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.

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.

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> >

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?

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.