April 2007 - Boost-users - lists.boost.org

Re: [Boost-users] [serialization] Serialization through pointer to baseclass
by Pfligersdorffer, Christian 05 Apr '07

05 Apr '07

Hey Ruediger, you simply need to make toString() virtual :-) Life can be that simple sometimes... Best wishes, DI Christian Pfligersdorffer Software Engineering EOS GmbH > -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org]On Behalf Of Ruediger > Berlich > Sent: Wednesday, April 04, 2007 5:28 PM > To: boost-users(a)lists.boost.org > Subject: [Boost-users] [serialization] Serialization through > pointer to > baseclass > > > Hi there, > I am trying to serialize an object through a pointer to its > base class. > > My application is in the field of distributed processing. I have > a "communicator" type of class, which receives pointers from > other objects, > serializes them, sends the generated string over a network > for further, > remote processing and then deals with the responses. It is > supposed to know > nothing about the objects it serializes, except that they contain a > method "toString()", which is contained in the base class. > > However, when I call that method, I only get a serialization > of that base > class, not of the derived class. > > Here is some code to illustrate the problem. The output of > the program is > listed at the end of this posting. > > How can I achieve serialization of the derived class (without explicit > casting), if it is stored in a pointer to a base class ? > > My assumption is that this has to do with the fact that the > "serialization" > method cannot be virtual, as it is a member function template. > > Any help is appreciated. > > Thanks and have a good day, > Ruediger > > /************************************************************* > ************/ > // headers and namespace statements removed ... > > class base > :public vector<int> > { > friend class boost::serialization::access; > > template<class Archive> > void serialize(Archive & ar, const unsigned int version){ > using boost::serialization::make_nvp; > ar & make_nvp("vector", > > boost::serialization::base_object<std::vector<int> >(*this)); > } > > public: > base(){ /* nothing */ } > virtual ~base() { /* nothing */ } > > virtual void appendValue(int val) = 0; > > string toString(void){ > ostringstream ofs; > boost::archive::xml_oarchive oa(ofs); > // this should point to derived objects > oa << make_nvp("myp",*this); > return ofs.str(); > } > > void printType(void){ > cout << typeid(*this).name() << endl; > } > }; > > BOOST_IS_ABSTRACT(base); > > /************************************************************* > ***************/ > > class derived > :public base > { > friend class boost::serialization::access; > > template<class Archive> > void serialize(Archive & ar, const unsigned int version){ > using boost::serialization::make_nvp; > ar & make_nvp("base", > boost::serialization::base_object<base>(*this)); > } > > public: > derived(){ /* nothing */ } > virtual ~derived() { /* nothing */ } > > void appendValue(int val){ > this->push_back(val); > } > }; > > > BOOST_CLASS_EXPORT(derived); > > /************************************************************* > ***************/ > > main() > { > base *myp = new derived(); > myp->appendValue(1); > > // only serializes class "base" > cout << myp->toString(); > > cout << "===========================" << endl; > > myp->printType(); > // this in printType points to the correct type > cout << "===========================" << endl; > > // Explicit casting to the derived class yields the > correct response > derived *mypp = (derived *)myp; > ostringstream ofs; > boost::archive::xml_oarchive oa(ofs); > oa << make_nvp("myp",*mypp); > cout << ofs.str() << endl; > } > > /************************************************************* > ***************/ > > Here is the output of the program: > > <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> > <!DOCTYPE boost_serialization> > <boost_serialization signature="serialization::archive" version="3"> > <myp class_id="0" tracking_level="0" version="0"> > <vector> > <count>1</count> > <item>1</item> > </vector> > </myp> > =========================== > 7derived > =========================== > <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> > <!DOCTYPE boost_serialization> > <boost_serialization signature="serialization::archive" version="3"> > <myp class_id="0" tracking_level="1" version="0" object_id="_0"> > <base class_id="1" tracking_level="0" version="0"> > <vector> > <count>1</count> > <item>1</item> > </vector> > </base> > </myp> > > > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users >

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nested containers with boost?
by nicola 05 Apr '07

05 Apr '07

Hi, I would like an arbitrarily nested data structure, e.g. similar to std::vector< std::list<int> >, giving access to the elements of any of its subcontainers, but, at the same time, being a model of Container - in particular, having an iterator over all the elements in the last nesting level (int's in the previous example). Space/time efficiency is very important in my application. My solution would be to build a container adaptor similar to // vector of lists of ... of int typedef my_nested_container<std::vector, std::list, ..., int> nc_type; nc_type nc; (with type lists?) with an iterator adaptor that allows me to write something like: for (nc_type::iterator i = nc.begin(); i != nc.end(); ++i) // do smth with integer *i The nested container should also allow the user to modify each subcontainer and to iterate over the elements of a subcontainer, possibly without (much) overhead, e.g. // Iteration over the elements of one subcontainer for (nc_type::inner_iterator j = nc.inner_begin(); j != nc.inner_end(); ++j) // ... I have started to implement a prototype from scratch, but I am wondering whether I am reinventing the wheel. I think I can use boost::iterator_facade for my_nested_container::iterator and/or boost::pointer_container to build the nested structure internally (to minimize reallocation overhead upon dynamical change of the structure). Is there any other boost library I could take advantage from? I find that operations on a nested container are not completely trivial to implement (or even to define properly, think of add/remove in subcontainers which may themselves be nested containers) given its recursive nature, so I would be very glad to know that something like that is available off-the-shelf. I have found myself in need for such a data structure more often than not. Nicola

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[serialization] Serialization through pointer to base class
by Ruediger Berlich 05 Apr '07

05 Apr '07

Hi there, I am trying to serialize an object through a pointer to its base class. My application is in the field of distributed processing. I have a "communicator" type of class, which receives pointers from other objects, serializes them, sends the generated string over a network for further, remote processing and then deals with the responses. It is supposed to know nothing about the objects it serializes, except that they contain a method "toString()", which is contained in the base class. However, when I call that method, I only get a serialization of that base class, not of the derived class. Here is some code to illustrate the problem. The output of the program is listed at the end of this posting. How can I achieve serialization of the derived class (without explicit casting), if it is stored in a pointer to a base class ? My assumption is that this has to do with the fact that the "serialization" method cannot be virtual, as it is a member function template. Any help is appreciated. Thanks and have a good day, Ruediger /*************************************************************************/ // headers and namespace statements removed ... class base :public vector<int> { friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version){ using boost::serialization::make_nvp; ar & make_nvp("vector", boost::serialization::base_object<std::vector<int> >(*this)); } public: base(){ /* nothing */ } virtual ~base() { /* nothing */ } virtual void appendValue(int val) = 0; string toString(void){ ostringstream ofs; boost::archive::xml_oarchive oa(ofs); // this should point to derived objects oa << make_nvp("myp",*this); return ofs.str(); } void printType(void){ cout << typeid(*this).name() << endl; } }; BOOST_IS_ABSTRACT(base); /****************************************************************************/ class derived :public base { friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version){ using boost::serialization::make_nvp; ar & make_nvp("base", boost::serialization::base_object<base>(*this)); } public: derived(){ /* nothing */ } virtual ~derived() { /* nothing */ } void appendValue(int val){ this->push_back(val); } }; BOOST_CLASS_EXPORT(derived); /****************************************************************************/ main() { base *myp = new derived(); myp->appendValue(1); // only serializes class "base" cout << myp->toString(); cout << "===========================" << endl; myp->printType(); // this in printType points to the correct type cout << "===========================" << endl; // Explicit casting to the derived class yields the correct response derived *mypp = (derived *)myp; ostringstream ofs; boost::archive::xml_oarchive oa(ofs); oa << make_nvp("myp",*mypp); cout << ofs.str() << endl; } /****************************************************************************/ Here is the output of the program: <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="3"> <myp class_id="0" tracking_level="0" version="0"> <vector> <count>1</count> <item>1</item> </vector> </myp> =========================== 7derived =========================== <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="3"> <myp class_id="0" tracking_level="1" version="0" object_id="_0"> <base class_id="1" tracking_level="0" version="0"> <vector> <count>1</count> <item>1</item> </vector> </base> </myp>

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[serialization] bug? serializing a vector resets ignored element members
by n.torrey.pines＠gmail.com 04 Apr '07

04 Apr '07

Hi If I serialize a struct, while ignoring one of its members, the member retains its value. I understand that this is the inteded serialization semantics - what you ignore for reading and writing remains intact. However, if I do this with a vector, the ingored members of its elements get reset to their "default" values. I'm too lazy to pore over the sources, but I'm guessing this might be happening because the implementation of vector serialization calls its constructor (and assignment?) where a resize could probably be better. Here is the specific code I boiled down the manifestation of this feature/bug to: // creates writes "remove_me" file #include <iostream> #include <fstream> #include <vector> #include <boost/filesystem/fstream.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/vector.hpp> struct s { s() : i(0), j(0) {} s(int i, int j) : i(i), j(j) {} int i, j; private: friend class boost::serialization::access; template<typename Archive> void serialize(Archive& ar, const unsigned version) { // ignore j ar & i; } }; struct v { v(const s& x) : data(5, x) {} std::vector<s> data; void write(const char* name) const { std::ofstream out(name); boost::archive::text_oarchive ar(out); ar << *this; } void read(const char* name) { std::ifstream in(name); boost::archive::text_iarchive ar(in); ar >> *this; } private: friend class boost::serialization::access; template<typename Archive> void serialize(Archive& ar, const unsigned version) { ar & data; } }; int main() { using namespace std; const char name[] = "remove_me"; s si(1, 2); // j == 2 v vi(si); vi.write(name); vi.read(name); std::cout << vi.data[0].j << std::endl; // j == 0 }

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[mpl] insert not inserting?
by Scott Meyers 04 Apr '07

04 Apr '07

In my continuing effort to demonstrate my inability to get much of anything working with the MPL, I'm having trouble inserting a type into an existing set of types. The code compiles and runs, but the revised type sequence is empty. Here's the code: #include <boost/mpl/set.hpp> #include <boost/mpl/for_each.hpp> #include <typeinfo> #include <iostream> namespace mpl = boost::mpl; struct Base { virtual ~Base(){} }; struct A { virtual ~A(){} }; struct B { virtual ~B(){} }; struct Print { template<typename T> void operator()(const T&) { std::cout << typeid(T).name() << ", "; } }; int main() { typedef mpl::set<A, B> Constraints; // print contents of Constraints (should be the equivalent // of "[A, B,]") std::cout << '['; mpl::for_each<Constraints>(Print()); std::cout << "]\n"; // add Base to Constraints, call result BaseClasses typedef mpl::insert<Constraints, mpl::end<Constraints>, Base> BaseClasses; // print contents of BaseClasses (should be the equivalent // of "[A, B, Base, ]") std::cout << '['; mpl::for_each<BaseClasses>(Print()); std::cout << "]\n"; } Can anybody spot what I'm doing wrong? I know that I could use the two-argument form of insert with a set, but I'm trying to write code that will work with a vector, too, and at any rate, I get the same results with the two-argument form of set. Thanks, Scott

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[bind] binding a boost::reference_wrapper to a function template
by Barchenkov, Alexei (IT) 04 Apr '07

04 Apr '07

Rewording from a previous post: Are there any issues with binding a boost:ref to a free templated function? On gcc32 this generates an error: class Test { }; template <class T> void foo(T arg_) { } int main(int) { Test t; boost::reference_wrapper<Test> tr(t); boost::function<void()> fun1 = boost::bind(&::foo<boost::reference_wrapper<Test> >, tr); // line 41 } - Alex ________________________________ From: Barchenkov, Alexei (IT) Sent: Friday, March 23, 2007 12:55 PM To: boost-users(a)lists.boost.org Subject: question about binding a boost::reference_wrapper argument inside a templated function I am getting an error when compiling the following code on gcc32. Could someone please point out what is the problem? Thank you. class Test { }; template <class T> void foo(T arg_) { } template <class T> void fooRef(const T& arg_){ } int main(int) { Test t; boost::reference_wrapper<Test> tr(t); boost::function<void()> fun1 = boost::bind(&::foo<boost::reference_wrapper<Test> >, tr); // line 41 boost::function<void()> fun2 = boost::bind(&::fooRef<boost::reference_wrapper<Test> >, tr); // line 42 } .... /ms/dist/fsf/PROJ/boost/1.33.1/common/include/boost/bind.hpp: In member function `void boost::_bi::list1<A1>::operator()(boost::_bi::type<void>, F&, A&, int) [with F = void (*)(boost::reference_wrapper<Test>), A = boost::_bi::list0, A1 = boost::reference_wrapper<Test>]': /ms/dist/fsf/PROJ/boost/1.33.1/common/include/boost/bind/bind_template.h pp:20: instantiated from `boost::_bi::result_traits<R, F>::type boost::_bi::bind_t<R, F, L>::operator()() [with R = void, F = void (*)(boost::reference_wrapper<Test>), L = boost::_bi::list1<boost::reference_wrapper<Test> >]' /ms/dist/fsf/PROJ/boost/1.33.1/common/include/boost/function/function_te mplate.hpp:136: instantiated from `static void boost::detail::function::void_function_obj_invoker0<FunctionObj, R>::invoke(boost::detail::function::any_pointer) [with FunctionObj = boost::_bi::bind_t<void, void (*)(boost::reference_wrapper<Test>), boost::_bi::list1<boost::reference_wrapper<Test> > >, R = void]' /ms/dist/fsf/PROJ/boost/1.33.1/common/include/boost/function/function_te mplate.hpp:479: instantiated from `void boost::function0<R, Allocator>::assign_to(FunctionObj, boost::detail::function::function_obj_tag) [with FunctionObj = boost::_bi::bind_t<void, void (*)(boost::reference_wrapper<Test>), boost::_bi::list1<boost::reference_wrapper<Test> > >, R = void, Allocator = std::allocator<void>]' /ms/dist/fsf/PROJ/boost/1.33.1/common/include/boost/function/function_te mplate.hpp:430: instantiated from `void boost::function0<R, Allocator>::assign_to(Functor) [with Functor = boost::_bi::bind_t<void, void (*)(boost::reference_wrapper<Test>), boost::_bi::list1<boost::reference_wrapper<Test> > >, R = void, Allocator = std::allocator<void>]' /ms/dist/fsf/PROJ/boost/1.33.1/common/include/boost/function/function_te mplate.hpp:294: instantiated from `boost::function0<R, Allocator>::function0(Functor, boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functo r>::value>::value, int>::type) [with Functor = boost::_bi::bind_t<void, void (*)(boost::reference_wrapper<Test>), boost::_bi::list1<boost::reference_wrapper<Test> > >, R = void, Allocator = std::allocator<void>]' /ms/dist/fsf/PROJ/boost/1.33.1/common/include/boost/function/function_te mplate.hpp:638: instantiated from `boost::function<R ()(), Allocator>::function(Functor, boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functo r>::value>::value, int>::type) [with Functor = boost::_bi::bind_t<void, void (*)(boost::reference_wrapper<Test>), boost::_bi::list1<boost::reference_wrapper<Test> > >, R = void, Allocator = std::allocator<void>]' test10.C:41: instantiated from here /ms/dist/fsf/PROJ/boost/1.33.1/common/include/boost/bind.hpp:229: conversion from `Test' to non-scalar type `boost::reference_wrapper<Test>' requested /ms/dist/fsf/PROJ/boost/1.33.1/common/include/boost/bind.hpp: In member function `void boost::_bi::list1<A1>::operator()(boost::_bi::type<void>, F&, A&, int) [with F = void (*)(const boost::reference_wrapper<Test>&), A = boost::_bi::list0, A1 = boost::reference_wrapper<Test>]': /ms/dist/fsf/PROJ/boost/1.33.1/common/include/boost/bind/bind_template.h pp:20: instantiated from `boost::_bi::result_traits<R, F>::type boost::_bi::bind_t<R, F, L>::operator()() [with R = void, F = void (*)(const boost::reference_wrapper<Test>&), L = boost::_bi::list1<boost::reference_wrapper<Test> >]' /ms/dist/fsf/PROJ/boost/1.33.1/common/include/boost/function/function_te mplate.hpp:136: instantiated from `static void boost::detail::function::void_function_obj_invoker0<FunctionObj, R>::invoke(boost::detail::function::any_pointer) [with FunctionObj = boost::_bi::bind_t<void, void (*)(const boost::reference_wrapper<Test>&), boost::_bi::list1<boost::reference_wrapper<Test> > >, R = void]' /ms/dist/fsf/PROJ/boost/1.33.1/common/include/boost/function/function_te mplate.hpp:479: instantiated from `void boost::function0<R, Allocator>::assign_to(FunctionObj, boost::detail::function::function_obj_tag) [with FunctionObj = boost::_bi::bind_t<void, void (*)(const boost::reference_wrapper<Test>&), boost::_bi::list1<boost::reference_wrapper<Test> > >, R = void, Allocator = std::allocator<void>]' /ms/dist/fsf/PROJ/boost/1.33.1/common/include/boost/function/function_te mplate.hpp:430: instantiated from `void boost::function0<R, Allocator>::assign_to(Functor) [with Functor = boost::_bi::bind_t<void, void (*)(const boost::reference_wrapper<Test>&), boost::_bi::list1<boost::reference_wrapper<Test> > >, R = void, Allocator = std::allocator<void>]' /ms/dist/fsf/PROJ/boost/1.33.1/common/include/boost/function/function_te mplate.hpp:294: instantiated from `boost::function0<R, Allocator>::function0(Functor, boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functo r>::value>::value, int>::type) [with Functor = boost::_bi::bind_t<void, void (*)(const boost::reference_wrapper<Test>&), boost::_bi::list1<boost::reference_wrapper<Test> > >, R = void, Allocator = std::allocator<void>]' /ms/dist/fsf/PROJ/boost/1.33.1/common/include/boost/function/function_te mplate.hpp:638: instantiated from `boost::function<R ()(), Allocator>::function(Functor, boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functo r>::value>::value, int>::type) [with Functor = boost::_bi::bind_t<void, void (*)(const boost::reference_wrapper<Test>&), boost::_bi::list1<boost::reference_wrapper<Test> > >, R = void, Allocator = std::allocator<void>]' test10.C:42: instantiated from here /ms/dist/fsf/PROJ/boost/1.33.1/common/include/boost/bind.hpp:229: could not convert `(+a)->boost::_bi::list0::operator[](const boost::reference_wrapper<T>&) const [with T = Test](this)' to `const boost::reference_wrapper<Test>&' -------------------------------------------------------- NOTICE: If received in error, please destroy and notify sender. Sender does not intend to waive confidentiality or privilege. Use of this email is prohibited when received in error.

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Initialization and shutdown code with boost::unit_test_framework
by Jules d'Entremont 04 Apr '07

04 Apr '07

I have a set of unit tests that require an initialization function to be called once at program startup, and a shutdown function to be called at program exit. Something like this: int main() { init(); // run unit tests fini(); } Is it possible using the unit test framework for me to substitute my own main() function for the one that normally gets run by the framework? Or is there some other way of accomplishing the same thing? Jules d'Entremont.

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assign with my container
by abir basak 04 Apr '07

04 Apr '07

Hi, I am inheriting a vector for some reason. Just like template<typename T> class my_vector : public std::vector<T>{ }; I want my_vector to take the advantage of boost::assign library. How to do it? Thanks abir -- Abir Basak, Member IEEE Software Engineer, Read Ink Technologies B. Tech, IIT Kharagpur email: abir(a)abirbasak.com homepage: www.abirbasak.com

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[MultiIndex] typo in tutorial
by Christian Henning 04 Apr '07

04 Apr '07

Hi there, maybe it has been fixed already. In the section Sequenced Indices there is a type in the sample code. *(s.begin()) == 1; should be *(s.begin()) = 1; Christian

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how subslice can be made from some disjoint section ?
by abir basak 04 Apr '07

04 Apr '07

Hi, I have a ublas vector (or it can be std::vector also). Where I want to perform certain operation as a rotating basis. The program below illustrates it. std::vector<int> v; v+=1,2,3,4,5,6,7,8,9; ublas::vector<int> v1(v.size()); std::copy(v.begin(),v.end(),v1.begin()); std::cout<<ublas::sum(ublas::subrange(v1,1,3))<<std::endl; std::cout<<ublas::sum(ublas::subrange(v1,7,2))<<std::endl; In the first case I got a sum for [1 ,3) , I also want to get a sum for [7, 2) in a wrapped (circular )way. So is there any range functionality provides it in that way ? I also want some std algorithms to perform over some iterator adapter in a wrapped way .I can write such iterators , but are they already exist in boost ? Thanks abir basak -- Abir Basak, Member IEEE Software Engineer, Read Ink Technologies B. Tech, IIT Kharagpur email: abir(a)abirbasak.com homepage: www.abirbasak.com

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