Re: Saving and reloading a container to/from disk

On Mar 31, 7:07 am, jacob navia <ja...@jacob.remcomp.fr> wrote:


Here's a solution, what constitutes "best" depends on what you
consider important:

If the container contains Plain-Old-Data types or pointers to PODs --
first fread()/fwrite() the size() [if its variable]. After that just
iterate over the elements, and fread() / fwrite() the data,
dereferencing as appropriate as you go. If you've got pointers to
polymorphic types, make sure their base type has a [virtual]
serialize(), and each derived types implementation includes enough
extra header information the first element to determine its type

// Could easily be a static member function...
Base* unserialize()
{
  FILE* file_descriptor = fopen("filename","rb");
  // read header, determine DerivedType
  switch(DerivedType){
  case DerivedType1:
    return DerivedType1::unserialize(file_descriptor);
  case DerivedType2:
    return DerivedType2::unserialize(file_descriptor);
  /// etc
  default:
    throw(std::runtime_error("Unrecognised derived type header in
Base* unserialize()"));
 }
}

Dumping the vtable / function pointers, even if you can find them, is
a recipe for disaster.