C++ Creating Child Class from a Parent Class that's already been initialised

Question

I have a class "Player". Its members are simple strings and ints and I've got Getters and Setters for each of these...basic stuff: (there's a load of members so I've just given 3 to shrink the code):

PLAYER.H

class Player
{
private:
string Name;
string Role;
    int FFDefence;
    ......etc

public:
//constructor function
Player(
string Name = "Not Stated",
string vRole = "Not Stated",
    int vFFDefence = 0,
    ......etc
    )


//Getter Functions
string GetName() const;
string GetRole() const;
    int GetFFDefence() const;
    .....etc

//Setter Functions
void SetName (string x);
void SetRole(string x);
    void SetFFDefence(int x);
    ......etc
    };

PLAYER.CPP

Player::Player( string vName,
string vRole,
int vFFDefence,
......etc
{
Name = vName;
Role = vRole;
FFDefence = vFFDefence,
......etc
}
//getter functions
string Player::GetName() const {return Name; };
string Player::GetRole() const {return Role; };
int Player::GetFFDefence() const {return FFDefence; };
.....etc
//Setter Functions
void Player::SetName(string x) { Name = x ; };
void Player::SetRole(string x) { Role = x ; };
void Player::SetFFDefence(int x) { FFDefence = x ; };
......etc

So yeah - pretty bog standard......now I have a second class where one of the member functions is a Player Class itself.

BATTER.H

class Batter
{
private:
Player ID;
int Touch;
....etc

public:
Batter(Player vID, int vTouch = 0....etc);
//Getter Functions
string GetRole() const;
    int GetFFDefence() const;
    int GetBFDefence() const;....and so on.

OK - that's the code out of the way!!!!

So I've got it doing everything I want in terms of passing variables in and out....so I can create

Player Dave ("Dave", "Opener", 98, ....etc)

then later on (when I need it) create

Batter OnStrike (Dave, 10, .....etc)

All gravy....OK so I've started looking into inheritance and realized this is what I should be doing....back converting not a problem (did this with arrays and vectors the other day)...

Here's my problem:

With what I've got now, I can create "Player Dave" and then pass him into the subclass of Batter whenever I need to. How do I do the same with traditional inheritance? How do I take a specific instance (already created) of Player and use that as the parent for a specific instance of the child class Batter? As far as I can deduce at the moment, you need to create both at the same time.

Answer 1

Just initialize your base object with the object provided:

class Player
{
  Player(Player const&); // copy constructor (might be implicitly generated)
  ...
};

class Batter:
  public Player
{
  Batter(Player const& p, other arguments):
    Player(p),
    ...
  {
    ...
  }
};

On the other hand, there's the question whether inheritance of Batter from Player is the right tool in your case. The fact that you pass a Player object to construction hints at the fact that a Player may become a batter, and maybe later also stop being a batter. That is, Batter is actually a role which the player may temporarily have. Therefore it may be a better idea to separate the Player object from the role, by having a separate Role hierarchy where Batter and Pitcher derive from Role, and Player has a method which returns the current role, and another which can assign another role to the player.