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enable_shared_from_this()
by Dominique Devienne 06 Feb '13

06 Feb '13

Can someone please explain why this code: struct Foo : boost::enable_shared_from_this<Foo> {}; Foo* p_foo = new Foo; boost::shared_ptr<Foo> ptr_foo(p_foo->shared_from_this()); is throwing? msvcr100d.dll!_CxxThrowException(void * pExceptionObject, const _s__ThrowInfo * pThrowInfo) Line 157 C++ boost::throw_exception<boost::bad_weak_ptr>(const boost::bad_weak_ptr & e) Line 61 + 0x4d bytes C++ boost::detail::shared_count::shared_count(const boost::detail::weak_count & r) Line 421 + 0x23 bytes C++ boost::shared_ptr<`anonymous namespace'::Foo>::shared_ptr<`anonymous namespace'::Foo><`anonymous namespace'::Foo>(const boost::weak_ptr<`anonymous namespace'::Foo> & r) Line 216 C++ boost::enable_shared_from_this<`anonymous namespace'::Foo>::shared_from_this() Line 49 + 0xf bytes C++ > `anonymous namespace'::test_method() Line 41 + 0xf bytes C++ Since Foo embeds a weak_ptr, why can't it new the pi_ on the spot? (I'm using Boost 1.44). Thanks, --DD PS: On a related note, why doesn't boost::shared_ptr<Foo>(p_foo) (where p_foo is a raw Foo*) implicitly apply the aliasing Ctor, to share the same px, to avoid the classic bug of having several different pn on the same px, since p_foo derives from enable_shared_from_this()? Initially i thought that's what sp_enable_shared_from_this() and pe->_internal_accept_owner() were meant to do, but obviously that's not the case.

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Boost statechart design question
by sidharth shanbhag 05 Feb '13

05 Feb '13

Hi, I am designing an application using Boost statechart and needed some advice. I have multiple objects of the same type/functionality, however they are not related by an inheritance heirachy. The class types have a defined initialization sequence which move from 1 state to another. A few of these state initialization steps are the same eg. Resource X should be initialized as the second step in the sequence. But X can be initialized only once in the process. I am looking at doing the following: - Creating a statechart for every object, to manage its initialization. - Each state machine will maintain the pointer of the class object it has initialized. - A map of object Name -> State Machine will be created to ensure every object is initialized correctly. - Represent resource X as a separate state, which after its initialization will transition to the next state. Is there a potentially better way to do this considering: - There can be multiple objects of different class types - New objects can be added during runtime. Thanks, Sid

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How can I free memory allocated when deserializing with boost::archive::text_iarchive
by Adlai Shawareb 05 Feb '13

05 Feb '13

Thanks for your reply. Here is a code sample: std::istringstream istr; <* put data into istr here *> boost::archive::text_iarchive ia(istr_); Message* p_temp; ia & p_temp; mpBaseIncomingMessage = p_temp; // mpBaseIncomingMessage is of type (Message *) mpIncomingMessage = static_cast<SystemMessage*>(mpBaseIncomingMessage); // mpIncomingMessage is a pointer to a class derived from Message mObjectCallbackMap.process(mpIncomingMessage->mEvent); // execute a callback for this event delete mpIncomingMessage; // delete the allocated memory We then see a crash on either the " mObjectCallbackMap.process..." line or the " delete mpIncomingMessage", but only when certain actions are taken by the system. Any thoughts would be greatly appreciated. Regards, Adlai -----Original Message----- From: Boost-users [mailto:boost-users-bounces@lists.boost.org] On Behalf Of boost-users-request(a)lists.boost.org Sent: Monday, February 04, 2013 1:11 PM To: boost-users(a)lists.boost.org Subject: Boost-users Digest, Vol 3349, Issue 6 Send Boost-users mailing list submissions to boost-users(a)lists.boost.org To subscribe or unsubscribe via the World Wide Web, visit http://lists.boost.org/mailman/listinfo.cgi/boost-users or, via email, send a message with subject or body 'help' to boost-users-request(a)lists.boost.org You can reach the person managing the list at boost-users-owner(a)lists.boost.org When replying, please edit your Subject line so it is more specific than "Re: Contents of Boost-users digest..." Today's Topics: 1. Re: Crediting the Work of Others (Bill Buklis) 2. How can I free memory allocated when deserializing with boost::archive::text_iarchive (Adlai Shawareb) 3. Re: in IOS, thread_info object is being destructed before the thread finishes executing (Nat Linden) 4. Re: Undirected version of dijkstra shortest path on directed graph. (Jeremiah Willcock) 5. Re: Crediting the Work of Others (Algocoders) 6. Re: How can I free memory allocated when deserializing with boost::archive::text_iarchive (Tim Moore) 7. [mpl::integral_c] Compiler Error with Visual Studio 2010 (Christian Henning) 8. Re: [mpl::integral_c] Compiler Error with Visual Studio 2010 (Nathan Crookston) ---------------------------------------------------------------------- Message: 1 Date: Mon, 04 Feb 2013 13:18:47 -0600 From: Bill Buklis <boostusr(a)pbjzone.com> To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] Crediting the Work of Others Message-ID: <51100997.1050909(a)pbjzone.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed On 2/1/2013 1:33 PM, Algocoders wrote: > Dave Abrahams <dave <at> boostpro.com> writes: > >> >> It has come to my attention that this book appears to use the work of >> others without attribution. I'd like to give the authors a chance to >> explain why that appearance is false. From what you can see in >> Amazon's limited preview of the book, one can find numerous instances >> of code lifted from Andrew Sutton's "origin" library. >> Some of the data structures have been renamed or had the case changed. >> Most of the duplication of Origin code comes in Chapter 7 in that >> book. There appear to be no references to Origin in that chapter >> (based on searching through the book in Amazon). >> >> The IndirectlyCopyable text includes unsourced quotes directly from >> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3351.pdf >> without quotation, and the concepts* diagrams are taken from the same >> document. Is there an attribution on the previous page that we can't >> see from Amazon's limited preview? > Crediting the work of others have been done in the book as mentioned > in the links below: > Preface : > http://www.algocoders.com/sites/default/files/preface_foa_revised.pdf > Acknowledgement : > http://www/algocoders.com/sites/default/files/acknowledgement_foa.pdf > Table of Contents : > http://www.algocoders.com/sites/default/files/toc_foa_revised.pdf > > Chapter 3 : > http://www.algocoders.com/sites/default/files/chapter3_foa.pdf > Chapter 11 : > http://www.algocoders.com/sites/default/files/chapter11_foa.pdf > > We have avoided repetitive mention of original sources in respective > chapters to let not the content be littered with these details again. > Please let us know if we need to attribute in respective chapters too, > we would like to work on it. > Your feedback will be really helpful to guide us as a corrective measure. > > Looking forward for suggestions, > > Cheers, > Algocoders > Only the last link for Chapter 11 actually works and there aren't any acknowledgements presented in that pdf. -- Bill ------------------------------ Message: 2 Date: Mon, 4 Feb 2013 19:46:54 +0000 From: Adlai Shawareb <adlai(a)vytronus.com> To: "boost-users(a)lists.boost.org" <boost-users(a)lists.boost.org> Subject: [Boost-users] How can I free memory allocated when deserializing with boost::archive::text_iarchive Message-ID: <842DD0CD91745A48B9355924E2CF0BEA114FEF3D(a)VYTRONUS-SBS.vytronus.local> Content-Type: text/plain; charset="us-ascii" Hi, Does anyone know how we can free memory that is dynamically allocated by boost::archive::text_iarchive when deserializing an archive? We have tried using 'delete' and free() on the pointer when we finish with it, but it results in a crash. How does Boost dynamically allocate memory, 'new', 'malloc', or other? We tried a shared_ptr, but were getting compile errors related to the include files, and have not gone back to track that down. So if there is a simple way to free the memory that would be best for our application. Thanks, Adlai Shawareb Vytronus, Inc.

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Boost 1.53.0 released!
by Marshall Clow 04 Feb '13

04 Feb '13

Release 1.53.0 of the Boost C++ Libraries is now available. These open-source libraries work well with the C++ Standard Library, and are usable across a broad spectrum of applications. The Boost license encourages both commercial and non-commercial use. This release contains five new libraries and numerous enhancements and bug fixes for existing libraries. New Libraries: * Atomic: C++11-style atomic<>, from Helge Bahmann, maintained by Tim Blechmann. * Coroutine: Coroutine library, from Oliver Kowalke. * Lockfree: Lockfree data structures, from Tim Blechmann. * Multiprecision: Extended precision arithmetic types for floating point, integer and rational arithmetic from John Maddock and Christopher Kormanyos. * Odeint: Solving ordinary differential equations, from Karsten Ahnert and Mario Mulansky. For details, including download links, see http://www.boost.org/users/news/version_1.53.0 You can also download directly from SourceForge: http://sourceforge.net/projects/boost/files/boost/1.53.0/ To install this release on your system, see http://www.boost.org/doc/libs/release/more/getting_started/index.html Thanks, --The Boost release team Beman Dawes Daniel James Eric Niebler Marshall Clow Rene Rivera Vladimir Prus

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[mpl::integral_c] Compiler Error with Visual Studio 2010
by Christian Henning 04 Feb '13

04 Feb '13

Hi there, shouldn't the following work: #include <boost\gil\gil_all.hpp> using namespace std; using namespace boost; int main() { typedef mpl::integral_c< unsigned char , numeric_limits< unsigned char >::max() > my_max_value_t; return 0; } Visual Studio 2010 gives me: error C2975: 'N' : invalid template argument for 'boost::mpl::integral_c', expected compile-time constant expression I'm a little surprised that this isn't working. Thanks, Christian

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How can I free memory allocated when deserializing with boost::archive::text_iarchive
by Adlai Shawareb 04 Feb '13

04 Feb '13

Hi, Does anyone know how we can free memory that is dynamically allocated by boost::archive::text_iarchive when deserializing an archive? We have tried using 'delete' and free() on the pointer when we finish with it, but it results in a crash. How does Boost dynamically allocate memory, 'new', 'malloc', or other? We tried a shared_ptr, but were getting compile errors related to the include files, and have not gone back to track that down. So if there is a simple way to free the memory that would be best for our application. Thanks, Adlai Shawareb Vytronus, Inc.

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A cool book for c++11 is Published now (Revised Edition)
by Algocoders . 04 Feb '13

04 Feb '13

Hi All, Revised edition of the book : "Foundation of Algorithms in C++11, Volume 1(Revised Edition): Using and Extending C++11, Boost And Beyond" : is available now. @Amazon: http://www.amazon.com/Foundation-Algorithms-Volume-Revised-Edition/dp/14819… @Pothi.com (Indian Edition): http://pothi.com/pothi/book/chandra-shekhar-kumar-foundation-algorithms-c11… This book is vital to understand and extend the C++11 Algorithms by carefully worked out synthesis of language and library features with an eye at future evolution with special emphasis to : - Template Alias - constexpr - copy_backward - requires - std::enable_if : SFINAE - Private Cast - Type Functions - Type Traits - Explicit Template Instantiations and Specializations - Trailing Return Type - auto type specifier - Intermediate Traits Idiom - Value Type Deduction Framework Table of Contents : http://algocoders.com/sites/default/files/toc_foa_revised.pdf Sample Chapter : http://algocoders.com/sites/default/files/chapter1_foa_revised.pdf For more details, please visit the link : http://www.algocoders.com/article/books Have Fun ! Cheers, Algocoders http://www.algocoders.com

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Undirected version of dijkstra shortest path on directed graph.
by Jupp Tscheak 04 Feb '13

04 Feb '13

Hello BGL specialists. Is it possible to use an undirected version of dijkstra shortest path function on an /adjacency_list/ which /Directed/ template parameter is set to bidirectional? Thanks in advance :)

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in IOS, thread_info object is being destructed before the thread finishes executing
by Andy Weinstein 04 Feb '13

04 Feb '13

Our project uses a few boost 1.48 libraries on several platforms, including Windows, Mac, Android, and IOS. We are able to consistently get the IOS version of the project to crash (nontrivially but reliably) when using IOS, and from our investigation we see that ~thread_data_base is being called on the thread's thread_info while its thread is still running. This seems to happen as a result of the smart pointer reaching a zero count, even though it is obviously still in scope in the thread_proxy function which creates it and runs the requested function in the thread. This seems to happen in various cases - the call stack is not identical between crashes, though there are a few variations which are common. Just to be clear - this often requires running code which is creating hundreds of threads, though there are never more than about 30 running simultaneously. I have "been lucky" and got it very very early in the run also, but that's rare. I created a version of the destructor which actually catches the code red-handed: in libs/thread/src/pthread/thread.cpp: thread_data_base::~thread_data_base() { boost::detail::thread_data_base* const thread_info=detail::get_current_thread_data(); void *void_thread_info = (void *) thread_info; void *void_this = (void *) this; // is somebody destructing the thread_data other than its own thread? // (remember that its own which should no longer point to it anyway, // because of the call to detail::set_current_thread_data(0) in thread_proxy) if (void_thread_info) { // == void_this) { __builtin_trap(); } } I should note that (as seen from the commented-out code) I had previously checked to see that void_thread_info == void_this because I was only checking for the case where the thread's current thread_info was killing itself. I have also seen cases where the value returned by get_current_thread_data is non-zero and different from "this", which is really weird. Also when I first wrote that version of the code, I wrote: if (((void*)thread_info) == ((void*)this)) and at run-time I got some very weird exception that said I something about a virtual function table or something like that - I don't remember. I decided that it was trying to call "==" for this object type and was unhappy with that, so I rewrote as above, putting the conversions to void * as separate lines of code. That in itself is quite suspicious to me. I am not one to run to rush to blame compilers, but... I should also note that when we did catch this happening the trap, we saw the destructor for ~shared_count appear twice consecutively on the stack in Xcode source. Very doubleweird. We tried to look at the disassembly, but couldn't make much out of it. Again - it looks like this is always a result of the shared_count which seems to be owned by the shared_ptr which owns the thread_info reaching zero too early. Help! Thanks, Andy Weinstein PS I cannot say for sure yet whether this problem occurs on the other platforms, though it looks like Windows is more solid that Mac. Android pretty solid also, though maybe in between Windows and Mac.

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Question regarding circular buffer usage
by Salivar.William 04 Feb '13

04 Feb '13

I am using the circular buffer container to hold up to 10000 std string objects. I am finding that once the buffer has reached max capacity, memory continues to be consumed as I push new strings in. Is there something I'm missing? I stepped into the boost code and it does make a copy of the string using the std string operator so I would think it handles the string copy properly. The size of the strings are variable but I would expect the memory usage to be fairly stable when the buffer is full but that is not the case. Here's basic usage Definition: boost::circular_buffer<std::string> m_message_buffer; Initialization: m_message_buffer.set_capacity (10000); Usage: void myClass::writeToBuffer (const char *message) { m_message_buffer.push_back (string (message)); } Boost code: void push_back(param_value_type item = value_type()) { if (full()) { if (empty()) return; replace(m_last, item); increment(m_last); m_first = m_last; } else { m_alloc.construct(m_last, item); increment(m_last); ++m_size; } } void replace(pointer pos, param_value_type item) { *pos = item; #if BOOST_CB_ENABLE_DEBUG invalidate_iterators(iterator(this, pos)); #endif }

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