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Meta State Machine, wayward transition
by Archie Campbell 28 Aug '13

28 Aug '13

Hello, I have a simple state machine, that uses only standard rows and no internal transitions, to which I am sending events that are clearly in the transition table for the state that the machine is in, yet the no_transition handler is running for this particular event. I have not yet been able to discover any reasons for a compiling transition table to fail to process an event that is listed in the row against the source state. Have I missed something fundamental? Regards, Archie

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Interprocess : multithreading of the mapping
by Oodini 27 Aug '13

27 Aug '13

Hello, I have several shared memory regions to map in my client process. May I experience troubles if use multithreading to do this operation ? (http://www.boost.org/doc/libs/1_54_0/doc/html/interprocess/sharedmemorybetw…) I have a good reason to do that. Thanks !

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Interoperability of multiple boost versions.
by Wilfried Kirschenmann 26 Aug '13

26 Aug '13

Hi all, I'm currently working on a large software project having an unchangeable dependency on boost 1.33, but I would like to use functionality from a more up-to-date version of the library (say 1.54). Can it be done? If so, how ? One of the things we aim to achieve is use the std::hash and unoredered_map from boost 1.54, while also using othe containers from boost 1.33. Since boost if mostly header only and template-based, using an intermediary interface doesn't work well. Any ideas ? Are we better off using another library instead of boost to avoid conflicts ? Help appreciated, thanks. Kind regards, Wilfried K. ----- Cordialement, Wilfried Kirschenmann "Ma femme, si elle croit que je vis, croit que je marche. Les camarades croient que je marche. Ils ont tous confiance en moi. Et je suis un salaud si je ne marche pas."* *Guillaumet (1902 - 1940) cité dans *Terre des Hommes* par Antoine de Saint-Exupéry (1900 - 1944)

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[geometry] problems with the ring concept
by Lepere Renaud 25 Aug '13

25 Aug '13

I have an existing geometric structure, and i try to make it usable with boost geometry. I read the documentation for a similar problem but i did not successhttp://www.boost.org/doc/libs/1_54_0/libs/geometry/doc/html/geometry… My Ring structure is very simple : typedef std::vector< Point > Points; struct Ring { Points points; }; void f() { boost::geometry::concept::check< Geom::Ring >(); } show failure since apparently my range does not support a clear() method correctly. however i think i implemented correctly the range adaption namespace boost/geometry/traints template<> struct tag< Geom::Ring > { typedef ring_tag type; }; namespace Geom inline Geom::Points::iterator range_begin(Ring & ring) { return ring.points.begin(); } inline Geom::Points::iterator range_end(Ring & ring) { return ring.points.end(); } inline Geom::Points::const_iterator range_begin(const Ring & ring) { return ring.points.begin(); } inline Geom::Points::const_iterator range_end(const Ring & ring) { return ring.points.end(); } and in namespace boost template <> struct range_mutable_iterator< Geom::Ring > { typedef Geom::Points::iterator type; }; // i tried also with range_iterator template<> struct range_const_iterator< Geom::Ring > { typedef Geom::Points::const_iterator type; }; I am a bit lost. Did i missed something obvious ? Thanks, Renaud

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[logging] operator<< not called if logger initialized by init_from_settings()
by Eric Prud'hommeaux 25 Aug '13

25 Aug '13

Following the standard recipe for a severity logger, I failed to get a logger configured by parsing a settings file to property invoke the operator<< for the severity. I tested by creating two logs, one by parsing and one by explicit construction (attached). Below, the former (starting with "parse: ") does not call the operator<< while the latter (staring with (const: ") does: [[ parse: : <> normal 1 severity_enum.cpp:25: operator<<(0x164dce0, 0) const: : <normal> normal 1 parse: : <> criticial 2 severity_enum.cpp:25: operator<<(0x164dce0, 1) const: : <critical> criticial 2 ]] It also doesn't matter whether the explicitly constructed logger is before the parsed logger: [[ severity_enum.cpp:25: operator<<(0x20b5d40, 0) const: : <normal> normal 1 parse: : <> normal 1 severity_enum.cpp:25: operator<<(0x20b5d40, 1) const: : <critical> criticial 2 parse: : <> criticial 2 ]] I've also tested this with a severity_channel logger with the same result. typedef unsigned int severity_level; (and some #defines) shows that the specialized operator<<(..., severity_level) isn't called at all, but at least the std:: one prints integers: [[ parse: : <0> normal 1 const: : <0> normal 1 parse: : <1> criticial 2 const: : <1> criticial 2 ]] I haven't worked out how to construct a settings object directly (as opposed to using the setting parser). I guess that's the next test. -- -ericP

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Installing (in the b2 sense) boost under windows
by Chris Stankevitz 24 Aug '13

24 Aug '13

Hello, I was recently tasked with installing boost binaries under windows. I used this command: C:\boost_1_49_0>b2 --build-dir=\boost-build toolset=gcc --build-type=complete stage --prefix=c:\boost-prefix\ install I was expecting the directory c:\boost-prefix to contain boost header and library files; however, that directory contained no files whatsoever. Did I do something wrong? PS: The c:\boost-build directory was filled with intermediate build files. Thank you, Chris

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[asio] Infinite loops
by Michael Chisholm 24 Aug '13

24 Aug '13

I have found that when (ab)using asio in a particular way, it causes a hang in my app, which I think is caused by an infinite loop in asio. I'll state up front that the usage is pretty underhanded, so I may not get much sympathy here :) But it also seems reasonable to not hang. The hang happens only on the two linux platforms I tested, which were centos 5.9 and 6.4. I built it on win7 and mingw 4.6.3 (with slight code changes), and it doesn't hang. The simplified test app demonstrating the hang is pasted at the bottom of this email. I basically just wanted an API to smooth over platform network API differences and also give me a nice iostream class backed by a socket. So there's none of the fancy proactor stuff. There is a need to "reset" the app after socket connections have been established, and one thread is blocked on a socket read. So I needed a way to unblock the thread. Closing the socket seemed like a reasonable way to do it, but I found that simply calling a close() method from a different thread doesn't work; it causes race conditions and crashes, since asio classes seem not to be thread-safe. So I got more devious, and decided to just grab the raw handle and call close() directly on it. That's the underhanded part. I thought asio would figure out that the socket's no longer valid, and propagate an error up to the caller, thus unblocking the thread. But it doesn't, the thread just stays blocked. After doing some gdb tracing, it looked to me like asio is repeatedly polling the socket with epoll/select (I tried the latter by defining BOOST_ASIO_DISABLE_EPOLL) and a timeout, and never breaking out of its loop even though the socket is no longer valid. So, does it seem reasonable for asio to break out of its polling loop when someone (underhandedly) closes the socket out from under it? :) Andy #include <cstdio> #include <boost/system/error_code.hpp> #include <boost/chrono.hpp> #include <boost/thread.hpp> #include <boost/asio.hpp> using namespace std; namespace bs = boost::system; namespace bc = boost::chrono; namespace ip = boost::asio::ip; boost::asio::io_service iosvc; ip::tcp::socket clientSocket(iosvc); ip::tcp::iostream serverStream; #define TEST_PORT 2000 void connectToServer() { bs::error_code ec; clientSocket.connect( ip::tcp::endpoint(ip::address_v4::loopback(), TEST_PORT), ec); if (ec) cout << "Client couldn't connect: " << ec.message() << endl; else cout << "Client connected!" << endl; } void waitForClient() { ip::tcp::acceptor acceptor(iosvc, ip::tcp::endpoint(ip::address_v4::loopback(), TEST_PORT)); bs::error_code ec; acceptor.accept(*serverStream.rdbuf(), ec); if (ec) cout << "Server couldn't accept: " << ec.message() << endl; else cout << "Server accepted!" << endl; } void serverReadAByte() { int b = serverStream.get(); if (serverStream) cout << "Got byte: " << b << endl; else cout << "Error reading byte: " << serverStream.error().message() << endl; } int main(int, const char **) { boost::thread serverThread(waitForClient); // wait a second for the server socket to open... boost::this_thread::sleep_for(bc::seconds(1)); connectToServer(); serverThread.join(); int sd = serverStream.rdbuf()->native_handle(); // this will block, since we won't write anything // to the client socket. boost::thread readThread(serverReadAByte); // wait a second for the socket read to block... boost::this_thread::sleep_for(bc::seconds(1)); // close the server socket out from under our stream! // Does readThread unblock? if (close(sd) == -1) { perror("close"); return 1; } cout << "Waiting for read thread..." << endl; readThread.join(); clientSocket.close(); serverStream.close(); return 0; }

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[multiprecision] mpfi_sqr function
by Александров Петр 24 Aug '13

24 Aug '13

Hello. Is mpfi_sqr (square) function supported by Boost.Multiprecision? This function may give better results (interval with less length) than simple multiplication. Kind regards, Petr.

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Do I need a seperate boost_python lib for python 3?
by Neal Becker 24 Aug '13

24 Aug '13

If I already built against python2.7, do I need to build again against python 3? This is on Fedora 19 linux.

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Re: [Boost-users] boost::any_range with an abstract class reference
by Sergey Zhuravlov 24 Aug '13

24 Aug '13

Hi, you wrote: > typedef boost::any_range< Try use reference to value as value_type template parameter for boost::any_range. Also you can use boost::indirected_range instead.

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