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[fusion] Accessing sequence elements at runtime
by Christian Henning 28 Mar '07

28 Mar '07

Hi there, is it somehow possible to access a sequence element at runtime? Just image you're reading some name value pairs from file and you would like them to assign them to a fusion sequences. This way I don't know they order the values are supplied. Is that possible? For example take the following code: #include <string> #include <algorithm> #include <functional> #include <vector> #include <boost/any.hpp> #include <boost/bind.hpp> #include <boost/fusion/sequence.hpp> using namespace std; using namespace boost; struct A {}; struct B {}; struct info { string name; any value_type; }; static info info_table[] = { { "A_Value", any( A() ) }, { "B_Value", any( B() ) } }; string& get_name( info& i ) { return i.name; } typedef fusion::map< fusion::pair< A , int > , fusion::pair< B , double > > seq_type; int _tmain(int argc, _TCHAR* argv[]) { // Image a file read has delivered the following name value pair. string name = "A_Value"; int a_value = 12; // Find the type of the supplied name info* p = find_if( &info_table[0] , &info_table[0] + 2 , bind( equal_to<string>() , bind( &get_name, _1 ) , name )); seq_type seq; // How to add the value to the supplied name?? } Christian

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[boost::pool] problem with allocation
by Seweryn Habdank-Wojewódzki 28 Mar '07

28 Mar '07

Hi! Below if small code for testing of pool_allocator. The program below is working quite good. But if I change 10`000 to 100`000 or more then program never ending. Regards. #include <list> #include <iostream> #include <algorithm> #include <iterator> #include <boost/pool/pool_alloc.hpp> int main() { using namespace std; //print_list(std::cout,primes::PrimesLE(10000000)); list<int,boost::pool_allocator<int> > p; for ( int i = 0; i < 10000; ++i ) p.push_back(i); //copy ( p.begin(), p.end(), ostream_iterator<int>(cout,"\n") ); //boost::singleton_pool<boost::pool_allocator_tag, sizeof(int)>::release_memory(); } -- |\/\/| Seweryn Habdank-Wojewódzki \/\/

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[Statechart] Reusing states
by Philippe DAVID 27 Mar '07

27 Mar '07

Hi, I would like to reuse a state in statechart at different places of the state machine (so it can be a sub-state of at least 2 other states) or in different state machines. Since the state class has a template parameter with the context I am a bit stuck here. Have you done that yet or have an idea about how to do it ? Thanks, Philippe

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[boost::wave] MSVC 8 warning
by Ovanes Markarian 27 Mar '07

27 Mar '07

Hello, I would like to address this issue to boost::wave authors. First of all great lib! Many thanks! During the compilation with MSVC8 Express Edition I get a warning: c:\boost\include\boost-1_33_1\boost\wave\cpp_context.hpp(112) : warning C4355: 'this' : used in base member initializer list c:\boost\include\boost-1_33_1\boost\wave\cpp_context.hpp(106) : while compiling class template member function 'boost::wave::context<IteratorT,LexIteratorT>::context(const std::_String_iterator<_Elem,_Traits,_Alloc> &,const std::_String_iterator<_Elem,_Traits,_Alloc> &,const char *,const TraceT &)' with [ IteratorT=token_groups::str_iter_type, LexIteratorT=token_groups::lex_iter_type, _Elem=char, _Traits=std::char_traits<char>, _Alloc=std::allocator<char>, TraceT=boost::wave::context_policies::default_preprocessing_hooks ] My typedefs look like: typedef wave::cpplexer::lex_token<> token_type; typedef wave::cpplexer::lex_iterator<token_type> lex_iter_type; typedef std::string::iterator str_iter_type; typedef wave::context<str_iter_type, lex_iter_type> context_type; typedef context_type::iterator_type ctx_iter_type; Is there any chance that this warning will be suppressed in the next release, since it is a little bit annoying. I can't do anything about it as a user of wave and I also try to follow the rule to compile clean without warnings. Many thanks and With Kind Regards, Ovanes Markarian

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BOOST: Any planned release?
by dhruva 27 Mar '07

27 Mar '07

Hi, I am particularly looking for the boost::interprocess package. Is there any plan for a release in the near future? Has someone been using this in their production environment now. I have a real need and am evaluating if it is complete enough (with not too many changes planned) for me to replace the existing IPC mechanism used by us (McAfee). with best regards, dhruva -- Dhruva Krishnamurthy Contents reflect my personal views only!

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[serialization] custom xml archive and dynamic linking (VC 8.0)
by Sergey Skorniakov 27 Mar '07

27 Mar '07

Hello. I have tried to inherit my custom archive from xml_iarchive_impl and found no way to do it if macro BOOST_SERIALIZATION_DYN_LINK is defined. May be anybody already do that and can suggest me how?

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Re: [Boost-users] [test] detect_memory_leak option in msvc 8
by KLINIK Markus SDI2-G (AREVA NP GmbH) 27 Mar '07

27 Mar '07

> I am trying to get the --detect_memory_leak=1 option to detect a > memory leak in my code. Hi! In MSVC 7.0 the memory leak detection is somewhat primitive (I don't know about MSVC 8). I'm using Boost.Test together with mpatrol and it works great! Here is the output of a test run: <mpatrol_output> top 4 unfreed memory entries in leak table: bytes count location -------- ------ -------- 400 1 d:\[snip]\unittests\test_config.cpp line 10 84 1 d:\[snip]\tcpstream\src\myenv.cc line 145 24 1 c:\src\boost_1_33_1\libs\thread\src\mutex.inl line 55 8 1 c:\src\boost_1_33_1\libs\thread\src\tss_hooks.cpp line 29 516 4 total </mpatrol_output> NB. The first memory leak is intentional, the second is a resource leak from cppadvio. It also detects the already discussed resource leaks in Boost.Treads :) I needed some try-and-error to find the correct versions of mpatrol, Boost.Test and the windows runtime library, but now that it works, it is incredibly useful. (/MDd, mpatrolmt.dll, libboost_unit_test_framework-vc7-mt-gd.lib) Just for comparison, here is the output of the MSVC 7.0 memory leak detection of the same code: <msvc_output> Detected memory leaks! Dumping objects -> {11225} normal block at 0x00F3AA60, 24 bytes long. Data: < > 18 EE 14 00 FF FF FF FF 00 00 00 00 00 00 00 00 {11224} normal block at 0x00F3BBB0, 8 bytes long. Data: <` > 60 AA F3 00 01 CD CD CD {201} normal block at 0x00F35F90, 400 bytes long. Data: < > CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD {147} normal block at 0x00F35880, 84 bytes long. Data: < =b > 10 3D 62 00 00 00 00 00 00 00 00 00 FF FF FF FF Object dump complete. </msvc_output> Best regards Markus Klinik

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Proper initialization of a boost::shared_ptr<> in a constructor
by Stephen Torri 27 Mar '07

27 Mar '07

I am attempting to hunt down why I am getting a segmentation fault from the boost::shared_ptr class. I know that it has to do with how I am managing my shared pointers. That is creating and using them in functions. I am reading the best practices web page and I have a question about the best way to initialize a shared_ptr. Normally I have a class like the following: class A { public: typedef boost::shared_ptr<A> ptr_t; A ( int input_value ) : value ( input_value ) {} private: int value; }; Which I will use in another place: class A_User { public: A_User () : m_a_ptr ( new A() ) {} private: A::ptr_t m_a_ptr; }; Is this the correct way to initialize the A::ptr_t held in the A_User class in its constructor? Stephen

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[boost::function] problem with void type as argument type
by Seweryn Habdank-Wojewódzki 26 Mar '07

26 Mar '07

Hi! I have small piece of code and I do not know why it is not compiling - proper instantiation of function is not created. It means, why boost::function can not deduct types (code below). The problem is when type U is void. Can any one help me with it? Regards. template < typename T, typename U > void test ( boost::function<T(U)> & f ) { f(); } int f3() { std::cout << "f3(void)" << std::endl; return 3; } void f4() { std::cout << "f4(void)" << std::endl; return;// 4; } int main() { boost::function<int (void)> h = &f3; boost::function<void (void)> i = &f4; test (h); test (i); } -- |\/\/| Seweryn Habdank-Wojewódzki \/\/

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Re: [Boost-users] [bind] static array vs. pointer vector
by Daniel 26 Mar '07

26 Mar '07

> Date: Mon, 26 Mar 2007 11:24:08 -0400 > From: "Christian Henning" <chhenning(a)gmail.com> > Subject: [Boost-users] [bind] static array vs. pointer vector > To: boost-users(a)lists.boost.org > Message-ID: > <949801310703260824n31c76204pcd63bb686169e15c(a)mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Hi there, I have posted this question last Friday, already. But maybe > my example was too confusing. Here is a more simple example. > Basically, I don't see what the big difference is when using > boost::bind with a pointer vector ( std::vector<info*> ) and a static > array of info. > > Please consider the following code: > > #include <string> > #include <algorithm> > #include <functional> > #include <vector> > > #include <boost/bind.hpp> > > using namespace std; > using namespace boost; > > struct info > { > int a; > string s; > }; > > static info table[] = > { > { 16, "Hello" }, > { 18, "Moin" } > }; > > string& get_s( info* p ) > { > return p->s; > } > > int _tmain(int argc, _TCHAR* argv[]) > { > { > vector<info*> v; > find_if( v.begin(), v.end() > , bind( equal_to<string>() > , bind( &get_s, _1 ) > , "Moin" )); > } > > { > find_if( &table[0], &table[0] + 2 > , bind( equal_to<string>() > , bind( &get_s, _1 ) > , "Moin" )); > > } > } > > The second find_if wont complie using MSVC 7.1. The errors are: > > c:\boost\boost\bind.hpp(219) : error C2664: 'std::string &(info *)' : > cannot convert parameter 1 from 'info' to 'info *' [snip] > > Any ideas? > > Christian In 1st case, when you dereference vector<info*> iterator, you will get info* pointer. But in 2nd case, your iterator is info* pointer, so you get info object when you dereference it. This is also mentioned at beginning of error message - "cannot convert parameter 1 from 'info' to 'info *'". Therefore you should change your get_s() function to accept info (or info&), or your binding expression to convert info to info*. Daniel

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