Cfrtjryk

Here's code I wrote just to learn interfaces in C++ (could be presented as program which represents some units in rpg)

IUnit is interface for Unit

GroundUnit represents ground unit which can attack other units

AirUnit same as ground unit

#include <iostream>



class Enemy;



class IUnit {

public:

    virtual void hit(IUnit&) = 0;

    virtual void setHp(short) = 0;

    virtual short hp() const = 0;

    virtual ~IUnit();

};



IUnit::~IUnit() {



}



class GroundUnit : public IUnit {

private:

    short m_hp;

    short m_damage;

    short m_coeff;

public:

    GroundUnit(short hp, short damage, short coeff)

        : m_hp(hp)

        , m_damage(damage)

        , m_coeff(coeff)

    {}

    void hit(IUnit& unit) override;

    short hp() const override;

    bool dead() const { return m_hp < 1;}

    void setHp(short) override;



};



class AirUnit : public IUnit {

private:

    short m_hp;

    short m_damage;

public:

    AirUnit(short hp, short damage)

        : m_hp(hp)

        , m_damage(damage)

    {}

    void hit(IUnit& unit) override;

    short hp() const override;

    void setHp(short) override;

    bool dead() const { return m_hp < 1;}

};



void AirUnit::hit(IUnit& unit)

{

    unit.setHp(unit.hp() - m_damage);

}



short AirUnit::hp() const

{

    return m_hp;

}



void AirUnit::setHp(short newHp)

{

    m_hp = newHp;

}





void GroundUnit::hit(IUnit& unit)

{

    unit.setHp(unit.hp() - m_damage * m_coeff);

}



short GroundUnit::hp() const

{

    return m_hp;

}



void GroundUnit::setHp(short newHp)

{

    m_hp = newHp;

}



int main() {

    GroundUnit groundUnit1(100, 2, 2);

    GroundUnit groundUnit2(100, 2, 3);

    AirUnit airUnit1(100, 7);

    AirUnit airUnit2(100, 4);



    groundUnit1.hit(airUnit1);

    groundUnit2.hit(groundUnit1);

    airUnit1.hit(groundUnit1);

}

I know this is pretty short code but I would like to be sure if I am doing it right. Let's say

1. I want interface, so all methods must be pure virtual (right now). I guess this is bad case for interface because methods such as hp() are same in both Derived Classes.


2. 
   

   I want abstract class so methods can be implemented in IUnit class

   
   
   

   2.1. Here I would like to (probably) have method dead() implemented in Abstract Class so Abstract Class must know the Unit hp . How
   could it be done?

   
   

I would like to know some "rules of thumb" what should (not) be in Interface/Abstract Class