On Thu, Nov 5, 2009 at 1:33 AM, B Hart <
bhartsb@gmail.com> wrote:
> I have sent a couple of questions to this list in the past week and haven't
> gotten a single response. Wondering if my messages are being bounced???
>
> ---------- Forwarded message ----------
> From: B Hart <
bhartsb@gmail.com>
> Date: Wed, Nov 4, 2009 at 3:42 PM
> Subject: Serializing of object with map and multimap. Questions.
> To:
Boost-users@lists.boost.org
>
>
> I've been having some problems storing and loading a class with a map and a
> multimap. The map contains values that are simple objects of another
> class. My questions are below. Here is also a link to the same question
> posted on stackoverflow.
> Thanks.
>
>
http://stackoverflow.com/questions/1676781/boost-serializing-of-object-containing-map-with-object-values-and-multimap-wit
>
> See below a main() and two very simple classes. Then per Boost serialization
> (and what is shown) my questions are:
>
> 1) Does class B need the normal overloaded stream insertion operators '<<'
> and '>>' to be defined? Currently in my real code it doesn't have these.
>
> 2) Does class A in the store() and load() methods need to iterate through
> the map and multimap containers explicitly, storing/loading their key:value
> pairs explicitely? e.g. something like:
>
> void A::store(const char* filename){
>
>
>
> std::ofstream ofs(filename);
> boost::archive::text_oarchive oa(ofs);
>
>
>
> std::map< std::string, B >::iterator it;
>
>
> BMap.size();
> oa << BMap.size();
>
> for( it = BMap.begin(); it != BMap.end(); it++ ){
>
>
> oa << it->first;
> oa << it->second;
>
>
> }
>
> //similar for strMultimap
> }
>
> I assume that I don't need to do this, but am not certain.
>
> 3) Assuming class B has only the two data members shown, does it need a
> default contructor included explicitely? (as opposed to the implicit default
> constructor)
>
> 4) Does B need to have an overide for the comparison operator '>'? I assume
> that it doesn't since this is a very simple class.
>
> Finally, any other comments per anything that I've failed to cover is
> appreciated!
>
> Example code for my above questions:
>
> //includes ommitted
>
> int main() {
>
>
> std::string file("test.dat");
>
>
> A * pA = new A;
>
>
> pA->store(file.c_str());
>
> pA->fillMaps();
> //release data
> pA->load(file.c_str());
>
>
>
> return 0;
> }
>
> //includes ommitted
>
>
> class A
> {
> friend class boost::serialization::access;
>
>
>
> public:
>
> std::map< std::string, B > BMap;
>
>
> std::multimap< std::string, std::string > strMultimap;
>
>
>
> template<class Archive>
> void serialize(Archive & ar, const unsigned int version)
>
>
> {
> ar & BMap;
> ar & strMultimap;
>
> }
>
> void store(const char* filename){
>
>
> std::ofstream ofs(filename);
> boost::archive::text_oarchive oa(ofs);
>
>
> oa << this;
> }
>
> void load(const char* filename){
>
>
>
> std::ifstream ifs(filename);
> boost::archive::text_iarchive ia(ifs);
>
>
> ia >> this;
>
> }
>
> void fillMaps(){
>
>
> //code to allocate B objects and put them in BMap and fill strMultimap with
> whatever number of key:value pairs
>
> }
>
>
> class B
> {
> friend class boost::serialization::access;
>
>
>
> public:
>
> std::string str;
>
> unsigned int num;
>
> B::B(void)
>
> : str("a string")
> , num(7)
>
> {
> }
>
> template<class Archive>
>
> void serialize(Archive & ar, const unsigned int version)
>
>
> {
> ar & str;
> ar & num;
>
> }
> }