May 2012 - Boost-users - lists.preview.boost.org

Is boost::asio::ip::tcp::iostream thread safe?
by boost 10 May '12

10 May '12

hi all, I use ip::tcp::iostream but I don't know if it is thread safe, and I cannot find the answer in boost document. I read from ip::tcp::iostream in the receiver thread, and send request in another thread. Now I protected the stream with a mutex. But the problem is that, if I do not send request, the server will not response, and the receiver will block on read with lock, and the sender cannot hold the lock and cannot send the request, deadlock. Is there anyone know that? Please kindly give me an answer. Best Regards Zhanwei Wang

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[Boost users] [ublas] Type conversion warning with ublas::bounded_vector
by Matija Kecman 10 May '12

10 May '12

Hi Boost users! Is there a way for boost.ublas to warn of type conversions with ublas::bounded_vector's? I'm using this library for scientific computations and I came across this problem, I have quite a large code so I would be useful to know if this mistake occurs elsewhere. Here is a code example: int main() { double d = M_PI; unsigned u = d; cout << "d = " << d << endl; cout << "u = " << u << endl; bounded_vector<double,3> dVec = ublas::scalar_vector<double>(3,M_PI); bounded_vector<unsigned,3> uVec = dVec; // ATTENTION: type conversion! cout << "dVec = " << dVec << endl; cout << "uVec = " << uVec << endl; return 0; } When I compile this using g++ 4.6.1: g++ -g3 -Wall -Wextra -ansi -pedantic -Wconversion -std=c++0x test.cpp -o test I get the following warnings: test.cpp: In function ‘int main()’: test.cpp:11:22: warning: conversion to ‘unsigned int’ from ‘double’ may alter its value [-Wconversion] Program output: $ ./test d = 3.14159 u = 3 dVec = [3](3.14159,3.14159,3.14159) uVec = [3](3,3,3) The compiler produced a warning for the conversion of the scalars but there was no warning for the ublas conversion, is there a way of having the compiler write a warning in that case? -Wconversion or any of the other options don't do this. Best, Matija

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[Boost users] [Program_options] Is Boost.Program_options available as a header?
by Matija Kecman 10 May '12

10 May '12

Hi Boost users, I'm quite new to boost. I have written a program using the Boost Program Options library. In order to compile it I have to link with the boost program options library. I would like to run my program on a computer which only has access to boost headers. I was wondering if the program options library is available as a header only? If not, it would be interesting to know the reason for that :) Best, Matija

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time variant uuid
by Victor Whiskey Yankee 10 May '12

10 May '12

Hello List, How can I create uuids so that the first one compares less than the next one.. something like this: boost::uuids::t1 = boost::uuids::random_generator()(); boost::uuids::t2 = boost::uuids::random_generator()(); BOOST_REQUIRE (t1 < t2); I don't see how to replace random_generator() with a time-based variant, if that even makes sense. If this can be done, then is there a way to extract the date+time from it? Thanks, Vic

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[Pool] Why is pool allocator slower than ordinary allocator?
by Mr.C64 10 May '12

10 May '12

Please see this thread on StackOverflow: http://tinyurl.com/chh4yxj Thanks.

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[Statechart] Pass variable parameter to Player ctor?
by Dick Bridges 10 May '12

10 May '12

In the PingPong example, I'm trying to pass a std::string variable to the Player ctor through the fifo_schedular<>create_processor<>() in main(). No joy. Error: no matching signature. I'm missing something obvious. I've stared at that first override in the boost header and tried everything I could think of. Dead give away that I don't understand: I'm "trying" things. %>[ I'd sure appreciate it if someone could point me in the right direction. Are there async examples that pass variables through create_processor() to the ctorS? Thanks for taking the time to read this, Dick

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[build] How can I change how the linker is called?
by Daryle Walker 10 May '12

10 May '12

This is for my PowerPC Tiger Mac system. I've installed GCC 4.7 fromMacPorts on it. I have it set in C++11 mode. Yesterday, I wrote on the list that I couldn't get the example file torun in my new trial project. (It's at<https://github.com/CTMacUser/Unionize>.) As soon as I added acompile-fail test and the corresponding line to Jamfile, everything worked! Sort of. The compile-fail test fails as expected (at compile-time).The example file still doesn't run due to a linking error I've seen before: //========================================[daryle@daryle-walkers-emac:test]$ b2 toolset=gcc-4.7...found 30 targets......updating 14 targets...common.mkdir bincommon.mkdir bin/super_union_basics.testcommon.mkdir bin/super_union_basics.test/gcc-4.7common.mkdir bin/super_union_basics.test/gcc-4.7/debuggcc.compile.c++ bin/super_union_basics.test/gcc-4.7/debug/super_union_basics.ogcc.link bin/super_union_basics.test/gcc-4.7/debug/super_union_basicsld: unknown option: --start-groupcollect2: error: ld returned 1 exit status "g++-mp-4.7" -o "bin/super_union_basics.test/gcc-4.7/debug/super_union_basics" -Wl,--start-group "bin/super_union_basics.test/gcc-4.7/debug/super_union_basics.o" -Wl,-Bstatic -Wl,-Bdynamic -Wl,--end-group -g ...failed gcc.link bin/super_union_basics.test/gcc-4.7/debug/super_union_basics......skipped <pbin/super_union_basics.test/gcc-4.7/debug>super_union_basics.run for lack of <pbin/super_union_basics.test/gcc-4.7/debug>super_union_basics...common.mkdir bin/super_union_fail_test.testcommon.mkdir bin/super_union_fail_test.test/gcc-4.7common.mkdir bin/super_union_fail_test.test/gcc-4.7/debuggcc.compile.c++ bin/super_union_fail_test.test/gcc-4.7/debug/super_union_fail_test.oIn file included from super_union_fail_test.cpp:9:0://======================================== Now "ld" points to a version of ld64 from MacPorts, but that error hasshown up before this. I don't think my versions of "ld" have"--start-group" or "--end-group" options. What should they be instead,and where do I make these changes? (Even if no one here can answer thefirst part, they should be able to answer the second. That's where I'llmake the changes if I have to ask about the first part elsewhere.) Oh, I've uploaded the version of the project used here. Its SHA ID is"535241c3f13a9488bd845549ce3b1cf661ffcbac". (It's the latest as of this writing.) Daryle W.

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filesystem V3 path::normalize deprecated
by Shai Shasag 09 May '12

09 May '12

I have a question regarding the deprecated function path::normalize(). Before moving to V3 I used this function to resolve paths containing "..". For example: path myPath("/Dir_A/Dir_B/a.txt/.."); myPath->normalize(); now myPath is: "/Dir_A/Dir_B" How can this be done using V3 code? Thanks, Shai PS: Could not find in docs why this function was deprecated and what replacement available.

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c++ serial com connection
by Evaggelos Tsampazis 09 May '12

09 May '12

Hi! I would like to ask if I can use the boost libraries on the IDE environment of GodeGear RAD studio (C++ builder) 2009? I included the header file <boost/asio.hpp> but I got some compilation errors. I would like to use the boost libraries to make a connection to the mobile phone (via USB) to send and receive AT Commands to it. The asio part is the best boost solution for my case. Can anyone help to explain how to make boost libraries work in the environment I am working in? Thanks, Evaggelos

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[MSM] What's the easiest way to share data between states in a Boost.MSM state machine?
by B. Tommy Jensen 08 May '12

08 May '12

As the subject indicates, I'm trying to find the best way to share data between states in a MSM state machine. My first attempt has been to let each sub-machine and state inherit from a common base class, e.g.: struct MyStateMachine_ : public msm::front::state_machine_def<MyStateMachine_,CommonBaseClass> My idea is to add a reference to some shared data in the base class, making it easy to access the shared data from any state. The shared data reference must be passed to the base class. Questions: 1. Is it possible to pass constructor parameters to the common base class' constructor? I have tried different options without success, it seems that the default constructor with no arguments is the only option. 2. If 1. is not possible, what is the best way to initialize the shared property correctly? For example an easy method to iterate over all defined states? (not only the active ones). I have tried to iterate over all states with get_state_by_id, but this method does not enter sub-machines' states. 3. In general, what is the preferred way of implementing shared data between state classes in Boost.MSM? It would have been natural to store the data in the root state, but I can't see that there is an easy way to get access to the root FSM. (only the "nearest parent" FSM in the hierarchy is passed to the various event handler methods). Regards, Tommy

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