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[Multi-Index] crash on invariant_() violation
by Neil Hunt 03 Apr '09

03 Apr '09

> > This is definitely going to break the container's invariants, yes. Key > modification has to be done via modify() so as to give the container a > chance to reindex elements. So if you are quite sure this is happening > try to remove the offending behavior; after this my bet is that the > invariant assertion will go away. Otherwise please get back here. > > Just weighing in here with a related question. But first to say: I find multi-index to be invaluable. So thanks for a great library. In my code, the objects I am indexing against are altered elsewhere, and then my index owning code is notified. At this point, the index owning code calls: index.modify( index_iterator, NoOperationFunctor() ); That is, on the assumption that the modify function has no knowledge of what changes the functor are making, it must re-evaluate all indices. Therefore, it doesn't matter if the change is made inside the modify function as long as modify is called. (So, this statement from above does not appear strictly true: "Key modification has to be done via modify() so as to give the container a chance to reindex elements.") Because (in my case) the change is made elsewhere, I am calling modify with a functor that does nothing. In my particular case, I can guarantee that change made elsewhere won't affect the index that I use to find the iterator to pass to modify. This may seem a weird scenario, but it also seems weird that I have to call modify with a no-op functor. Is it possible/desirable to add a simple update_indices( itor ) function? Neil

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question about using boost.function and boost.bind, V1.38
by Tan, Tom (Shanghai) 03 Apr '09

03 Apr '09

Can any one please explain to me why the former fails while the latter compilesThe definition: // usage in a ctor initialisation list ..., where m_button_monitor is of type ButtonMonitor, , m_button_monitor(boost::bind(boost::mem_fn(&CView::OnRun), this, ID_TOOLBUTTON_AUTO)) //definition 1 of ButtonMonitor that fails // the error message by MS VC9SP1: // error C2664: 'programmer_board::ButtonMonitor::ButtonMonitor(boost::function<Signatur e> &)' : //cannot convert parameter 1 from 'boost::_bi::bind_t<R,F,L>' to 'boost::function<Signature> &' // class ButtonMonitor { public: ButtonMonitor(boost::function<void()>& f) : m_f(f) { } void UpdateStatus(BUTTON_STATUS status) { m_f(); }; private: boost::function<void()>& m_f; }; //definition 2 of ButtonMonitor that works class ButtonMonitor { public: ButtonMonitor(const boost::function<void()>& f) : m_f(f) { } void UpdateStatus(BUTTON_STATUS status) { m_f(); }; private: const boost::function<void()>& m_f; }; Thanks,

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[Q] eliminating false memory leak reports
by V S P 03 Apr '09

03 Apr '09

Hello, I have a class (below), and MS memory leak detector reports a leak on ptr.reset I have redefined 'new' as follows: #define MYDEBUG_NEW new( _NORMAL_BLOCK, __FILE__, __LINE__) In another example, also below I have an _impl structure that is allocated and assign to typedef boost::shared_ptr<cmoney_impl_dtl> t_money_storage; My understanding is that it is a 'false' detection is that correct? In otherwords, in my thinking -- as long as I have assigned an object to boost::shared_ptr -- I do not have remember anything about it anymore. (using visual studio 2008, 32 bit) Another question, since I have all of my heap objects using boost::shared_ptr is there any free tool that I can use to verify that those things do not leak (as some of the are actually DB connections so it is important for them to get completely destroyed). Thank you in advance ---------------------------- template <typename TThrdData> struct CService_ThreadData:private boost::noncopyable { CService_ThreadData (void){}; ~CService_ThreadData (void){}; ///creates a new thread data object if does not exists //Call this from every thread to establish thread's data //manager object static TThrdData& getdata(void) { /* YES, using static variable in this case is safe, because it is in the 'global' scope and therefore is intialized before Main starts Otherwise, static variables are not thread safe */ if (ptr.get() == 0) { ptr.reset(new TThrdData()); } return (TThrdData&)(*ptr); } private: static boost::thread_specific_ptr<TThrdData> ptr; };//end of class -------------------------- cmoney_t::cmoney_t (void) :v(new cmoney_impl_dtl) { } -- V S P toreason(a)fastmail.fm -- http://www.fastmail.fm - Access your email from home and the web

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date_time question
by Amadeus W.M. 03 Apr '09

03 Apr '09

The program below reads a date from a string -> istringstream -> ptime. The string contains comma separated fields, the first of which is a date in the format %Y-%m-%d (without %H:%M:%S): 2009-04-03,12.34,56.78 If I define a facet with in the format %Y-%m-%d %H:%M:%S then the program outputs 2009-Apr-03 12:34:56 i.e. it interprets the numbers following the date as %H:%M:%S even though they are separated by commas and dots, rather than colons. Is this normal behaviour? Would it be possible to make it leave alone the fields following the date? That is, do not interpret 12.34,56.78 as %H:%M:%S. Thanks! // g++ -g -Wall -o dateIOSimgleFmt -I/usr/local/include/boost-1_38 dateIOSingleFmt.C #include <iostream> #include <sstream> #include <cstdlib> #include <string> #include <boost/date_time/posix_time/posix_time.hpp> using namespace std; using namespace boost::posix_time; int main(int argc, char * argv[]) { ptime pt(not_a_date_time); string datestr("2009-04-03,12.34,56.78"); const char * format="%Y-%m-%d %H:%M:%S"; istringstream INSTR(datestr); locale loc(INSTR.getloc(),new time_input_facet(format)); INSTR.imbue(loc); INSTR>>pt; cout << pt << endl; return 0; }

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[asio] Setting UDP Source Port
by Scott McMurray 03 Apr '09

03 Apr '09

I'm writing an application that makes use of the source port in the UDP header. The only way I've found that sets it is by setting the endpoint on construction of the udp::socket. The problem with that, however, is that I have 3 different components that want to use that port, one listening and two sending. Understandably, I cannot bind the same port for all three. (Incidentally, while binding with the udp::socket constructor works, the bind call gives a bad file descriptor exception. I'm using 1.35, though, so that may have been fixed.) Is there some way to set the source port without binding? Since there's no session state, it seems like I should be able to send packets from any number of sockets. (I can't just share a socket, as they're not shared-objects thread-safe, according to the documentation.) Thanks, ~ Scott McMurray

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Re: [Boost-users] [Multi-Index] crash on invariant_() violation
by Neil Hunt 03 Apr '09

03 Apr '09

> > ... it doesn't matter if the change is made inside the modify function > as long as modify is called. > > (So, this statement from above does not appear strictly true: > "Key modification has to be done via modify() so as to give the container a > chance to reindex elements.") > > Because (in my case) the change is made elsewhere, I am calling modify with > > a functor that does nothing. > I guess more generally, why is this paradigm implictly disallowed? index_itor->value++; index.update_indices( index_itor ); While I can see the benefit of tying the modification to the multi-index object via modify, there is no explicit reason that I can see why the above is invalid (as per my perfectly working code that uses this paradigm). And "forcing" the user to use a functor to modify can introduce annoying code overhead. Don't get me wrong, I think that using modify with a functor is very clear and helps prevent invalid indices. But, at the same time, it can be a pain to write a functor. (Here's to C++0x lambda's). But in my case, where the code that modifies the object is unaware of multi-indices on that object, it is not feasible to use modify() to make the change. Neil

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[serialization] Private default constructors
by Robert Dailey 03 Apr '09

03 Apr '09

I have a class that can be constructed statically in code, or constructed by data (this is where boost::serialization comes in). For example: class foo { public: foo() {} foo( std::string text ) : m_text( text ) {} private: template< class Archive > void serialize( Archive& archive, unsigned int version ) { archive & m_text; } std::string m_text; friend class boost::serialization::access; }; There is one problem with this, though. It is possible for a user of this class to create a "foo" with the default constructor, thus enabling them to have "zombie" objects. The only thing I want using the default constructor is boost::serialization, not the user. Is there a way I can make the default constructor private and still have boost::serialization access it? Keep in mind that this must work polymorphically too.

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[repost][filesystem][system] Linking errors with C++0X options on intel C++ 11.0
by jesseperla＠gmail.com 02 Apr '09

02 Apr '09

Sorry to repost, but I am at a loss and was hoping I have missed something. I am on Intel C++ 11.0 on windows. I built boost::filesystem and boost::system as static libraries with the following line in my userconfig.jam using intel-win : 11.0 : : <cxxflags>/Qstd:c++0x ; I am then compiling a project (that works with non-C++0x just fine) with /Qstd:c++0x in the command line. But when I try to link it with my calls to boost::filesystem header functions, I get the following link errors (it must be using auto linking) 1>etk_template.obj : error LNK2019: unresolved external symbol "class boost::system::error_category const & __cdecl boost::system::get_system_category(void)" (?get_system_category@system@boost@@YAABVerror_category@12@XZ) referenced in function _main 1>etk_template2.obj : error LNK2001: unresolved external symbol "class boost::system::error_category const & __cdecl boost::system::get_system_category(void)" (?get_system_category@system@boost@@YAABVerror_category@12@XZ) 1>etk_template.obj : error LNK2019: unresolved external symbol "class boost::system::error_category const & __cdecl boost::system::get_generic_category(void)" (?get_generic_category@system@boost@@YAABVerror_category@12@XZ) referenced in function _main 1>etk_template2.obj : error LNK2001: unresolved external symbol "class boost::system::error_category const & __cdecl boost::system::get_generic_category(void)" (?get_generic_category@system@boost@@YAABVerror_category@12@XZ) I am not changing any pre-compiler definitions for boost when I use /Qstd:c++0x. Should I be changing anything there? Am I out of luck? -Jesse

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[BGL] A bug in the edge_range() function.
by Michael Olea 02 Apr '09

02 Apr '09

In boost 1.37.0 there is a "metaprogramming bug" in the edge_range() function: it fails to compile when the Directed Selector template argument to adjacency_list is set to directedS, but does work if the argument is either undirectedS, or bidirectionalS. Attached below is a short program illustrating the problem. The problem is that edge_range() instantiates a StoredEdge via a constructor taking 3 arguments, but when the Directed Selector is directedS StoredEdge is typedef'ed to stored_edge_property<vertex_descriptor, EdgeProperty>, which has no such constructor. One solution might be to create overloaded edge_range_dispatch() functions, and dispatch on Config::on_edge_storage. -- Michael

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[serialization] Serializing "int" types...
by Robert Dailey 02 Apr '09

02 Apr '09

If I choose to serialize a variable with type "int", is this portable? For example, if I stream out this value on a 64-bit system, and then load it in on a 32-bit system, will this result in a buffer-overrun or anything else weird? I read the serialization docs but didn't see this topic in there. Sorry if I missed it. Help is appreciated. Thank you.

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[asio] async_accept shares port?
by Roman Shmelev 02 Apr '09

02 Apr '09

HI! I've got another strange question, hope it is not very dumb. I'm launching two programs on my computer. Each tcp_acceptor in each program calls async_accept on one port and so is ready to accept connections. When I try to connect to the predefined port, I am connecting to the app that called async_accept later. As I thought, when trying to listen to port that is already accepting connections - another program will receive some error_code, but I do not see this in my case. Where is the mistake? Thanks!

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[boost-users] lexical-cast throws exceptions
by Roman Shmelev 02 Apr '09

02 Apr '09

Please take a look at the simple piece of code. When it is compiled on MSVC 2008 (no sp) , Win Sp2 then we receive access violation on program exit Can you tell me the reason of such strange behaviour? (boost 1.38.0) #include "stdafx.h" #include <iostream> #include <boost/lexical_cast.hpp> //#include <boost/thread.hpp> using namespace std; class ctest { public: ~ctest () { boost::lexical_cast<string>(1); } }; ctest a; int main(int argc, char* argv[]) { boost::lexical_cast<string>(1); return 0; }

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[Multi-Index] crash on invariant_() violation
by Dominique Devienne 02 Apr '09

02 Apr '09

We've recently introduced a boost multi_index_container into our code base. Now another seemingly unrelated change triggers an invariant violation in the bmi code during a unit test. I've tried to look at what kind of invariant is checked in the code, but got lost in its intricacies... Could I please get some pointers on what I should specifically look for, and maybe what invariant violations could be triggered from (or have been in the past)? Assertion failed: invariant_(), file c:\...\boost-1.38.0-debug\boost\multi_index_container.hpp, line 683 I don't have all the details of the crash yet, but the invariant is violated either during a call to empty() on the implicit index of the container (a unique_hashed index), or a call to erase() on that same index. Note that the indices use BOOST_MULTI_INDEX_CONST_MEM_FUN on a proxy object, which extracts the indexed value on the proxy-wrapped pointer. It's quite possible our code base makes a change to one of the indexed value without notifying the bmi. Is this something that would trigger an invariant violation? (it's on my todo list to avoid having something like this happening). Any insights in troubleshooting the above would be appreciated. Thanks, --DD

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Re: [Boost-users] boost::array < pair<>... > iterator adaptor
by Hicham Mouline 02 Apr '09

02 Apr '09

>AMDG >Hicham Mouline wrote: >> I have a boost::array< pair<type1, type2>, maxsize > object, and I wish to >> iterate over the list of type1 elements, and the list of type2 elements... >> >> I gather I then need an iterator adaptor based on array's iterator and >> const_iterators... >> How may I write such a thing? >> >> I then can pass around iterators to type1 and type2 separately. >> >transform_iterator might be useful. I don't know off >the top of my head whether there is a more specialized >iterator adaptor in Boost somewhere. Great, this worked beautifully struct FirstElem : public std::unary_function< pair<>, double > { double operator()( const pair<>& p ) { return p.first; } }; typedef boost::transform_iterator< FirstElem, IterType > FirstElemIterType; FirstElemIterType feit ( container.begin() ); I can then pass feit around. Now, under normal assumptions, accessing first elements through feit should be as fast as direct access by manual loop.... inline calls should be optimized away? Thanks,

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boost::array and operator< on private type (which is a pair) for using std algos
by Hicham Mouline 02 Apr '09

02 Apr '09

Hello, I'm not sure this is specific about boost::array... I apologize if it is not boost specific. I have this code http://codepad.org/h9uFoI1I This compiles under g++4.0 1. I find it strange that it does given that EntryType is a __private__ type inside C<T1,T2>. 2. It doesn't do what I expect: my operator< is defined in std namespace but is never called (i did this because with std::pair comes < operators frm the std namespace) I don't want to define operator< for all pairs, just for contexts (member functions of C) which use EntryType. Is this because I typedef EntryType? rds,

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new idea for project
by divyanshu singh 02 Apr '09

02 Apr '09

HI all I am new to boost and i found its math function library really cool I like to play with numbers specially prime numbers I am thinking of developing a new library for boost that can generate various prime patterns adn will include other new algorithms related to prime numbers like aks algorithm to test whether a number is prime,Prime spiral algorithm,prime number generation algorithm This library can help people who love numbers and want to find new prime or number patterns first i would like to know that whether such library already exists in boost if not then hows the idea?

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Fusion usage: `at_c' is not a member of `boost::fusion'
by Mauricio Gomes 02 Apr '09

02 Apr '09

Hi, boost::fusion::vector<int> v(1); int x = boost::fusion::at_c<0>(v); This code is giving me the error: `at_c' is not a member of `boost::fusion'| The first line compiles fine. I have all the includes that are showed in fusion::vector documentation page. Which include (or anything else) am I missing ? Thank you for your attention, -- Mauricio Gomes Pensar Digital 55-11-8319-9610 (Brazil - mobile)

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[boost-users][bind, lambda] delayed assignment
by Igor R 02 Apr '09

02 Apr '09

Hello, I'd like to bild on-the-fly functor that would do something like: a_ = 1, b_ = 2; // a_, b_ - members But the assignment should be delayed until the functor is invoked. How can I do this with bind/lamda? Thanks!

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[Asio] Version correspondence?
by Rush Manbert 01 Apr '09

01 Apr '09

I'm trying to figure out which standalone Asio library versions correspond to the Boost library versions for: 1.35.0 1.36.0 1.37.0 1.38.0 Is it possible to discover this from the header files? Is there some other way? I'm adding Asio-based classes to an existing library. I think I want to try and implement them using the version that was in Boost 1.35.0, but I would like to give library users the option to use the Boost Asio or the corresponding stand-alone Asio. I expect some users would appreciate that. That's why I need to know what standalone Asio version to get. - Rush

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[Graph] Checking if a vertex_descriptor is valid
by Florian.PONROY＠fr.thalesgroup.com 01 Apr '09

01 Apr '09

Hi, I want to check if a vertex_descriptor is valid before using it. As I saw on this list, I perform the following test : Graph_t graph(10); vertexDescriptor srcVertex = boost::vertex(424242, graph); if (Graph_t::null_vertex() == boost::vertex(424242, graph)) { return; } Obviously, vertex indice 424242 does not exist, but test fails, and function does not return, leading the a crash of the following algorithm (BFS or Dijkstra). What did I do wrong? Thanks for your help. -- Florian PONROY Thales Land & Joint France Tel. : +33(0)1 41 304 363 Fax : +33(0)1 41 303 560 Email : florian.ponroy(a)fr.thalesgroup.com

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[interprocess] access dynamically accessed shared region in another process
by Stephan Menzel 01 Apr '09

01 Apr '09

Hi there, I'm trying to do IPC via boost.interprocess and use a dynamic buffer. This is on windows, debug mt, boost 1.38. To do this, I first create a shared segment and then a dynamic area in it. like this: struct transfer_buffer { void *buf; size_t bufsize; boost::interprocess::interprocess_mutex mutex; size_t dmember; } typedef boost::interprocess::managed_windows_shared_memory shared_segment; ... using namespace boost::interprocess; shared_memory_object::remove(bufname); struct transfer_buffer *ret = 0; shared_segment_ptr seg;// I use a ptr to store the object away so it won't get lost seg.reset(new shared_segment(create_only, bufname, begin_size)); // and our maintanance struct in it ret = seg->construct<struct transfer_buffer>(unique_instance)(); ret->dmember = 42; const std::size_t Alignment = 128; ret->bufsize = 1982781; ret->buf = seg->allocate_aligned(ret->bufsize, Alignment); Then, process A writes into the dynamic buffer, which seems to work OK. In the other process however, I try to open it and read the data. Like this: seg.reset(new shared_segment(open_only, bufname)); ret = seg->find<struct transfer_buffer>(unique_instance).first; Now I can access everything fine in ret (the struct itself), including the mutex and data members. But I cannot access the dynamically allocated buffer. As soon as I access it (read it, memcpy, anything) the app crashes with what would appear to be a rather broken callstack. When I look at the transfer_buffer struct before the crash it looks as if the dynamic pointer points to some inaccessable area. Not what I wrote in it anyway. Do I have to do anything else (other than creating the segment and find() the unique transfer_buffer struct) in the other process to access the dynamic area? Or is this a bug? Any help appreciated... Stephan

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boost::array < pair<>... > iterator adaptor
by Hicham Mouline 01 Apr '09

01 Apr '09

Hello, I have a boost::array< pair<type1, type2>, maxsize > object, and I wish to iterate over the list of type1 elements, and the list of type2 elements... I gather I then need an iterator adaptor based on array's iterator and const_iterators... How may I write such a thing? I then can pass around iterators to type1 and type2 separately. regards,

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move() aware containers?
by Noah Roberts 01 Apr '09

01 Apr '09

I'm reading a pre-release of a book on C++0x threading. I'm using the boost::thread library since it's supposed to be pretty close. Now they're using std::vector<> though and I know it's not move ready. Is there a boost container I can mimic this with?

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boost exception tutorial
by Robert Ramey 01 Apr '09

01 Apr '09

I'm investigating boost exception to see if it is helpful in a particular instance. I start by looking at the first Tutorial. I can't see how this is better than struc my_error : public std::exception { int m_ errno; my_error(int errno) : m_errno(errno) {} }; ... throw my_error(errno) try { ... } catch(my_error e){ cerr << e; } What am I missing here? This first example is two compilicated in that it requires that I delve into a bunch of other stuff (operator << for exception data?) and it doesn't provide any motivation. I think it would be more useful if it "spoon fed" the reader (me in this case) a little more. Something like: Traditional simple example like that above. explanation of why the example isn't "good enough" simple example reformulated using boost exception explanation of how this addresses the short comings of the original version. I think this would motivate more users to transition to the library. Robert Ramey

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Re: [Boost-users] [statechart] state behaviour
by Andreas Huber 01 Apr '09

01 Apr '09

> So, if I post an event and then execute "template< class > DestinationState > result transit();" in custom reaction this > destination state will be given posted event. Am I right? Yep. Regards, -- Andreas Huber When replying by private email, please remove the words spam and trap from the address shown in the header.

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