- Boost-users - lists.boost.org

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?

2 1

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)

2 1

[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!

2 1

[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

1 0

[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

3 2

[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

3 5

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,

2 1

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?

2 2

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

5 7

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.

1 0