May 2009 - Boost-users - lists.preview.boost.org

[statechart] Several questions
by Michael Crawford 17 May '09

17 May '09

I'm evaluating Boost.Statechart for possible use in a turn-based strategy type game. It's very promising so far, I just would just like a little clarification on a few things. 1. Is there a clean way to seperate the definition of a state from the definition of its initial inner state? Say we have // StatePlayGame.h #include "MyStateMachine.h" class StateGameStartup; class StatePlayGame : public boost::statechart::state<StatePlayGame, MyStateMachine, StateGameStartup> { //... }; // StateGameStartup.h #include "StatePlayGame.h" class StateGameStartup : public boost::statechart::state<StateGameStartup, StatePlayGame> { //... }; It appears that any translation unit that includes StatePlayGame.h also requires StateGameStartup.h in order to compile - obviously a less than ideal situation. 2. Is it possible to pass parameters to a state's constructor? Going with the little example above let's say that StateGameStartup asks the player how many enemies he wants to fight, and then transitions to StateGameRunning, which needs that number. Can it be passed by StateGameRunning's ctor or is it just required that states can only share information via their context? Cheers, MC

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I can't build boost!
by Robert Dailey 17 May '09

17 May '09

What's going on? For some reason I can no longer build boost. I'm trying to build version 1.39 using bjam. The same command worked just fine on 1.38: D:\IT\personal\asl_editor\temp\boost_1_39_0>bjam --toolset=msvc --layout=system link=static threading=multi debug release stage

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Trouble reinstalling boost
by Simon Pickles 17 May '09

17 May '09

Hi, I had a nice build system set up on my VM ubuntu 8.10 server until I broke the VM. :) After rebuild the VM I am obviously reinstalling all the packages. Boost Python is causing me trouble. I built it from svn using bjam, boost 1_40_0. I can compile my python extension without error but when I run it the python code that uses it, I get: ImportError: libboost_python-gcc43-d-1_40.so.1.40.0: cannot open shared object file: No such file or directory I have this file on my system, and have copied it to /usr/local/lib simon@fenixurth:~/WorkingCopies/server/extended$ locate libboost_python-gcc43-d-1_40.so.1.40.0 /home/simon/source/boost/bin.v2/libs/python/build/gcc-4.3.2/debug/libboost_python-gcc43-d-1_40.so.1.40.0 /home/simon/source/boost/stage/lib/libboost_python-gcc43-d-1_40.so.1.40.0 /home/simon/WorkingCopies/server/extended/libboost_python-gcc43-d-1_40.so.1.40.0 /usr/local/lib/libboost_python-gcc43-d-1_40.so.1.40.0 Why is this not found? Thanks Simon

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[boost-users] istream_iterator question
by Max 17 May '09

17 May '09

Hello, I don't know why the following code does not work as expected. I hope the guru's here could lend me a hand. For a test data file: 3 1 2 3 4 5 6 2 1.2 4.3 234.2 3.5656 67.88 345.3 <eof> and 2 simple test helper class: struct a { int i, j; }; std::istream& operator>>(std::istream& in, a & p) { in >> p.i >> p.j; return in; } std::ostream& operator<<(std::ostream& out, const a & p) { out << p.i << " " << p.j; return out; } struct b { float i, j, k; }; std::istream& operator>>(std::istream& in, b & p) { in >> p.i >> p.j >> p.k; return in; } std::ostream& operator<<(std::ostream& out, const b & p) { out << p.i << " " << p.j << " " << p.k; return out; } Here is version 1, quite trivial and works just ok. std::ifstream is("./test.txt") int n; is >> n; std::cout << "n=" << n << "\n"; for(int i=0; i<n; i++) { a tmp; is >> tmp; va.push_back(tmp); } std::copy(va.begin(), va.end(), std::ostream_iterator<a>(std::cout, "\n")); is >> n; std::cout << "n=" << n << "\n"; for(int i=0; i<n; i++) { b tmp; is >> tmp; vb.push_back(tmp); } std::copy(vb.begin(), vb.end(), std::ostream_iterator<b>(std::cout, "\n")); The output is: n=3 1 2 3 4 5 6 n=2 1.2 4.3 234.2 3.5656 67.88 345.3 With version 2 using istream_iterator, the behavior is strange: is >> n; std::cout << "n=" << n << "\n"; std::copy_n(std::istream_iterator<a>(is), std::istream_iterator<a>(), n, std::back_inserter(va)); std::copy(va.begin(), va.end(), std::ostream_iterator<a>(std::cout, "\n")); is >> n; std::cout << "n=" << n << "\n"; std::copy_n(std::istream_iterator<b>(is), std::istream_iterator<b>(), n, std::back_inserter(vb)); std::copy(vb.begin(), vb.end(), std::ostream_iterator<b>(std::cout, "\n")); copy_n is defined as: template <class InputIterator, class Size, class OutputIterator> OutputIterator copy_n( InputIterator first, InputIterator last, Size n, OutputIterator result) { // copies the first `n' items from `first' to `result'. Returns // the value of `result' after inserting the `n' items. // it ends before n iterations, if the last iterator is reached while( n-- && first != last) { *result = *first; ++first; ++result; } return result; } The output is now: n=3 1 2 3 4 5 6 n=3 I've checked the code for several times and just not found the answer. I'm using VS2008SP1 on WinXP/SP1 Thanks for your help. B/Rgds Max

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doc on how to generate pdf doc
by Maurizio Vitale 17 May '09

17 May '09

anybody can point me to documentation on how to generate boost documentation in pdf format for printing and off-line reading? the library I'm interested in (proto) has documentation in quickbook format and I haven't found anywhere documentation on how to generate pdf. Eric has been very nice and provided pdf for many versions in the vault, but I'd like to learn to do it myself. Thanks a lot, Maurizio

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ASIO Tutorial 5 - Synchronising handlers in a multithreaded programs - Doesn't use both threads for processing
by mark 17 May '09

17 May '09

Using the code from http://www.boost.org/doc/libs/1_39_0/doc/html/boost_asio/tutorial/tuttimer5… with a few extra cout's for extra info. If you print out the thread IDs of at the start of print1 and print2 you'll see that both methods are actually using the same thread. ie two threads gets created but only one does any work. I'm printing the thread ID's via std::cout << "print1 " << boost::this_thread::get_id() << std::endl; std::cout << "print2 " << boost::this_thread::get_id() << std::endl; at the top of print 1 and print 2. I first noticed this when I was single line stepping through the code trying to work out how the second thread could possibly be doing anywork since t.join() is called after io.run(). Also if I comment out io.run() the program still works the same as before, except its the second thread doing all the processing. Compiler MSVC 9.0, happens on both debug and release.

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multi-array data ownership
by gtsml owevwr 16 May '09

16 May '09

Hi, I want to use multi-array but the original data is coming from, let say, a std::vector<float>. The data is quite big, do I need to copy it into a multi-array? Or maybe I can use a "view" as a proxy on top of the original data and therefore avoid a costly copy? Thanks, Frank

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[accumulators] density: empty values
by Robert Kubrick 16 May '09

16 May '09

I have the following program: #include <iostream> #include <boost/accumulators/accumulators.hpp> #include <boost/accumulators/statistics/stats.hpp> #include <boost/accumulators/statistics/density.hpp> using namespace boost; using namespace boost::accumulators; int main() { typedef iterator_range<std::vector<std::pair<double, double> >::iterator > histogram_type; accumulator_set<double, features<tag::density> > acc(tag::density::num_bins = 20, tag::density::cache_size = 10); // push in some data ... acc(0.1); acc(1.2); acc(2.3); acc(3.4); acc(4.5); acc(5.4); acc(5.5); acc(5.5); acc(10); // Display the results ... histogram_type hist = density(acc); for( int i = 0; i < hist.size(); i++ ) std::cout << "Bin lower bound: " << hist[i].first << ", Value: " << hist[i].second << std::endl; return 0; } Bin values and indexes don't seem to be initialized: $ acc_dist Bin lower bound: 0, Value: 0 Bin lower bound: 0, Value: 0 Bin lower bound: 0, Value: 0 Bin lower bound: 0, Value: 0 Bin lower bound: 0, Value: 0 Bin lower bound: 0, Value: 0 ...

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Range checked variable or class
by Ryan McConnehey 16 May '09

16 May '09

Is there a boost library or utility that can create a variable with a maximum and minimum acceptable value? Ryan

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intrusive::slist, MPL, Sun CC
by Chris Hite 16 May '09

16 May '09

intrusive::slist work with Sun CC? I notice that it uses some MPL. Does MPL generally not work with Sun CC? CC: Sun C++ 5.9 SunOS_sparc Patch 124863-12 2009/04/21 CC -I/development/tango/current/misc/boost/boost_1_39_0/SunOS/include/boost-1_39 -c test.cxx -o test.o test.cxx: Christopher Hite RTS Realtime Systems Software GmbH, Rembrandtstrasse 13, D-60596 Frankfurt am Main T: +49.69.61009.0 / F: +49.69.61009.181 Sitz: Frankfurt am Main - HRB 84467 Amtsgericht Frankfurt am Main Geschäftsführer: Steffen Gemuenden, Igor Sluga www.rtsgroup.net This email and any attachments are for the exclusive and confidential use of the intended recipient. If you are not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, please do not read, distribute or take action in reliance upon this message. If you have received this in error, please notify me immediately by return email and promptly delete this message and its attachments from your computer system. ------------------------------------------------------- #include <boost/intrusive/slist.hpp> using namespace boost::intrusive; struct CalcEntry: public slist_base_hook<none,none,none> {}; void foo(){ typedef slist<CalcEntry,cache_last<true> > CalcList; CalcList _calcList; } ------------------------------------------------------- "/development/tango/current/misc/boost/boost_1_39_0/SunOS/include/boost-1_39/boost/intrusive/slist.hpp", line 121: Error: pointer is not a member of boost::intrusive::detail::generic_hook<boost::intrusive::get_slist_node_algo<void*>, boost::intrusive::default_tag, 1, 2>. "/development/tango/current/misc/boost/boost_1_39_0/SunOS/include/boost-1_39/boost/intrusive/slist.hpp", line 1943: Where: While specializing "boost::intrusive::slist_impl<boost::intrusive::slistopt<boost::intrusive::detail::generic_hook<boost::intrusive::get_slist_node_algo<void*>, boost::intrusive::default_tag, 1, 2>, unsigned, 1, 0, 1>>". "/development/tango/current/misc/boost/boost_1_39_0/SunOS/include/boost-1_39/boost/intrusive/slist.hpp", line 1943: Where: Specialized in boost::intrusive::slist<CalcEntry, boost::intrusive::cache_last<1>, boost::intrusive::none, boost::intrusive::none, boost::intrusive::none, boost::intrusive::none>. "test.cxx", line 9: Where: Specialized in non-template code. "/development/tango/current/misc/boost/boost_1_39_0/SunOS/include/boost-1_39/boost/intrusive/slist.hpp", line 122: Error: const_pointer is not a member of boost::intrusive::detail::generic_hook<boost::intrusive::get_slist_node_algo<void*>, boost::intrusive::default_tag, 1, 2>. "/development/tango/current/misc/boost/boost_1_39_0/SunOS/include/boost-1_39/boost/intrusive/slist.hpp", line 1943: Where: While specializing "boost::intrusive::slist_impl<boost::intrusive::slistopt<boost::intrusive::detail::generic_hook<boost::intrusive::get_slist_node_algo<void*>, boost::intrusive::default_tag, 1, 2>, unsigned, 1, 0, 1>>". "/development/tango/current/misc/boost/boost_1_39_0/SunOS/include/boost-1_39/boost/intrusive/slist.hpp", line 1943: Where: Specialized in boost::intrusive::slist<CalcEntry, boost::intrusive::cache_last<1>, boost::intrusive::none, boost::intrusive::none, boost::intrusive::none, boost::intrusive::none>. "test.cxx", line 9: Where: Specialized in non-template code. "/development/tango/current/misc/boost/boost_1_39_0/SunOS/include/boost-1_39/boost/intrusive/slist.hpp", line 123: Error: iterator_traits is not a member of std. "/development/tango/current/misc/boost/boost_1_39_0/SunOS/include/boost-1_39/boost/intrusive/slist.hpp", line 1943: Where: While specializing "boost::intrusive::slist_impl<boost::intrusive::slistopt<boost::intrusive::detail::generic_hook<boost::intrusive::get_slist_node_algo<void*>, boost::intrusive::default_tag, 1, 2>, unsigned, 1, 0, 1>>". "/development/tango/current/misc/boost/boost_1_39_0/SunOS/include/boost-1_39/boost/intrusive/slist.hpp", line 1943: Where: Specialized in boost::intrusive::slist<CalcEntry, boost::intrusive::cache_last<1>, boost::intrusive::none, boost::intrusive::none, boost::intrusive::none, boost::intrusive::none>. "test.cxx", line 9: Where: Specialized in non-template code. "/development/tango/current/misc/boost/boost_1_39_0/SunOS/include/boost-1_39/boost/intrusive/slist.hpp", line 123: Error: A declaration does not specify a tag or an identifier. ......

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