December 2007 - Boost-users - lists.preview.boost.org

[program_options] std::wstring ??
by Robert Bielik 12 Dec '07

12 Dec '07

I've tried using the std::wstring with program options, couldn't make it work, only with std::string. Any workarounds? TIA /R

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[review] Gentle reminder - Fast track formal review of Boost.Functional/Factory will begin December 17
by John Torjo 12 Dec '07

12 Dec '07

Hi all, This is a gentle reminder of the Boost.Functional/Factory review, about to start next Monday. Factories are callback mechanisms for constructors, so we provide two function objects, boost::value_factory and boost::factory, that encasulate object construction through direct application of the constructor or operator new, respectively. These templates make other facilities that operate on function objects (such as standard algorithms, Boost.Bind, Boost.Function, or Fusion functional adapters) applicable to constructors. Get it from here: http://www.boost-consulting.com/vault/index.php?action=downloadfile&filenam… Best, John -- http://John.Torjo.com -- C++ expert ... call me only if you want things done right

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Supporting Visual Studio 6 in boost
by Mathieu Malaterre 12 Dec '07

12 Dec '07

Hi there, This is not exactly a user question, but I was wondering if a couple of boost developers could comment on the support of VS6 in boost. How much time consuming is it ? Are there plan to actually drop it at some point ? Were there cases where you had to provide a duplicate implementation (partial specialization, template template parameter, SFINAE...) with slight modifications, therefore making the boost code more difficult to maintain ? How much did this compiler impact the design of boost API / internals ? Thanks for comments, -- Mathieu Ps: I know there are other buggy compilers out there that are also 'supported', feel free to also add comment for another difficult to support compiler.

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Boost::Timer problem
by Simon Pickles 12 Dec '07

12 Dec '07

Hello, Using gcc on ubuntu, can anyone tell my why this simple code: ///////////////////////////////////////////////// #include <iostream> using namespace std; #include "boost/timer.hpp" #include <time.h> int main() { clock_t t = clock(); boost::timer bt; cout << t << " : " << bt.elapsed() << endl; sleep(10); t = clock(); cout << t << " : " << bt.elapsed() << endl; sleep(10); t = clock(); cout << t << " : " << bt.elapsed() << endl; return 0; } //////////////////////////////////////////////////////////////// produces output like this: 0 : 0 0 : 0 0 : 0 Its not cout, since pausing the program shows the values to be 0 in the watch window. Many thanks Simon -- Linux Counter: User# 424693

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boost::serialization - prevent object creation when loading a pointer
by Darryl Lawson 12 Dec '07

12 Dec '07

Peter Dimov wrote: > You can add > > virtual void load( boost::archive::text_iarchive& ar, unsigned v ) > = 0; > virtual void save( boost::archive::text_oarchive& ar, unsigned v ) > = 0; > > to base and call them in A::serialize, but this obviously only works > for a > specific archive type. I specifically need to be able to support different archives, so this won't work - but I think something similar to what you have suggested will. Robert Ramey wrote: > How about the following: > > template<class Archive> > void save(Archive& ar, const unsigned int version) const { > ar << _m; > cout << "serialise A, _m = " << (unsigned long)_m << endl;} > > void save(Archive& ar, const unsigned int version) const { > base * t; > ar >> t; // deserialize to a temporary > // modify _m according to t > cout << "serialise A, _m = " << (unsigned long)_m << endl; > delete t; > > } Yeh something like this would do the trick. So actually, what I am thinking of is a kind of a mix of Robert's and Peter's suggestions (see code below). It is not the prettiest, but I think I should only have to do this for one class hierarchy in particular, so it isn't too bad. Thanks for your help. The serialization library is going to make my life a lot easier! Darryl Lawson #include <iostream> #include <fstream> #include <cassert> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/export.hpp> using namespace std; struct base { virtual ~base() {} template<class Archive> void serialize(Archive& ar, const unsigned int version) {} virtual void load(const base* rhs) {} }; struct derived : public base { derived() : base(), _value(0) {} template<class Archive> void serialize(Archive& ar, const unsigned int version) { boost::serialization::void_cast_register<derived, base>(); ar & _value; } virtual void load(const base* rhs) { const derived* t = dynamic_cast<const derived*>(rhs); assert(t); if (!t) return; _value = t->_value; } int _value; }; BOOST_CLASS_EXPORT(derived); struct A { A() { _m = new derived; cout << "construct A, _m = " << (unsigned long)_m << endl; } template<class Archive> void save(Archive & ar, const unsigned int version) const { ar << _m; cout << "save A, _m = " << (unsigned long)_m << endl; } template<class Archive> void load(Archive & ar, const unsigned int version) { base* t; ar >> t; _m->load(t); delete t; cout << "load A, _m = " << (unsigned long)_m << endl; } BOOST_SERIALIZATION_SPLIT_MEMBER(); private: base* _m; }; void save(const A& a, const char* filename) { std::ofstream ofs(filename); boost::archive::text_oarchive oa(ofs); oa << a; } void load(A& a, const char* filename) { std::ifstream ifs(filename); boost::archive::text_iarchive ia(ifs); ia >> a; } int main(int argc, char* argv[]) { A a; save(a, "archive.txt"); A new_a; load(new_a, "archive.txt"); return 0; }

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boost::serialization - prevent object creation when loading a pointer
by Darryl Lawson 12 Dec '07

12 Dec '07

I realise that what I am doing is no doubt an unconventional usage of boost::serialization, but I wonder if any one has done a similar thing before. I wish to serialize a derived class through a baseclass pointer, but on deserilize I do not want the object to be created (I do not want memory allocated) - as the object will have all ready been created. An example, hopefully showing what I mean, is given at the end. The program will output something like, construct A, _m = 155640808 serialise A, _m = 155640808 construct A, _m = 155649400 serialise A, _m = 155649808 But essentially I want the program to output something lke, construct A, _m = 155640808 serialise A, _m = 155640808 construct A, _m = 155649400 serialise A, _m = 155649400 i.e. the second lot of construct A/serialise A will have the same address for _m. The reason why I need this behaviour, is that only a sub-set of the derived class will be seriliazed, with the other parts of the class intialised differently depending on the session, and the initialisation of the class is always done _before_ deserialisation. Is there anyway to get this behaviour from the boost::serialization library? Many thanks, Darryl Example ------- #include <fstream> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/export.hpp> using namespace std; struct base { virtual ~base() {} template<class Archive> void serialize(Archive& ar, const unsigned int version) {} }; struct derived : public base { derived() : base(), _value(0) {} template<class Archive> void serialize(Archive& ar, const unsigned int version) { boost::serialization::void_cast_register<derived, base>(); ar & _value; } int _value; }; BOOST_CLASS_EXPORT(derived); struct A { A() { _m = new derived; cout << "construct A, _m = " << (unsigned long)_m << endl; } template<class Archive> void serialize(Archive& ar, const unsigned int version) { // On deserialize this will create a new object, but I do not want it to, // rather I would like it to deserialize into the all ready created // object. ar & _m; cout << "serialise A, _m = " << (unsigned long)_m << endl; } base* _m; }; void save(const A& a, const char* filename) { std::ofstream ofs(filename); boost::archive::text_oarchive oa(ofs); oa << a; } void load(A& a, const char* filename) { std::ifstream ifs(filename); boost::archive::text_iarchive ia(ifs); ia >> a; } int main(int argc, char* argv[]) { A a; save(a, "archive.txt"); A new_a; load(new_a, "archive.txt"); return 0; }

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statechart unit testing
by Sean Kelly 12 Dec '07

12 Dec '07

Hi All, I have statechart implementation that I have spread over multiple translation units - I would like to unit test the control logic by inserting mock transition actions. The library is explicitly designed not to be dynamic - Can anyone suggest a way I could accomplish this - Its also likely that I could reuse the statechart control logic with different implementations of transition actions so if it is possible to inject this dependency I can reuse the code. Thanks Sean

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[ptr_container] How do I partition a ptr_vector
by Michael Marcin 11 Dec '07

11 Dec '07

How do I partition a ptr_vector? Most of the other standard algorithms seems to be members but I cannot find partition. Thanks, Michael Marcin

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[logging] Re: Getting started problem (on behalf of Benjamin de Dardel)
by John Torjo 10 Dec '07

10 Dec '07

Hi Benjamin, From what you've explained in your mail, it seems that you're trying to use Boost.Logging from a DLL and an EXE as well. I need to know more details about your scenario. My suggestion: - defining the logs (BOOST_DEFINE_LOG) should happen in the DLL - declaring the logs (BOOST_DECLARE_LOG) should happen in both EXE and DLL - DO NOT define the logs in the EXEcutable as well Note that at this time if you do logging before initializing the logs, nothing will happen - I will fix this very soon. Note: there's some problem with your email address and I can't reply to you directly. Please fix it. Best, John -- http://John.Torjo.com -- C++ expert ... call me only if you want things done right

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zero_vector, is it broken?
by Neal Becker 10 Dec '07

10 Dec '07

Either I completely misunderstand something, or zero_vector is seriously broken: #include <boost/numeric/ublas/vector.hpp> #include <iostream> #include <iterator> #include <algorithm> using namespace std; namespace ublas = boost::numeric::ublas; int main() { ublas::zero_vector<double> zeros (10); copy (zeros.begin(), zeros.end(), ostream_iterator<double> (cout, " ")); } I expect this to print 10 '0'. Instead, it prints nothing.

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