June 2007 - Boost-users - lists.preview.boost.org

[serialization]
by Manuel Jung 18 Jun '07

18 Jun '07

Hi, I still got some starting problems with the boost::serialization library. I want to serialize a shared_ptr to my own polymorphic class. I'm building my own networkprotocol and the basic idea is a kind of "header"-class which with a shared_ptr<data_base> which can point to a lot of different data structs, which are polymorphic children of data_base. This "header"-class is then serialized and send to another peer. But how should this peer get the real type from the shared_ptr<data_base>? Which child is it pointing to? I can get the name with "typeid()", but i cannot get the type through that way. I would like to get the type from it automaticly without using some case-conditions, so i only have to add a new child of data_base and can use it, without changing any networkprotocol related code. Kind Regards Manuel Jung

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How to create a timer in boost::thread
by Meryl Silverburgh 18 Jun '07

18 Jun '07

Hi, Can you please tell me if i can do this with boost::thread library? 1. create a timer (say 5 seconds) which execute a function in a different thread when it expires. 2. the creator can cancel the timer before it expires. Thank you.

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BGL python bindings: copy.copy(g) adds spurious properties
by John Reid 18 Jun '07

18 Jun '07

Hi, When a graph is copied via copy.copy(g), extra vertex and edge property maps are added. import boost.graph as bgl g = bgl.Graph() prop = g.add_vertex_property('prop') from copy import copy g_copy = copy(g) print g.vertex_properties.keys() print g_copy.vertex_properties.keys() Output: g's vertex properties: ['prop'] g_copy's vertex properties: ['object', 'prop'] This property named 'object' contains the same values as the 'prop' property. Is this a bug in the pickling support? I have the latest version from SVN. Thanks, John.

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Can i compile Regex with _UNICODE/UNICODE instead of _MBCS under VC++6 ?
by alovespring＠gmail.com 18 Jun '07

18 Jun '07

thx!

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[boost] build of boost 1.34.0 with STLport
by LoadCom 18 Jun '07

18 Jun '07

hello, I downloaded the new boost 1.34 and try to build it. I found the doc of the new release have been improved a lot. But still with one thing I'm confused - with version 1.33.1, I can build the libs using VC6, VC7.1 or VC8.0 with different toolset files, and I also can use seperate toolset files if I want to build with STLport. In 1.34, I found only a msvc.jam and there's no STLport counterpart. Can anybody give me an explanation on this and tell me how to make a STLport build? I'm using MSVC7.1 on Windows XP. Thanks in advance. -------------- LoadCom 2007-06-16

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how to get local ip address using boost::asio
by Sergey Nikulov 18 Jun '07

18 Jun '07

Hi All, I'm looking for possibility to get my local ip address (not loopback) using boost::asio. Is it possible? I'm trying to use local_address_ = socket_.local_endpoint().address(); right after I connect to remote server, but it always return "127.0.0.1" as result. Could you please point me to information how to get address of my network card? Thank you.

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hidden directories
by Jacky J 17 Jun '07

17 Jun '07

How do i create hidden directories with the boost filesystem in linux? if i call create_directory(".test"), it gives me an error Thanks

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[pointer container] How to avoid double allocation?
by Seweryn Habdank-Wojewódzki 17 Jun '07

17 Jun '07

HI! Is there any opportunity, to avoid double allocation of memory using pointer containers? I have simple code (below) and I want allocate memory for objects, construct them, and _move_ (transfer) pointer to the container. Valgrind shows me that there are made 2 alocations even if I am creating only 1 object. ==20121== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 7 from 1) ==20121== malloc/free: in use at exit: 0 bytes in 0 blocks. ==20121== malloc/free: 2 allocs, 2 frees, 8 bytes allocated. What is happening If the object is huge? Is there any way to transfer the pointer? Regards. #include <boost/ptr_container/ptr_vector.hpp> class Foo { public: Foo (int const i) : i_ (i) {} private: int i_; }; Foo * ret_ptr(int const i) { return new Foo(i); } int main() { boost::ptr_vector<Foo> vfoo; for (int i = 0; i < 1; ++i) vfoo.push_back (ret_ptr(i)); } -- |\/\/| Seweryn Habdank-Wojewódzki \/\/

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[boost] building CVS HEAD on msvc 8.0
by Andy Stevenson 16 Jun '07

16 Jun '07

Hi, Moved from cygwin onto native msvc. Trying to build libraries from the HEAD sources on msvc and it can't find wtypes.h... windows.h etc I tried pointing at the mingw headers but that was a complete waste of time.... What am i doing wrong? Andy

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[asio] some design questions
by Yuval Ronen 16 Jun '07

16 Jun '07

Hi. I'm looking at the Design page of the asio docs (http://tinyurl.com/2b5afn) and several questions come to mind: 1. The "Proactor" page has Advantages/Disadvantages section, but it doesn't specify in comparison to what (advantages and disadvantages are always compared to something). I'm getting the impression that it's compared to the Reactor approach. Is this correct? 2. The "Platform-Specific Implementation" page notes that when using select/epoll/kqueue, demultiplexing is performed in one of the threads that calls boost::asio::io_service::run(). I assume that when this thread is awaken to perform some task, one of the other threads that called run() on the same boost::asio::io_service takes it position as waiting on select/epoll/kqueue. Is this correct? 3. The "Platform-Specific Implementation" page also notes that "An additional thread per io_service is used to emulate asynchronous host resolution. This thread is created on the first call to either boost::asio::ip::tcp::resolver::async_resolve() or boost::asio::ip::udp::resolver::async_resolve()." So I guess that if I resolve() rather than async_resolve(), then no thread is created, and the actual resolving is done in the thread that called resolve()? I think all these notes would be a good addition to the docs. Thanks.

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