c++ BST and file handling - c++

Question

i am interested in creating a car register program:
menu for user to add, delete, find, edit(change a particular detail about the car) a car and view all the cars. this is then stored in memory using a binary search tree. all the cars are to be written out from memory into a csv file. also when loading the system it should read all the cars back in
car has 2 types petrol and electric.
every car has attributes car id, owner, make, model, numberplate
a petrol car has attributes miles, topup
an electric car has attributes power, miles
class car
{
string id
string owner
string make
string model
string numberplate
virtual getkey()//gets key being searched etc.
readfile();
writefile();
};
class petrol : public car
{
string miles
string topup
};
class electric : public car
{
string power
string miles
};
data structure:
class node
{
car *ptr
node *left
node *right
};
class tree
{
///insert delete etc.
};
would this be a practical class design and what functions might need to be included?

Answer 1

The problem with initial BST and Linked List implementations is that they either force you to use a specific data type or inherit from that data type (such as yours). If I want a BST for fruit, I can't use your tree, because your tree is dedicated to cars.
I suggest an abstract node class and deriving your data classes from the node class:
struct Node
{
boost::shared_ptr<Node> left;
boost::shared_ptr<Node> right;
// Interface functions for descendants
virtual bool is_less_than(boost::shared_ptr<Node> other_node) const = 0;
virtual bool is_equal_to(boost::shared_ptr<Node> other_node) const = 0;
};
I still believe the best design is to use a template:
template <class User_Data_Type>
class Node
{
public:
boost::shared_ptr<Node> left;
boost::shared_ptr<Node> right;
User_Data_Type m_data;
};