr has an address of 0xcccccccc in MSVC 2005) The function pointer works just fine to make calls. Internally the functor is storing the address of a1. However the address of a1 is not exposed through the bound_memfunc_ptr interface. I have assumed that the obj_ptr member which is of type void* is supposed to be the address of a1. Since a1's address is not exposed, it is not possible to distinguish between boost::function pointers that point to a1's member some_function() and any other object of class A. With this condition boost::function is unsuitable for use in an observer design pattern since there is no way to distinguish which boost::function pointer points to an observer when an observer wants to remove itself (unsubscribe) from an event. So, does anybody have any recommendations? Is the obj_ptr member supposed to be what I think it is, or is it for another purpose? Is there any other way to get at the address of a bound object, so that the boost::function pointer can be uniquely identified? Thanks in advance, ~Ben

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[smart_ptr] Getting segfaults with weak_ptr<T>::lock()
by Buddha Buck 13 Jul '07

13 Jul '07

I've run into a problem where a weak_ptr<> is segfaulting when I try to do a lock() call on it. It doesn't happen all the time, and I'm at a loss to see what's causing the problem. I have an implementation of the Observer pattern in my code using shared_ptr/weak_ptr: class Observer { public: virtual void update(shared_ptr<Observed> d) = 0; ... } class Observed : public enable_shared_from_this<Observed> { vector<weak_ptr<Observer> > _observers; public: void register(shared_ptr<Observer> o) { _observers.push_back(weak_ptr<Observer>(o)); } void notifyObservers() { vector<weak_ptr<Observer> >::iterator i; for (i = _observers.begin(); i != _observers.end(); observer++) { shared_ptr<Observer> o = i->lock(); if (o) o->update(shared_from_this()); } } ... } I'm trying to write a wxWidget that participates in the above Observer scheme, but quickly ran into a problem: wxWidgets passes around raw pointers and handles its own garbage-collection. If I created a shared_ptr<MyWidget>, wx would feel perfectly free to delete the object out from under the shared_ptr<>, which would be bad. My solution was: template <typename T> class wxObserver : public Observer { private: T* p; wxObserver(); public: wxObserver(T* p) : p(p); void update(shared_ptr<Observed> o) { if (p) p->update(o); } } class MyWidget : public wxWidget { private: shared_ptr<wxObserver<MyWidget> > observer; public: MyWidget(...) : wxWidget(...), observer(this) { ... observed->register(observer); ... } ... } The idea is that when a MyWidget is created, it creates a shared pointer to a wxObserver and can register that wxObserver with observed objects without a problem. When wxWidgets chooses to delete the MyWidget, the shared pointer the MyWidget goes away, the wxObserver is deleted, and the weak pointers held by the observed objects expire. The implementation of Observed::notifyObservers() checks to make sure that the observers still exist before update()ing them, and only the live observers are updated. The problem is that sometimes, after wxWidgets destroys a MyWidget, calls to Observed::notifyObservers() crashes with a segfault within the call to i->lock(). I can't see what's causing this. Worse, while it crashes consistantly and repeatedly at the same line, it doesn't appear to always crash after the same amount of work. Putting various {cerr << "got here";}-type lines within the code above doesn't always yield exactly the same results from run to run, even without recompiling. My thoughts are now that it might be a threading issue. Is there any good solutions to this problem? thanks, Buddha

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Re: [Boost-users] Why does G++ have no auto-linking like VC?
by Olaf van der Spek 13 Jul '07

13 Jul '07

Hi, Why does G++ have no auto-linking like VC? And what is the recommended way to link to a Boost lib with g++ or make? Please CC me, I'm not on the list. Olaf

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[Graph] Maximum Cardinality Matching: weighted?
by Jean-Francois Bastien 12 Jul '07

12 Jul '07

Hello, I am just starting on using boost::graph and I would like to solve the following problem: I have a potentially unbalanced complete weighted bipartite graph and I would like to find the maximum weighted maximum cardinality matching for it. The immediate candidate for this seems to be the checked_edmonds_maximum_cardinality_matching. I realize that my graph is bipartite and that Edmond's algorithm is for general graph, but the graph library doesn't seem to have an algorithm optimized for bipartite graphs (please correct me if I'm wrong on this). My problem is this: in reading the documentation and the code I seem to understand that the implementation doesn't take into account the weight of the graphs. I'd like to know if it does take weights into account or not before I dive into learning the boost::graph library just to realize that it doesn't solve my problem. If the implementation doesn't take weights into account then is there another algorithm (or combination thereof) that I've overlooked from the library which could solve my problem? Sincerely, JF

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Suggestion for iterator_facade documentation
by Max Motovilov 12 Jul '07

12 Jul '07

It is not immediately obvious how to correctly specify the template arguments for boost::iterator_facade<> with an output iterator. This particular case is not mentioned in the tutorial and the first impression is that using such category as std::output_iterator_tag should be all that's required. This is not the case; in order for the postincrement temporary NOT to create a copy of a [fake] pointed-to value OR a copy of the proxy, the user has to be very careful about Value and Reference arguments. Took me 3 tries and a thorough look into the sources to get it right: Value=<argument of Proxy::operator=> and Reference=Proxy&. Would be nice to add this use case to the tutorial since it is definitely tricky and error-prone as it is. Of course there might be ANOTHER piece of documentation describing it that I missed :( Regards, ...Max...

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Re: [Boost-users] Question
by question boost 12 Jul '07

12 Jul '07

Hi Chun ping Wang, you seem to understand my problem. You say to run build.bat (see bjam.qbk), it's ok. Then you say to configure my environment. I've set the variables BOOST_ROOT and BOOST_BUILD_PATH but I get the message again. So I ask you what do you mean exactly by "configuring my environment"? Be very clear.(Step by step) Thank You Chun Ping Wang Date: Mon, 25 Jun 2007 07:49:14 -0700From: cablepuff(a)gmail.comTo: boost-users(a)lists.boost.orgSubject: Re: [Boost-users] QuestionYou need to build boost most likely with bjam. If your under windows go to tools/jam/src and type build.bat or if under unix ./build.sh and it should automatically build bjam.exe . You might need to configure your enviornment though. On 6/25/07, question boost <question.boost(a)hotmail.fr> wrote: Hi, using Code Blocks i get the folowing message.ld.exe "Cannot find -lboost_filesystem-mgw-mt-s-l_33_l"How and where can I get this file?Thank You Besoin d'un e-mail ? Créez gratuitement un compte Windows Live Hotmail et bénéficiez d'un filtre antiphishing gratuit ! Windows Live Hotmail_______________________________________________Boost-users mailing listBoost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users _________________________________________________________________ Besoin d'un e-mail ? Créez gratuitement un compte Windows Live Hotmail, plus sûr, plus simple et plus complet ! http://www.windowslive.fr/hotmail/default.asp

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[Boost.Graph] Property map of a bundled property
by Ewgenij Sokolovski 12 Jul '07

12 Jul '07

Nobody knows the answer?:) Am I the only one confronted with this question? I mean I could define a structure to include my distance and pass it as a bundled property but isn't that a rather unclean way to manage the problem? Cheers Ewgenij

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Re: [Boost-users] Building Boost on Solaris 10.
by Sabyasachi Nath 12 Jul '07

12 Jul '07

When using "--with-toolset=sun" it gives a message of unknown toolset. Whereas by using "--with-toolset=sunpro" it runs but giving the same problem. Thanks & Regards, Sabyasachi Nath Product Development Unit UshaComm India Pvt Ltd Emp Id 1295 WS 441 Tel: 9133-22812803/05/06 Mo: 919830622831 Extn 230 -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org]On Behalf Of Rene Rivera Sent: Wednesday, July 11, 2007 9:50 PM To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] Building Boost on Solaris 10. Sabyasachi Nath wrote: > I am new with Boost. I am facing the following problem while building Boost > 1.34.0. ... > ============ > -bash-3.00$ ./configure -- > prefix=/disk2/sabyasachi/Boost_1.34.0/Build/boost_1_34_0 --with-libraries=all ... > Can anybody please sort out what the problem is? Add a "--with-toolset=sun" to the configure. -- -- Grafik - Don't Assume Anything -- Redshift Software, Inc. - http://redshift-software.com -- rrivera/acm.org - grafik/redshift-software.com -- 102708583/icq - grafikrobot/aim - grafikrobot/yahoo _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Compressed socket iostream
by gyrotech＠freakinabox.com 12 Jul '07

12 Jul '07

I've been looking over the boost documentation, but I can find anything to help me create an iostream for a socket. Can anyone point me in the direction of a tutorial or such that could help?? I found some references to asio, which was merged with boost in 2005, but the iostreams documentation was last updated in 2004. Also, is it possible\easy to add one of the compressing streams (basic_zlib_compressor for example) to an output socket stream so all the data sent over that TCP connection is compressed?? And on top of all of this, how would I go about making a stream that, if it had a socket connection, would stream data over that, otherwise to a file, both with the aforementioned compression? Thanks in advance, GyroTech

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