August 2010 - Boost-users - lists.preview.boost.org

cstdint.hpp causes warnings on VC10
by Michael Kaes 24 Aug '10

24 Aug '10

HI all, after switching to VC10 I recognized that including the cstdint.hpp header causes a warning. After looking into this header I saw that all defines like INT8_C are guarded to prevent multiple defines, except of the UINT8_C define (cstdint.hpp Line:400). Is this done on purpose because to me it looks as if the guard was just forgotten. Regards, Michael

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[accumulators] chaining accumulator outputs
by Allen Chuang 24 Aug '10

24 Aug '10

Is there a way to chain the output of an accumulator and use it as the input of another accumulator? The sort of case I am thinking about is for example calculating the max of a rolling_mean. One obvious way to do this is to write a new rolling_mean_max accumulator and make it depend on rolling_mean, but the inner logic would be 99% duplicate of max. I was wondering if there was a way to do this without so much code duplication. -- GRATIS für alle GMX-Mitglieder: Die maxdome Movie-FLAT! Jetzt freischalten unter http://portal.gmx.net/de/go/maxdome01

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number cores / cpu
by Kraus Philipp 24 Aug '10

24 Aug '10

Hello, can I determine how many physical cpu and cores are installed in a system with the boost lib? Under *nix I would read /proc but I would like to do that with boost, because of "os-less". Thanks Phil

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boost::asio SSL connection thru proxy server
by Kumar, Akhilesh 24 Aug '10

24 Aug '10

Hi, I am writing a boost socket client using boost::asio to do secure HTTP (HTTPS) communication. I Implemented my client based on the code sample based on (http://www.boost.org/doc/libs/1_39_0/doc/html/boost_asio/example/ssl/client…) with little changes as I am using sync socket. My client woks fine, when I am connecting to server directly, but I am not sure what changes I need to make when my communication going thru proxy. The unsecure connection(HTTP) work fine thru proxy, and here is what I do for unsecure connection, 1. Initialize boost socket(IO service and other stuff). 2. Resolve and Connect to Proxy server. 3. Start writing to actual server(HTTP send request). 4. Start uploading/downloading. 5. Close Socket. But I can't use this above procedure for (SSL) secure connection as I need to do handshaking with the server before I can write anything if my understanding is correct. Can somebody give me some pointer or code sample or step I need to do when I am doing secure connection thru proxy server. Just to clarify Microsoft WinInet does do (secure) HTTPS connection thru same proxy fine. If providing my code sample I am using for SSL might help understand the problem I can provide that. Thanks in advance for any help. Akhilesh Kumar

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Using boost::bind with stl algorithms
by przemyslaw.sliwa＠uk.bnpparibas.com 24 Aug '10

24 Aug '10

Hello, I have the following question. I have two containers std::set<std::string> insertedEvents; std::vector<std::string> eventNames; How I would like to copy all those elements from eventNames which are not in insertedEvents. Can this can be done somehow using the boost::bind feature? I am doing it at the moment using a silly loop: for(size_t i=0; i<eventNames.size(); i++) { if (m_insertedEvents.find(eventNames[i])==m_insertedEvents.end()) eventNamesDegraded.push_back(eventNames[i]); } Thanks for any kind of help, Pshemek ___________________________________________________________ This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and delete this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is prohibited. Please refer to http://www.bnpparibas.co.uk/en/information/legal_information.asp?Code=ECAS-… for additional disclosures.

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bug in asio?
by Hei Chan 23 Aug '10

23 Aug '10

Hi, I am using a 3rd party library that uses boost::asio. The 3rd party library will call asyn_receive() with a callback handler, then when boost::asio::detail:: receive_op::do_complete() calls the callback handler, the handler consumes the message, calls asyn_receive() and then if there is no more message, it (the thread) waits for a condition -- the callback handler gets called again. The problem now is that once there is no more message, the thread enters the wait condition, and it never gets waken up again. Is it incorrect to enter the wait condition in the same thread that calls boost::asio::detail:: receive_op::do_complete()? Thanks in advance. Cheers, Hei

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Getting started with Boost.Test
by Otto 23 Aug '10

23 Aug '10

Hi, I'm very new to C++ and Boost. I want to make a simple desktop application (a game editor, basically read/write a binary file) using QtCreator. Right now I'm only interested in Boost.Test for the unit tests. I tried to install using the instructions in "Getting started" but wasn't able to, probably because of bad english and lack of C++ knowledge. I unpacked Boost to /home/otto/boost_1_44_0/ >From there, I ran: $ mkdir dist $ ./bootstrap.sh --prefix=/home/otto/boost_1_44_0/dist --show-libraries --with-libraries=test $ ./bjam install It seems that config had no effect as it built everything (instead of just test) and to bin.v2/. A few "cp: cannot create regular file `/usr/local/lib/libboost_wave.a': Permission denied" errors too. What went wrong? Now I have bin.v2/libs/test/build/gcc-4.4.4/release with directories link-static and threading-multi. I also would like to configure it for usage with QtCreator. Thanks

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Best method for making synchronous call from async handler
by David Daeschler 23 Aug '10

23 Aug '10

Good evening, Currently I have an application running on boost asio working very well. To simplify the heck out of it, it takes requests via tcp and passes back binary information stored on disk. However, I now need to add an extra step to processing. If the data is not available on the local disk, the server needs to contact one or more peer servers it knows about, send a query to each one via UDP asking if it has the data, and then use an existing TCP connection to that server to retrieve the asset. This step must be completed before any more processing can be done for the current client even though the client may be sending even more requests while we process. My question is, what is the best method for me to achieve the goal? Should I set up another io_service for the UDP query step along with retrieving the data from the other server? Is there a good wait to wait on that io_service to complete? Also in the case that one of the servers has gone away, can I use a deadline timer to cancel the UDP recvfrom if I don't get a response in time from one or more servers? I should also probably keep this second io_service alive throughout the lifetime of the application? Thank you in advance for advice on tackling this problem the right way with asio. -- David Daeschler

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mpl::fold problems
by sergey kostanbaev 23 Aug '10

23 Aug '10

Hello everybody! I'm a newbie in boost and I've got some problems with boost::mpl #include <boost/mpl/vector.hpp> #include <boost/mpl/fold.hpp> #include <boost/mpl/arithmetic.hpp> template <class T, unsigned space=1> struct tr_field2 { static const unsigned count = space; } typedef boost::mpl::vector4< tr_field2<int, 4>, tr_field2<int, 7>, tr_field2<char, 1>, tr_field2<char, 1> > Test_description; I want to calculate a sum of all tr_field2::count I've read in the docs mpl::fold is for the case. I tried to compose typedef boost::mpl::fold<Test_description, boost::mpl::int_<0>, boost::mpl::plus<boost::mpl::_, boost::mpl::_::count > > >::type fcount; but it won't compile. It seems I misundestood something.

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[BGL] Change order of edge iterator
by John Robertson 23 Aug '10

23 Aug '10

I want to be able to iterate through the edges in any given order, not just the order specified by tie(edge_iter, edges_end) = edges(g);. Is it possible to do something like the following. typename graph_traits<Graph>::edge_iterator edge_iter1, edges_end1, edge_iter2, edges_end2, edge_iter3, edges_end3; tie(edge_iter1, edges_end1) = edges(g); sort(edge_iter1, edges_end1, ordering_1()); tie(edge_iter2, edges_end2) = edges(g); sort(edge_iter2, edges_end2, ordering_2()); tie(edge_iter3, edges_end3) = edges(g); sort(edge_iter3, edges_end3, ordering_3()); (ordering_x() specified by some struct) Then I would have 3 different orderings of the edges available. Would this work or should I use an iterator adapter, or create a map and (if its possible) obtain an iterator from the mapping, or something else. Thanks

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