Class Templates question

Hi,

I am trying to use a template for my classes, eg:

Code:

---

template<class VEHICLE>
class SportsCar
{
//data members/functions
}

---

I am eventually aiming to hold all the objects within a single linked list.

My question though is that my classes whilst having the same member functions, they also have different data members.

Is this a problem? The tutorials I have read show the use of Templates, but the data members are always the same, unlike mine.

Perhaps I should declare all the different data members used by the separate inherited classes within the base class?

Any advice is appreciated.

Thanks! :)

Perhaps you should describe what is the problem that you are trying to solve before jumping into the use of templates.

Code:

---

class Vehicle
{

};

class Car : public Vehicle
{
int MPG;
int NoOfDoors;
}

class Motorbike : public : Vehicle
{
        int MPG;
};

---

In the code above , the base class is Vehicle.

The two inherited classes have different data members.

I want to use a Template (in the hope of storing the different objects within a single linked list).

Such as:

Code:

---

template<class VEHICLE>
class Vehicle
{

};

template<class VEHICLE>
class Car : public Vehicle
{
int MPG;
int NoOfDoors;
}

template<class VEHICLE>
class Motorbike : public : Vehicle
{
        int MPG;
};

---

I'm not saying I yet have a problem, I am wondering if having different data members in different classes stops you using a Template for all of the classes.

Quote:

---

Originally Posted by Swerve

I want to use a Template (in the hope of storing the different objects within a single linked list).

---

Your motivation to turn your classes into template classes seems strange: it sounds like you want to use a std::list<Vehicle*>, std::list<std::tr1::shared_ptr<Vehicle> > or boost::ptr_list<Vehicle> instead of involving templates.

Quote:

---

Originally Posted by Swerve

I'm not saying I yet have a problem, I am wondering if having different data members in different classes stops you using a Template for all of the classes.

---

No, it does not.

Thanks laserlight

That would be std::list<std::tr1::shared_ptr<Vehicle> >

Quote:

---

Originally Posted by CornedBee

That would be std::list<std::tr1::shared_ptr<Vehicle> >

---

Yes, and corrected accordingly.

Thanks very much :)

Code:

---

std::list<std::tr1::shared_ptr<Vehicle> >

---

I read this to mean there should be a shared pointer for the entire Vehicle type, and this pointer will point to all the objects within the list, yes?

Quote:

---

Originally Posted by Swerve

Thanks very much :)

Code:

---

std::list<std::tr1::shared_ptr<Vehicle> >

---

I read this to mean there should be a shared pointer for the entire Vehicle type, and this pointer will point to all the objects within the list, yes?

---

Not as such. shared_ptr is a "smart pointer" type that handles garbage-collection-type things for you (i.e., if all the shared_ptr's pointing to an object go out of scope, the object is deleted). But each pointer points to one object, and you have a list full of them.

You don't need anything that fancy to do the basic sort of thing you're trying to do, if you don't want it. A plain old Vehicle* can hold a pointer to all its derived types, without any nonsense about templates or the like.