Agustín K-ballo Bergé wrote:
Is it possible to append serialized elements to an existing archive?
the serialization library doesn't currently address this situation.
I need to keep a set of records on a file, and periodically add new entries to it (kind of like a database table). Reading the whole set, adding the new records, and serializing the set back is not an option since I expect the set to go pretty big.
I understand and sympathise.
I have tried to keep several archives at the same stream (with no_header and no_tracking flags),
I believe this might be made to work.
but then I don't know how to read them. Reading them as if they were a single archive does not work, should it?
no. Here's an idea. // append a bunch of archives to a file main(..){ ofstream os(..); // open for append { oarchive oa(os) oa << a bunch of stuff } // close archive leaving stream open { oarchive oa(os) oa << a bunch of other stuff } // close second archive } // now we have a closed stream with several self-contained archives in it // read a bunch of archives from one file main(..){ ifstream is(...); // open the normal way { iarchive ia(..); // open first archive ia >> first bunch of stuff } // close first archive leaving stream open { iarchive ia(..); // open first archive ia >> second bunch of stuff } // close second archive leaving stream open } // close input stream exercise for the reader. Figure out where to save the Number of archives inthe file. A couple of ideas 1) a separate companion file 2) save a few bytes at the beging of the file - call this archive count. Update this after every "append" and read it duning load. Good Luck with this. Robert Ramey main(..
Agustín K-ballo Bergé.-