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But it would Re: [gil] [announcement] New IO lib
by Tom Brinkman 29 Apr '08

29 Apr '08

>> But it would introduce the dependency to boost::filesystem That would be a show-stopper for shur. I definately could not use your IO library if it had a boost::filesystem dependency. PLEASE - keep it header only.

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[shared_ptr] aliasing constructor mischief
by Frank Mori Hess 29 Apr '08

29 Apr '08

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 I've noticed it is possible to construct a half-empty shared_ptr that has an empty shared_count but a non-null pointer (brief example program attached). Perhaps the aliasing constructor, and similarly the shared_count constructor should do some argument checking? - -- Frank -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFIFxx05vihyNWuA4URApYiAJwMZIi0qKWDubA60c9yWyP8S5An2QCeK+es LAW09je97rpq4qxqTRqVuks= =h5d6 -----END PGP SIGNATURE-----

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[smart_ptr] questions about some regression test cases
by Daniel Frey 29 Apr '08

29 Apr '08

My questions result from the observation that in the virtual dtor of enable_shared_from_this, I tried BOOST_ASSERT( _shared_count.empty() ), but this makes 3 tests fail. Looking at these tests, I don't see why they should be legal: In esft_constructor_test.cpp, line 143, X initializes early_px by calling shared_from_this, but X is never passed to a shared_ptr which then owns it. From what I understand, this should be illegal. The next problem is esft_constructor_test.cpp, line 160. y.shared_from_this() returns a shared_ptr, but again, no shared_ptr takes ownership of Y later. While shared_from_this() is not called from the ctor, I wonder if this is yet another use case or just an accident. The test case in shared_from_this_test.cpp, line 135 is similar. Regards, Daniel

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Re: [boost] [1.35.1] Plans for 1.35.1?
by brass goowy 29 Apr '08

29 Apr '08

JOAQUIN M. LOPEZ MUÑOZ writes: >Hello, > >Are there any plans to release a 1.35.1 version? I'm interested in this also. If there isn't going to be a 1.35.1, I'll start downloading and building 1.35.0 now. I figured there was going to be a 1.35.1 a few weeks ago, but haven't heard anything definite. Also on this page, http://www.boost.org/community/, it says: "If you are looking for more lievely interaction with the Boost community there are also some internet relay chat channels that users and developers like to hang out in." I suggest changing that to: If you are looking for more lively interaction with the Boost community, there are some internet relay chat channels where users and developers like to hang out. Brian Wood Ebenezer Enterprises www.webEbenezer.net

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[tuple] Sorting tuples
by Stathi Triadis 28 Apr '08

28 Apr '08

Hi, I understand that the < operator is defined for tuples, but I'd like some kind of functor that can sort tuples in a different order; for example, the second, third, then first element of the tuple. Does boost already have something that does this? I was thinking something like this: template<uint First, uint Second, uint Third> struct SortTuple { template<typename Tuple> bool operator()(const Tuple& tup1, const Tuple& tup2) const { if (tuples::get<First>(tup1) != tuples::get<First>(tup2)) return tuples::get<First>(tup1) < tuples::get<First>(tup2); if (tuples::get<Second>(tup1) != tuples::get<Second>(tup2)) return tuples::get<Second>(tup1) < tuples::get<Second>(tup2); if (tuples::get<Third>(tup1) != tuples::get<Third>(tup2)) return tuples::get<Third>(tup1) < tuples::get<Third>(tup2); } }; typedef boost::tuple<int, int, int> MyTuple; vector<MyTuple> v; sort(v.begin(), v.end(), SortTuple<1, 2, 0>()); This was quite easy to implement, but what about an arbitrary number of tuple elements? Does this or something else with the equivalent functionality exist in boost? Cheers, Stathi

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[Concurrency] synchronized execution of concurrent component
by vicente.botet 28 Apr '08

28 Apr '08

Hi, I'm starting a library providing synchronized execution of objects, something like Ada 'rendez-vous'. A component Sender may request execution of a member function of a concurrent component Reveiver. The component Receiver must accept that the request can be fulfilled. Synchronized communication is described in a generic class concurrent_component. A concurrent_component defines the notion of a port for controlling the communication. A port has a nested entry class for defining operations controlled by the port; it also has an accept operation for signaling that an operation associated with the port can be executed. The concurrent_component and port classes interface will be the following: struct concurrent_component { class port { public: class entry_synchronizer { public: entry_synchronizer(port&); ~entry_synchronizer(); }; static void accept(port& p); }; }; In the following example, two concurrent components prod (Producer) and cons (Consumer) communicate via a single element buffer represented by a buf (SingleBuffer) concurrent component. The SingleBuffer class alternates between accepting a Push and a Pull: class SingleBuffer : concurrent_component { port PutPort_; port GetPort_; char bufCh_; public: void Put(char ch) { port::entry_synchronizer _(PutPort_); bufCh_ = ch; } char Get() { port::entry_synchronizer _(GetPort_); return bufCh_; } void operator()() { for(;;) { port::accept(PutPort_); port::accept(GetPort_); } } }; struct Producer : concurrent_component { SingleBuf& buf_; Producer(SingleBuf& buf) : buf_(buf) {} void operator()() { for(;;) { char ch; std::cin >> ch; buf_.Put(ch); } } }; struct Consumer : concurrent_component { SingleBuf& buf_; Consumer(SingleBuf& buf) : buf_(buf) {} void operator()() { for(;;) { char ch = buf_.Get(); std::cout << ch << std::endl; } } }; concurrent_component defines also a template class concurrent_execution<n> which is used to group the concurrent execution of n concurrent components. int main() { SingleBuffer buf; Producer prod(buf); Consumer cons(buf); concurrent_execution<3> conc(buf, prod, cons); conc.join_all(); return 0; } Other kind of ports can also be defined to restrict the instances that can do a request: * object_port which only accepts request from a given instance, or * qualified_port which only accepts request from instances of a given class. These classes can be extended allowing concurrent_component to open more that one port at the same time, and wait until all ports have been requested. class port { public: port(concurrent_component&); class entry_synchronizer { public: entry_synchronizer(port&); ~entry_synchronizer(); }; static void accept(port&); static void accept_all(port& p1, ..., port& pn); }; Do you think that this concurrent_component library could have a place in Boost? Best regards _____________________ Vicente Juan Botet Escriba

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Summer of Code 2008
by John Maddock 28 Apr '08

28 Apr '08

GSOC 2008 is on: http://code.google.com/soc/2008/ If folks have ideas for potential projects then now would be a good time to start thinking about them - that way we can apply to Google to be a mentoring organisation with a good selection of ideas already up and running. Cheers, John.

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Help with: BOOST_INSTALL_PROPERTY
by Shalmali Bodas 28 Apr '08

28 Apr '08

Hi, I am fairly new to the Boost Graph Libraries and am facing a problem in my code. I would appreciate your help with it. I have a program which already uses the BGL successfully. I just tried to implement as additional thing based on similar lines as existing code but the program gives me a "Segmentation Fault". [i am trying to define a New Custom vertex property called vertex_length ( in addition to earlier defined ones like vertex_coordinate_r,vertex_coordinate, vertex_depth) which gives distance from a root vertex to vertex under consideration] The.hpp contains: namespace boost { enum vertex_coordinate_t {vertex_coordinate = 1000}; enum vertex_coordinate_r_t {vertex_coordinate_r = 1001}; enum vertex_depth_t {vertex_depth = 1002}; enum vertex_length_t {vertex_length = 1003}; enum edge_generation_t {edge_generation = 1004}; BOOST_INSTALL_PROPERTY(vertex, coordinate); BOOST_INSTALL_PROPERTY(vertex, coordinate_r); BOOST_INSTALL_PROPERTY(vertex, depth); BOOST_INSTALL_PROPERTY(vertex, length); *// Line added by me* BOOST_INSTALL_PROPERTY(edge, generation); } typedef boost::property<boost::vertex_coordinate_t, Coordinate3D, boost::property<boost::vertex_coordinate_r_t, Coordinate3D, boost::property<boost::vertex_depth_t, int, boost::property<boost::vertex_length_t, int > > > > VertexProperty; typedef boost::property<boost::edge_generation_t, int> EdgeProperty; and later on inside a class: typedef boost::property_map<graph_t, boost::vertex_coordinate_t>::type v_coordinate_map_t; typedef boost::property_map<graph_t, boost::vertex_coordinate_r_t>::type v_coordinate_r_map_t; typedef boost::property_map<graph_t, boost::vertex_depth_t>::type v_depth_map_t; typedef boost::property_map<graph_t, boost::vertex_length_t>::type v_length_map_t; *// Line added by me* typedef boost::property_map<graph_t, boost::edge_generation_t>::type e_generation_map_t; ..............................................and so on.. While debugging, I have noticed that in the constructor - m_v_vertex_PROPERTY = boost::get(boost::vertex_PROPERTY, mygraph) where PROPERTY is either vertex_coordinate_r, vertex_coordinate, vertex_depth works well but does not work for vertex_length. When watched, the variable m_v_vertex_length gives "No symbol "m_v_vertex_length" in current context". I think there is problem in installing the property. What could be going wrong? Thanks for your help.

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Vault and sandbox
by Edward Diener 28 Apr '08

28 Apr '08

I do not understand what the difference is between software added to the Boost vault or software added to the Boost sandbox, Would someone please elucidate this for me. I know the sandbox resides under SVN, because I can use Tortoise SVN to update my local copy of it. Where does the Boost vault reside ?

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Idea for discussion: Putting version number in boost namespace?
by Jonathan Biggar 28 Apr '08

28 Apr '08

I noticed some discussion in threads about the worries that some people have with linking their application against boost and then needing a third party library that also links to a potentially different version of boost that might not be available to the in source form. Has any thought been given to changing the boost namespace declaration to include the version number, like this: namespace boost_1_35_0 { // boost libraries declared here }; #ifndef BOOST_NAMESPACE_ALIAS_DECLARED #define BOOST_NAMESPACE_ALIAS_DECLARED namespace boost = boost_1_35_0; #endif // BOOST_NAMESPACE_ALIAS_DECLARED This allows an application linked to boost 1.X+1.0 to also link to a third party library that privately uses boost 1.X.0 without causing ODR problems. Of course it doesn't help if the third party library exposes boost types in its interface. We could even go further and add another wrapper around the #ifndef/#endif above like this: #ifndef BOOST_NAKED_NAMESPACE #ifndef BOOST_NAMESPACE_ALIAS_DECLARED #define BOOST_NAMESPACE_ALIAS_DECLARED namespace boost = boost_1_35_0; #endif // BOOST_NAMESPACE_ALIAS_DECLARED #endif // BOOST_NAKED_NAMESPACE This allows an application to #define BOOST_NAKED_NAMESPACE and then use the versioned boost namespace directly. With care, it would be possible to write an application that used two versions of boost simultaneously, for example if that mythical third party library *did* expose boost types in its interface... -- Jon Biggar Floorboard Software jon(a)floorboard.com jon(a)biggar.org

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