August 2008 - Boost-users - lists.preview.boost.org

Re: [Boost-users] size_type doubts / integer library..
by Lang Stefan 19 Aug '08

19 Aug '08

-----Ursprüngliche Nachricht----- On Mon, Aug 18, 2008 at 12:06:08PM +0200, Lang Stefan wrote: > > > A) you intend to use your ID to later reference some address or offset > > (which is the same) in memory. If that is your intention, then you > > should stick to the size type (i. e. std:size_t). Problem solved. > > > Yes, it is used as an index into a vector. And that's what I did (typedef vector<..>::size_type pin_id). Well, then why don't you simply use std::size_t ? Yes, it's unsigned, and I agree with you it's not perfect (see below). But it will immediately rid you of all those nasty conversion warnings! > Hm, do they? Correct me if I'm wrong, but I don't think that C++ mandates flat address space -- it just > requires that each individual object has a contiguous memory representation. And there can be discrepancy > between the two, e.g. 80286 protected mode: largest segment size is 64k, yet the largest amount of > addressable memory is 16MB (or even in the range of TB if one allocates all LDTs and plays with swapping). Bugger, you're right, didn't think of that. > So, size_type should be able to represent the size of a *single* largest representable object. Why use it > for e.g. number of elements in a vector? That is something I did give some thought about in the past, to the point where I considered implementing my own set of container classes! However, I realized that in a sense, 'size_type' is indeed the correct type for an index. The reason behind it is this: an index type needs to be able to address a range of values that spans the minimum (0) and maximum (?) possible index for a container of some arbitrary type. For the STL, the smallest entity you can put inside a container is a single byte (disregarding bit-arrays). And the maximum number of such entities a container could legally contain would be limited by the amount of memory available divided by the size of the contained elements. While, as you pointed out, there doesn't need to be a direct relation from index to memory address, the range an index type needs to cover is equal to the range a 'size_type' needs to cover. Moreover, at least on a small scope, every architecture I am aware of groups values of container elements into one or more chunks of memory, which in turn store adjacent values into adjacent memory slots. So at least on a local scale, index values do correspond to memory addresses or memory offsets. > The "problem" could be solved by using largest _signed_ type both for size_type and difference_type. [snip] > So I'd advocate signed representation for size_type and difference_type. I agree. Stefan

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program_options does not compile
by dejfson 19 Aug '08

19 Aug '08

Dear All, if I try this piece of code: ---------------------------------------------- --------------------------------------------- extern "C" { #include <vmeapi.h> } #include <iostream> #include <signal.h> #include <string> #include <boost/program_options.hpp> // FANCY THINGY HERE: IF YOU INCLUDE CURSES BEFORE STRING, IT WILL BREAK COMPILATION #include <curses.h> //using namespace std; //namespace po = boost::program_options; static void sig_catch(int sig) { VME_Release(); /* Exception handler */ switch(sig) { case SIGINT : case SIGTERM : // nl(); // echo(); cout << "\nVME safe exit." << endl; VME_Release(); if (VME_IsErr()) { cout << "Errors at VME_Release():" << endl; VME_DispErr(); } exit(0); break; default : break; } } int main (int argc, char **argv) { /* Init VME access */ VME_Init(); if (VME_IsErr()) { VME_DispErr(); cout << "^C to quit." << endl;; } /* Turn off auto error reporting */ VME_ErrQuiet(); /* Install signal handler */ if (signal(SIGINT, &sig_catch) == (void *) -1) cout << "VMET Can't install SIGINT handler." << endl; if (signal(SIGTERM, &sig_catch) == (void *) -1) cout << "VMET Can't install SIGTERM handler." << endl; cout << "works somehow" << endl; VME_Release(); if (VME_IsErr()) VME_DispErr(); } ---------------------------------------------------------- ---------------------------------------------------------- it does not compile. Compilator identifies the problem as: g++ -pipe -fcommon -I/acc/local/ppc4/include -D__NO_INCLUDE_WARN__ -I/user/biswop/include -I./include -c main.cpp -o main.ppc4.o In file included from /acc/local/ppc4/include/boost/program_options.hpp:15, from main.cpp:8: /acc/local/ppc4/include/boost/program_options/parsers.hpp:156: parse error before `>' make: *** [main.ppc4.o] Error 1 ------------------------------------------------------------ By looking on the code in parsers.hpp I do not see any particular breaks, thus I suspect that there is something very odd with compiler. This piece of code is used on PPC processors in VME industrial crates. The operating system is LynxOS, however it uses quite old version of compiler - 2.95.3. I do not have any chance how to upgrade it as we use this compiler everywhere. Boost version is 1.33.1 (and again no chance to upgrade, however in this respect I could very probably force cross-compiler to compile the library) I would appreciate any info/hint how to make it running by using this compiler. Thanks a lot d.

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How to transform a single-threaded program into a multi-threaded program? (Source example)
by Stephen Torri 18 Aug '08

18 Aug '08

What I am trying to learn how to do is convert a single threaded program into a multi-threaded program. The task of the program is to analyze a text file a set number of times. Each analysis of the text file does not depend on another. The only thing that they need is the name of the file, how many iterations of the analysis to do and a unique id. I am not concerned about the information from each round being printed in sequential order. That is for example if thread A has a unique ID of 50 and thread B has a unique ID of 51 that I want thread B's output ahead of thread A's output. The output is going to be captured into a file and post-processed in a spreadsheet application. Below is a running example of what I am trying to do. To restate my question: How do I use boost threads to make a multi-threaded version of this program? Stephen ----- EXAMPLE CODE ----- #include <boost/bind.hpp> #include <boost/cstdint.hpp> #include <boost/format.hpp> #include <boost/program_options.hpp> #include <boost/shared_ptr.hpp> #include <boost/thread/thread.hpp> #include <iostream> #include <string> #include <sstream> class Work { public: std::string process ( boost::uint32_t round_number, boost::uint32_t iterations, std::string file ) { // Read file for data std::stringstream result; for ( boost::uint32_t index = 0; index != iterations; ++index ) { // Perform algorithm and save best result result << boost::format ("%1%:%2%") % round_number % index << std::endl; } return result.str(); } }; int main (int argc, char** argv) { boost::program_options::options_description generic ( "Generic options" ); generic.add_options() ( "help", "produce help message" ) ( "file", boost::program_options::value<std::string>(), "Target file" ) ( "rounds", boost::program_options::value<boost::uint32_t>(), "Number of rounds (default: 1)" ) ( "iterations", boost::program_options::value<boost::uint32_t>(), "Number of iterations (default: 5)" ); boost::program_options::variables_map vm; boost::program_options::store ( boost::program_options::command_line_parser ( argc, argv ). options(generic).run(), vm ); boost::program_options::notify ( vm ); if ( vm.count ( "help" ) ) { std::cout << generic << std::endl; return 0; } // Get values from command flags boost::uint32_t m_rounds = 1; boost::uint32_t m_iterations = 5; if ( vm.count ( "rounds" ) ) { m_rounds = vm["rounds"].as<boost::uint32_t>(); if ( m_rounds == 0 ) { std::cout << " Invalid number of rounds: 0" << std::endl; return 0; } } if ( vm.count ( "iterations" ) ) { m_iterations = vm["iterations"].as<boost::uint32_t>(); if ( m_iterations == 0 ) { std::cout << " Invalid number of iterations: 0" << std::endl; return 0; } } std::cout << "Number of rounds: " << m_rounds << std::endl; std::cout << "Number of iterations: " << m_iterations << std::endl; boost::shared_ptr<Work> data_alg_ptr ( new Work() ); for ( boost::uint32_t index = 0; index < m_rounds; ++index ) { std::cout << data_alg_ptr->process ( index, m_iterations, "data.txt" ) << std::endl; } return 0; }

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Re: [Boost-users] [swap] How to override swap now?
by Joseph Gauterin 18 Aug '08

18 Aug '08

Hi Terry, >How should a user/developer like me implement a custom swap so that users >get the benefit of my::swap, then boost::swap, and finally std::swap without >putting too much burden on my user. In the same way that swap functions are currently provided: either a specilization of std::swap or a 'swap' function in the same namespace as a UDT. >If the user does this... >using namespace std; >using namespace boost; >using namespace my; >And then somewhere in his code... > HisType a = MakeA(); > HisType b = MakeB(); > swap(a, b); // Unqualified? Or should the user specify a namespace? > Which one? A call to std::swap will swap the two values using temporary values and assignments. A call to boost::swap will call my::swap using argument dependent lookup. A call to my::swap will just call my::swap. An unqualified call to swap will call my::swap using argument dependent lookup. >If the user has his own swap(HisType, HisType) invoke that. >Otherwise, if HisType.swap() exists, then use that. >Otherwise, use my::swap() if its "better" than boost::swap >Otherwise, use boost::swap(), if its "better" than std::swap >Otherwise, just use std::swap(). boost::swap calls my::swap() if it exists, else it calls std::swap(). HisType.swap is not considered directly. >Sorry about all the ambiguity. But that's the real problem, isn't it? Indeed - but we're using a trick to make sure that boost::swap is never ambiguous with std::swap. So: using namespace std; using namespace boost; swap(a, b); Will call a function called swap in the namespace where 'a' is declared if it exists (adl), or std::swap otherwise. It will never call boost::swap. std::swap(a, b); Will swap 'a' and 'b' using temporaries and assignments. boost::swap(a, b); Will call a function called swap in the namespace where 'a' is declared if it exists, or std::swap otherwise. No 'using' statements or declarations are required. Joe.

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[Function] Comparing function objects with std::find
by Christian Larsen 18 Aug '08

18 Aug '08

Hi, I'm storing function objects in a std::vector, but to remove one again, I need to find an iterator to the one I want to remove. I do this in an "unregister" function taking a single boost::function<void ()> as parameter. Inside the function I would like to use the std::find algorithm to get an iterator to that function in the vector. I'm getting compile errors, though; see the example below. How do I fix these? I'm using MSVC++ 8 (SP1), and Boost 1.33.1 (can not upgrade). Example, where in my "unregister" function I use find as in the last part of this example (i.e. I have a Listener and not a plain function pointer). This does not compile: #include <algorithm> #include <vector> #include <boost/function.hpp> using namespace std; using namespace boost; void listenerA() {} void listenerB() {} int main() { typedef function<void ()> Listener; typedef vector<Listener> ListenerVector; ListenerVector listeners; listeners.push_back(&listenerA); listeners.push_back(&listenerB); ListenerVector::iterator iter; // This compiles and works iter = find( listeners.begin(), listeners.end(), &listenerB); assert(iter != listeners.end()); // This gives: // error C2666: 'boost::operator ==' : 4 overloads have // similar conversions iter = find( listeners.begin(), listeners.end(), Listener(&listenerB)); assert(iter != listeners.end()); return 0; } Compiler errors: c:\program files (x86)\microsoft visual studio 8\vc\include\algorithm(40) : error C2666: 'boost::operator ==' : 4 overloads have similar conversions d:\development\boost_1_33_1\boost\function\function_template.hpp(583): could be 'void boost::operator ==<R,Allocator>(const boost::function0<R,Allocator> &,const boost::function0<R,Allocator> &)' [found using argument-dependent lookup] with [ R=void, Allocator=std::allocator<void> ] d:\development\boost_1_33_1\boost\function\function_base.hpp(609): or 'bool boost::operator ==<boost::function<Signature>>(Functor,const boost::function_base &)' [found using argument-dependent lookup] with [ Signature=void (void), Functor=boost::function<void (void)> ] d:\development\boost_1_33_1\boost\function\function_base.hpp(600): or 'bool boost::operator ==<_Ty>(const boost::function_base &,Functor)' [found using argument-dependent lookup] with [ _Ty=boost::function<void (void)>, Functor=boost::function<void (void)> ] or 'built-in C++ operator==(void (__thiscall boost::function0<R,Allocator>::dummy::* )(void), void (__thiscall boost::function0<R,Allocator>::dummy::* )(void))' with [ R=void, Allocator=std::allocator<void> ] while trying to match the argument list '(boost::function<Signature>, const boost::function<Signature>)' with [ Signature=void (void) ] c:\program files (x86)\microsoft visual studio 8\vc\include\algorithm(74) : see reference to function template instantiation '_InIt std::_Find<std::_Vector_iterator<_Ty,_Alloc>,_Ty>(_InIt,_InIt,const _Ty &)' being compiled with [ _InIt=std::_Vector_iterator<Listener,std::allocator<Listener>>, _Ty=Listener, _Alloc=std::allocator<Listener> ] d:\development\misc\functionvector\functionvector.cpp(35) : see reference to function template instantiation '_InIt std::find<std::_Vector_iterator<_Ty,_Alloc>,boost::function<Signature>>(_InIt,_InIt,const _Ty &)' being compiled with [ _InIt=std::_Vector_iterator<Listener,std::allocator<Listener>>, _Ty=Listener, _Alloc=std::allocator<Listener>, Signature=void (void) ] Best regards, Christian

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Boost.Time_series library
by Kim Tang 18 Aug '08

18 Aug '08

Hi all, i ve downloaded the time_series.zip by the link: http://boost-consulting.com/vault/index.php?directory=Math%20-%20Numerics and unzip it on my computer. But the compilation of the example (time_series\time_series\main.cpp) program fails due to the errors: c:\boost\time_series\boost\sequence\size.hpp(27) : error C2143: syntax error : missing ';' before '<' 1> c:\boost\time_series\boost\sequence\size.hpp(33) : see reference to class template instantiation 'boost::sequence::impl::size<S,T>' being compiled 1>c:\boost\time_series\boost\sequence\size.hpp(27) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int 1>c:\boost\time_series\boost\sequence\size.hpp(27) : error C2238: unexpected token(s) preceding ';' 1>c:\boost\time_series\boost\sequence\size.hpp(29) : error C2143: syntax error : missing ';' before '(' 1>c:\boost\time_series\boost\sequence\size.hpp(29) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int 1>c:\boost\time_series\boost\sequence\size.hpp(30) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int After looking at the file boost\time_series\boost\sequence\size.hpp i see that the variable name range_size in line 27 is unknown. So my question is which file should i include? I ve searched for the variable name range_size in the time_series folder. And one possibility is the file boost\detail\range_concepts.hpp. But is this the right file? Thanks, Kim Tang

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shared_ptr custom deallocator - member function?
by Alejandro Martinez 18 Aug '08

18 Aug '08

can i use some class's (a kind of factory) member be used as a deallocator in a shared_ptr? like to do something like this: boost::shared_ptr<mysqlpp::Connection> cp(sDbPool->grab(), boost::bind(&mysqlpp::ConnectionPool::release, sDbPool)); where sDbPool is a shared_ptr to the "factory/pool manager". i tryed just that, but visual studio express 2008 keeps crashin on me. (the compiler crashes, not the program). any ideas?

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bjam only finding system python on mac
by David Philp 18 Aug '08

18 Aug '08

I am trying to write a python extension for the Python that comes with Sage (Sage bundles its own Python). My user-config.jam is supposed to direct bjam to the Sage version of Python, but whatever I do, it links to the System Python. I think my configuration is correct, because if I (as root) move the System Python.framework so that bjam cannot find it, I can compile a working extension. ("Working" in the sense that it can be loaded into Sage's python, and runs perfectly.) Otherwise (without hiding System Python), the extension compiles just fine, but cannot be loaded into the Sage version of python. When loaded into Sage's python, it fails with "Fatal Python error: Interpreter not initialized (version mismatch?)" which seems reasonable. The extension can be loaded into the System Python. Here are the details. I've used "Sage_root" for the base directory of Sage to make this a bit more readable. (It is actually /Users/dphilp/ sage-3.0.3.): boost 1.35.0 sage 3.0.3, which contains python 2.5.2p2 (slightly patched for sage, and is built using --enable-framework=Sage_root/local/Frameworks/Python.framework ) Everything seems to work fine, Sage's doctests run perfectly, etc. In user-config.jam (this is overkill, but I wanted to remove any possible ambiguity): using python : 2.5 : Sage_root/local/Frameworks/Python.framework/Versions/2.5/bin/python : Sage_root/local/Frameworks/Python.framework/Versions/2.5/include/ python2.5 : Sage_root/local/Frameworks/Python.framework/Versions/2.5/lib/ python2.5/config ; bjam --debug-configuration reports that it is using the requested version of python, i.e. the one inside Sage. Using --with-python=... on the command line does not help. When I use --debug-building, there is no hint of the System Python.framework anywhere. But when I run otool -L my_ext.so, it reports that the extension is linked to the System framework---that is, unless I hide the System framework, in which case it reports that it is linked to the Sage framework. This seems to me to be a bug in bjam, but I would appreciate any help either way. (Moving the System's python doesn't seem to be a good long term solution!) Thanks in advance for any answers or redirections. David ================================== David J Philp Postdoctoral Fellow National Centre for Epidemiology and Population Health Building 62, cnr Mills Rd & Eggleston Rd The Australian National University Canberra ACT 0200 Australia T: +61 2 6125 8260 F: +61 2 6125 0740 M: 0423 535 397 W: http://nceph.anu.edu.au/ CRICOS Provider #00120C

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STL iterator issue in signals::detail::named_slot_map_iterator on MS VisualStudio?
by Ákos Maróy 18 Aug '08

18 Aug '08

Hi, I'm trying to compile a code sample using boost signals on Windows using Visual Studio 2008, that works fine on Linux using gcc. My application crashes at the first time a signal's operator() method is called, and it seems that the issue is with some STL-related iterator magic. The application breaks in named_slot_map.hpp, in the call to boost::signals::detail::named_slot_map_iterator::init_next_group(), basically in operator== of class _Tree_nod, in file xtree - probably an MS STL implementation. basically it breaks here: #if _HAS_ITERATOR_DEBUGGING if (this->_Mycont == 0 || this->_Mycont != _Right._Mycont) { _DEBUG_ERROR("map/set iterators incompatible"); _SCL_SECURE_INVALID_ARGUMENT; } #else I tried to search on the issue, and found this thread: https://lists.secondlife.com/pipermail/sldev/2008-July/010867.html this even specifying _SECURE_SCL=0 doesn't help. I'm using boost 1.35.0, linking againts libboost_signals_vc90-mt-1_35. at the time of the call, actually there are no listeners bound to the signal. Is this an issue with boost::signals? or with MS VS? Akos

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XML Serialization forward compatibility
by Terdale, Shantibhushan 18 Aug '08

18 Aug '08

I am trying to use XML serialization for streaming data on network. I could understand that with versioning you can make any class backward compatible. I have a situation which demands the other way; I need to read and construct an old object from new XML data. Currently it throws stream_error exception for any newly added member. I am trying to figure out how to deal with it; either write new archive or derive from existing XML archive and do changes etc. I am wondering whether anybody has done any work towards this idea and would like to share their insight. Thanks Shanti

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