如何转储我的类（带有 stl 容器），以便下次快速加载？

Question

I have a large container class to read file and save some data, it looks like:

class MyData {
 public:
  void Load(const std::vector<string>& file_paths) {  // this is a slow funuction, need to read a lot of files.
     for (const auto & f : file_paths) {
       // read file, and save the data in to stl containers
     }
  }
 private:
  std::vector<double> a;
  std::unordered_map<string, double>b; // there may be more containers.
}

everytime when i need to use this class, i need to:

MyData mdata;
std::vector<std::string> fs; // thousands of files need to read
mdata.Load(fs); // very slow

but the Mdata not update frequently, Can i dump it out, and use the dumped class, so make it faster? For example:

MyData load_dump(const std::string& dump_file_path) {
  // help needed
}

const MyData& mdata = load_dump("dump.bin"); // load the dumped file, to speed up

Can you help on this?

Answer 1

Sure you can. For vector<double> you can simply use ofstream::write(a.data(), a.size()) . For things like maps you need to do some kind of serialization because their internal representation is more complex. You could use http://www.boost.org/libs/serialization/ for a somewhat generic solution or you could write the code yourself.