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bjam in 1.44 vs 1.39
by Jonathan Brannan 04 Nov '10

04 Nov '10

We recently switched from boost 1.39 to boost 1.44. We use the bjam and boost build packaged with the version of boost we use. It seems that the bjam packaged with 1.44 exists with 0 even if there is a failure: ...failed gcc.compile.c++ /home/foo/Foo.o... ...failed updating 1 target... machine:/home/foo # echo $? 0 It stops early with the -q and prints out that it failed, it just exits 0. bjam -v Boost.Jam Version 3.1.18. OS=LINUX. Copyright 1993-2002 Christopher Seiwald and Perforce Software, Inc. Copyright 2001 David Turner. Copyright 2001-2004 David Abrahams. Copyright 2002-2008 Rene Rivera. Copyright 2003-2008 Vladimir Prus. With Version 3.1.17. OS=LINUX version that came with 1.39, I get an exit status of 1, which is what I expect.

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[mpl] Iterator Concept Checking?
by Stirling Westrup 04 Nov '10

04 Nov '10

I am writing some algorithms to operate on MPL sequences, and I would like to use some form of concept checking to ensure that the types passed in that are supposed to be iterators are, in fact, iterators. The MPL library doesn't seem to have is_XXX_iterator<T> checks, and I have run into some difficulties in determining how to write them. The MPL documents state that a random_access_iterator is a 'refinement' of a bidirectional_iterator which is a 'refinement' of a forward_iterator, but its not clear what refinement means in this context. I initially assumed that this meant that a random_access_iterator_tag was derived from a bidirectional_iterator_tag which was derived from a forward_iterator_tag. This does not appear to be the case, so the obvious test for an iterator (checking that the class contains a member named 'category' that is a type derived from the iterator tag of the least acceptable iterator) will not work. I am sure I could cobble together something that would work by examining the internals of the library, but I would far rather have some guidance on the correct way to see if an iterator matches a given iterator model, within the API of the library. Does anyone have any suggestions? -- Stirling Westrup Programmer, Entrepreneur. https://www.linkedin.com/e/fpf/77228 http://www.linkedin.com/in/swestrup http://technaut.livejournal.com

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boost::recursive_mutex doesn't lock ???
by Chris 03 Nov '10

03 Nov '10

Hello. I have a question about mutexes: Scenario 1: (OK) int main() { boost::mutex io_mutex; io_mutex.lock(); // thread will be blocked now boost::mutex::scoped_lock lock(io_mutex); cout << "Test" // this statement is not executed: OK } So far no problem, but if I use recursive_mutex instead... Scenario 2: (NOT OK) int main() { boost::recursive_mutex io_mutex; io_mutex.lock(); // thread will NOT be blocked ??? boost::recursive_mutex::scoped_lock lock(io_mutex); cout << "Test" // this statement is executed ??? } no blocking occurs?? I tried with unique_lock instead of scoped_lock but still no blocking Why not? I don't understand. How does one lock a recursive_mutex then? thank you Chris

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[Any] Operator ==
by Hossein Haeri 03 Nov '10

03 Nov '10

Dear all, Is there any way to implement an operator == (and perhaps also operator !=) for objects of type boost::any so that different instances are always != and an instance is always only == to itself -- regardless of the respective values? In case you're wondering why I'd interested in such operators, the answer is that I'm thinking of storing objects of type boost::any in an unordered_map. So, it would be equivalently helpful if you could provide a function object to be sent as the Pred template parameter to boost::unordered_map. TIA, --Hossein

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[asio] Removing server socket from service
by Sakharuk, Vladimir 03 Nov '10

03 Nov '10

I have one thread how runs io_service. I have 2 servers (tcp) ports with all corresponded acceptor and bunch of sockets connected to both ports. I am looking into the way to stop just one server but still run the other one. I have implemented a "hard" way to stop server: remove acceptor, cancel/close sockets, that will trigger all read/write asynchronous callbacks, wait till they all done. but there is a incontinence I need to know how may callbacks still here. Is there any simpler way to do the same thing? Something like block the cancel call until all call back done? Please follow the attached hyperlink to an important disclosure: http://www.credit-suisse.com/legal/marketcommentary =============================================================================== Please access the attached hyperlink for an important electronic communications disclaimer: http://www.credit-suisse.com/legal/en/disclaimer_email_ib.html ===============================================================================

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[range] multiple adaptors on sequense
by Sam Fisher 03 Nov '10

03 Nov '10

Hello, Is it possible to apply multiple adaptors to a range-base sequence? Is looks like possible for simple types: #include <string> #include <vector> #include <boost/shared_ptr.hpp> #include <boost/make_shared.hpp> #include <boost/range/algorithm_ext/push_back.hpp> #include <boost/range/adaptor/uniqued.hpp> #include <boost/range/adaptor/transformed.hpp> #include <boost/assign.hpp> using boost::assign::operator +=; #include <boost/spirit/home/phoenix.hpp> namespace phx = boost::phoenix; int square(int val) { return val * val; } int range_test_simple() { typedef std::vector<int> V; V source; source += 1,1,1,2,2,2,3,3,3,4; using namespace boost::adaptors; V result; boost::push_back(result, source | transformed(&square)); // Ok boost::push_back(result, source | uniqued); // Ok boost::push_back(result, source | transformed(&square) | uniqued); // Ok boost::push_back(result, source | uniqued | transformed(&square)); // Ok return 0; } but how about this? (source is continued...) struct Foo { Foo(const std::string& name, int value) : name_(name), value_(value) { } std::string name_; int value_; }; typedef boost::shared_ptr<Foo> FooPtr; int range_test_complex() { typedef std::vector<FooPtr> V; V source; source += boost::make_shared<Foo>("Foo", 10), boost::make_shared<Foo>("Bar", 20), boost::make_shared<Foo>("Baz", 30), boost::make_shared<Foo>("Baz", 30) // duplicate is here ; std::vector<std::string> result1; std::vector<int> result2; using namespace boost::adaptors; using phx::arg_names::arg1; boost::push_back(result1, source | transformed(phx::bind(&Foo::name_, *arg1)) | uniqued); // Fails boost::push_back(result2, source | transformed(phx::bind(&Foo::value_, *arg1)) | uniqued); // Fails return 0; } What I'm doing wrong? I use MSVS 2010 and boost trunk. Thanks, Sam

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Managing pipelines?
by Olivier Tournaire 03 Nov '10

03 Nov '10

Hi all, I am currently thinking on how to handle pipelines in some of my application. By pipeline, I mean "something" in which I can set an input, add some processing on that input, and retrieve the output (the result of the processing). If I am not clear enough, let's go with an example. Suppose I have an image, and I want first to crop it, then apply a filter on the crop and get the result in another image. Does boost has a library with such a feature? Best regards, Olivier ----------------------------------------------------- Olivier Tournaire MATIS - Institut Géographique National 73, Ave de Paris 94165 St Mandé cedex, France tel: (+33) 1 43 98 84 29 fax: (+33) 1 43 98 85 81

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Re: [Boost-users] Boost-users Digest, Vol 2531, Issue 1
by Dhirendra Pal Singh 03 Nov '10

03 Nov '10

> > On Tue, Nov 2, 2010 at 10:06 AM, Dhirendra Pal Singh <s9_rose(a)yahoo.com> > wrote: > > Hi Folks, > > If this question has been asked already, I apologise, > but I have to go back to my group and present the answer. So > please bear with me. > > > > In my current project we are using boost extensively, > with exceptions disabled, until last week, when I started > using boost threads. I get the following error when > compiling... > > > > *************** > > > deepsin@deepsin-lnx01:~/code/boost_thread/boost_threads_eg1$ > g++ -fno-exceptions -g -I /usr/local/include/boost/ t1.cpp > -o t1 -lboost_thread > > In file included from > /usr/local/include/boost/exception_ptr.hpp:9, > > ? ? ? ? ? ? ? ? from > /usr/local/include/boost/thread/future.hpp:14, > > ? ? ? ? ? ? ? ? from > /usr/local/include/boost/thread.hpp:24, > > ? ? ? ? ? ? ? ? from t1.cpp:3: > > > /usr/local/include/boost/exception/detail/exception_ptr.hpp:17:2: > error: #error This header requires exception handling to be > enabled. > > ************** > > > > This means that any header file that includes, > thread.hpp can't be compiled with -fno-exceptions. I have > couple of questions if someone could help me with, I would > appreciate. > > It appears that this is due to a dependency of Boost Thread > on Boost > Exception's exception_ptr. Somebody should look into this > and either > remove that dependency or add #ifndef BOOST_NO_EXCEPTIONS > around the > relevant code (unfortunately I don't have time right now to > look into > this myself.) > > Emil Dotchevski > Reverge Studios, Inc. > http://www.revergestudios.com/reblog/index.php?n=ReCode > Thanks for a response Emil. Do you think you can spare some time for hand holding, so that I can make this change... :) Thanks PS: I love this link on your webpage. http://www.revergestudios.com/reblog/uploads/ReCode/languages1.jpg. Everybody in my group got a kick out of it.

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Polymorphic serialization with polymorphic archives problems... [part 2]
by Bogdan 03 Nov '10

03 Nov '10

First I would like to confirm I tested Robert Ramey's fix (@60273) for multiple registrations and it looks good in my runs. Thank you Robert! On the other hand, I am under the impression there is a bug in void_caster::recursive_unregister(), although I am not 100% certain about the reason: that function member is called in the destructors of the void caster template classes and makes use of the void_caster_registry singleton (more specifically the type_set). I believe it searches the set for all the void caster entries that are descendants of the current one (i.e., the one being destroyed) and performs the following ops: - delete the shortcuts. - remove the corresponding entries from the set. However, void_caster::recursive_unregister() DOESN'T REMOVE FROM THE REGISTRAR the entry corresponding to the current void_caster(). This creates the problem below: consider a scenario where a dll containing some serialization functionality is loaded explicitly at runtime (i.e., using LoadLibrary() on Windows or dlopen on Unix). There are no parent-child relationships among the serialized classes registered by that DLL: all serialized classes are derived from one abstract base. While unloading the library, its void_caster singletons are destroyed but there are no shortcuts to remove from the global registrar since there are no parent-child relationships. All entries corresponding to those are still in the global registrar and POINT TO THE void_caster SINGLETONS ALREADY DESTROYED AND DISCARDED. When the main process exits, the registrar traversal repeats for whatever process-bound void_caster singletons are about to be destroyed. During these subsequent traversals, void_caster::recursive_unregister() visits the entries left after the previous explicit dll download and tries to identify the parent-child relationship. In doing so, it accesses the dangling vc pointers generating access violations: void_cast.cpp(Line 286): const void_caster * vc = *it; void_cast.cpp(Line 287): if(vc->m_parent == this){ //<--------------------- here is the access violation I can reproduce the crash systematically, but I am not sure about the reason or whether a simple unregistration is enough. I believe this is (again) a question for Robert, but I thank for any feedback I might get. Bogdan

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[Graph] how to find all shortest paths (not just one of them)?
by Erik Sjölund 03 Nov '10

03 Nov '10

Hi, I managed to record a shortest path between two vertices by doing adjacency_list < vecS, vecS, undirectedS > g; std::vector<Vertex> p(boost::num_vertices(g)); Vertex vertex = *(boost::vertices(g).first); boost::breadth_first_search(g, vertex, boost::visitor( boost::make_bfs_visitor( boost::record_predecessors(&p[0], boost::on_tree_edge()) ) ) ); The shortest path can be found by inspecting the vector p. But my goal is slightly different. Does anyone know how to "record" all shortest paths between two vertices? (i.e. all paths having the minimal path length) cheers, Erik Sjölund

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