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

boost::format, print hex
by Lloyd 09 Jul '10

09 Jul '10

Hi, With the following program I am trying to print the hex of "a". But it is not printing it correctly. I have gone through the boost format sysntax specification. But I dont have any clue, what am I doing wrong? char a=0x11; stringstream ss; ss<<boost::format("%|02X|")%a; cout<<ss.str()<<endl; Thanks a lot, Lloyd ______________________________________ Scanned and protected by Email scanner

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Re: [Boost-users] asio, check remote socket open
by ecyrbe 09 Jul '10

09 Jul '10

>Hi, >I have a server application. It listens for connection and receives data. when data is received, the receive "handler routine" is called. Inside the handler there is async timer. This timer's handler again initiates a new >timer.This keeps on executing. During this time, the remote client which connects to the server closes the connection "intentionally". Inside the timer handler routine, is there any way to chek the connection is closed or >not? (From the timer handler, I can access the socket and io_service). >I have tried with >socket::is_open(), socket::remote_endpoint(), they are successfull and does not throw any exception. >Thanks a lot, > Lloyd As it was said, even reading is not reliable in case of a cable disconnection or even some strange ISP interruption. The only way is to try writing something to the user (a sort of application defined ping), beacause this should trigger a tcp error at one moment if the connection was closed. Needless to say, that the tcp client should do the same to detect properly closed connections. You can even add a timeout in both sides to monitor user or server activity (incoming and outgoing data), and close the connection if the timeout is reached....

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[bjam] boost compilation with cxxflags -fPIC
by alfC 09 Jul '10

09 Jul '10

Hi, Please, can anybody tell me how to compile Boost (e.g. 1.43) with the -fPIC as cxxflag: typicially I do ./bootstrap --prefix=$HOME/usr ./bjam ./bjam install There are some threads that give answers but in none of them it is clear exactly what is the command we need to write. I tried with CFLAGS=-fPIC ./bjam ./bjam cxxflags=-fPIC and still the result seems not to use -fPIC Thank you, Alfredo

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asio, check remote socket open
by Lloyd 09 Jul '10

09 Jul '10

Hi, I have a server application. It listens for connection and receives data. when data is received, the receive "handler routine" is called. Inside the handler there is async timer. This timer's handler again initiates a new timer.This keeps on executing. During this time, the remote client which connects to the server closes the connection "intentionally". Inside the timer handler routine, is there any way to chek the connection is closed or not? (From the timer handler, I can access the socket and io_service). I have tried with socket::is_open(), socket::remote_endpoint(), they are successfull and does not throw any exception. Thanks a lot, Lloyd ______________________________________ Scanned and protected by Email scanner

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[process] Child process hangs while capturing stdout
by Allen Cronce 08 Jul '10

08 Jul '10

Hi all, I'm not sure where to post this since boost.process is a candidate and not officially accepted to boost proper. If this should go elsewhere, please let me know. We're seeing hangs when running child command line executables under Mac OS X (posix) while capturing stdout. It seems to happen more often when the command line child app is verbose and spitting out a lot of output. To test this, I created a simple test app that outputs some number of random guids to cout. I then launched this child app from another test app using boost process, indicating that we're capturing stdout. If I run the test with just a few guids outputted (like 100), it works fine. But if I tell the test app to output 1000 guids, the child app hangs every time, attempting to flush the output stream: #0 0x96378249 in write$NOCANCEL$UNIX2003 () #1 0x963781ad in _swrite () #2 0x96376fdd in __sflush () #3 0x96376f79 in fflush () #4 0x91b1ecb2 in std::ostream::flush () #5 0x00005ae6 in main (argc=4, argv=0xbffff608) If I launch the child app manually with the same parameters (i.e. 1000 iterations), rather than programmatically via boost process, it works fine. The code I'm using to configure the environment of the test app is the following: --snip-- // context - Inherit our env and file descriptors bp::context ctx; ctx.environment = bp::self::get_environment(); ctx.stderr_behavior = bp::redirect_stream_to_stdout(); ctx.stdout_behavior = bp::capture_stream(); --snip-- But I've seen the same problem with other configurations, including when both stderr and stdout are being captured to their own streams, and when stdout is being inherited from the parent process. Looks like we're using boost.process 0.31, with some mods and fixes we implemented but have not yet given back (no changes to stdout or stderr capturing, though). We're building with Xcode 3.2.2 and gcc 4.0. We're running under Mac OS X 10.6.4. Any ideas as to what's wrong and how to fix or work around it? Best, -- Allen Cronce

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[program options] Is it possible to add new options during parsing?
by Jorge Moraleda 08 Jul '10

08 Jul '10

Hi, I am wondering if it is possible (and if so, what is the best way) to add new options to a parser during parsing, that is, during the call to run(). The use case scenario is that I have an option called 'type' and if the type specified at runtime equals 'string1' I want to allow and parse a set of extra options (which -of course- can only be specified after type), and if it equals 'string2' then I want to allow and parse a different set of extra options. To do this I am thinking of using a command_line_parser and invoking extra_parser() with a function that will invoke method options() on the command_line_parser object as appropriate. I am wondering if adding options during parsing is going to break something or if there is a cleaner way to achieve this. One of the reasons why I don't like this solution so much is the need to pass somehow the parser object to the funcion that does the extra parsing, although I think I can use bind for that. Thank you. Regards, Jorge

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heterogeneous tree container
by Hicham Mouline 08 Jul '10

08 Jul '10

Hello, I have need for a heterogeneous tree container that holds different types (all of them primitive, int, double...) except for the leaf nodes which would hold a POD. The depth of the tree is N, known at runtime, and constant through all the paths, the actual types of each node are only known at runtime as well. Each level holds the same type. The number of children at 1 level, is variable from 1 parent to the next. root (no data here) | | | type1 type1 type1 | | type2 type2 ... typeN typeN .... typeN There are no paths from root to leaf with a depth different from N. typeN is a struct containing only primitive types, known a compile-time, and instances of it are the result of calling a complex function with arguments of type1.... type_N-1. Note that I will generate the [1, N-1] part of the tree sequentially, but then call the complex function in parallel. I have looked at the ntree.hh but it seems to be a homogenous container. Any reusable container out there for this purpose, or is ntree reusable somehow? Regards,

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[conversion] Is there a boost lib for converting octet array to integral types?
by Mostafa 08 Jul '10

08 Jul '10

Hi all, Is there a boost utility for converting an array of octets to an integral type? Something along the lines of: boost::uint8_t const octetBuf[] = {0x23, 0x4e}; boost::uint32_t const thirtyTwoBit = some_function(octetBuf); Where some_function takes care of the padding based on endianness. Thanks, -Mostafa

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Serialization XML on windows and linux
by QUILLET Jean-Charles 08 Jul '10

08 Jul '10

Hi, I've been using the boost serialization for quite a few projects and it works realy well in many different situations. But today I'm facing a problem, I find very difficult to solve. I serialize objects in a XML archive for a project working on linux and windows using boost 1.38. And oddly my files are not compatible between the two plateforms. When I try to deserialize an object saved on a different plateform, the application crashes despite the fact that I catch possible exceptions. When I compare the two files, it seems that I have a difference of class_id Here is a sample of what I have on linux: <m_scene3D class_id="4" tracking_level="0" version="0"> <pNode class_id="6" class_name="Group" tracking_level="1" version="0" object_id="_1"> <Node class_id="5" tracking_level="1" version="0" object_id="_2"></Node> <noeuds class_id="7" tracking_level="0" version="0"> <count>0</count> <item_version>0</item_version> </noeuds> </pNode> ... </m_scene3D> And the same object on windows: <m_scene3D class_id="4" tracking_level="0" version="0"> <pNode class_id="6" class_name="Group" tracking_level="1" version="0" object_id="_1"> <Node class_id="7" tracking_level="1" version="0" object_id="_2"></Node> <noeuds class_id="8" tracking_level="0" version="0"> <count>0</count> <item_version>0</item_version> </noeuds> </pNode> ... </m_scene3D> In my file on windows, I don't have any object of a class_id="5", weird... Does any one know any reason for this behaviour ? Any idea greatly appreciated. Jean-Charles Quillet

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Fwd: [naive] relationship between deadline_timer and io_service
by Ernest Galbrun 08 Jul '10

08 Jul '10

Dear Boost community, I have a rather simple question (some would say dumb) : I have been using the deadline_timer in asio library for a couple of hours, but I don't get why it is associated with an io_service (in fact, I don't get why this is in this library rather than in the date_time or timer library). I know it may seem trivial, but it is not to me, and I am worried I am missing something. regards, Ernest Galbrun.

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