Should an object write itself out to a file, or should another object act on it to perform I/O?

Question

NOTE: Sorry for the long question!

I\'m trying to understand some key areas behind object orientation and I couldn\'t decide one way or another about my par

Answer 1

I think the correct approach is the Case 1, but your class may be defined this way to take advantage of both approaches:

class Bob {

    IWriter _myWriter = null;

    public Bob(){
        // This instance could be injected or you may use a factory
        // Note the initialization logic is here and not in Save method
        _myWriter = new Writer("c://bob.xml")
    }

    //...
    public void Save(){

        _myWriter.Write(this);    

    }
    // Or...
    public void Save(string where){

        _myWriter.Write(this, where);

    }
    //...
}

This could be easily modified to put the writing logic and initialization in a base class so Bob class is even cleaner and independent of the persistence.