Module 03 Solutions

Download Module 03 Solutions

Exercise 00: ClapTrap

Base class with protected attributes for inheritance.

ClapTrap.hpp

class ClapTrap {
protected:
    std::string _name;
    int         _hitPoints;     // 10
    int         _energyPoints;  // 10
    int         _attackDamage;  // 0

public:
    ClapTrap(std::string name);
    ClapTrap(const ClapTrap& other);
    ClapTrap& operator=(const ClapTrap& other);
    ~ClapTrap();

    void attack(const std::string& target);
    void takeDamage(unsigned int amount);
    void beRepaired(unsigned int amount);
};

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Exercise 01: ScavTrap

Inherits from ClapTrap with different values.

ScavTrap.hpp

class ScavTrap : public ClapTrap {
public:
    ScavTrap(std::string name);
    ScavTrap(const ScavTrap& other);
    ScavTrap& operator=(const ScavTrap& other);
    ~ScavTrap();

    void attack(const std::string& target);  // Override
    void guardGate();                        // New ability
};

ScavTrap.cpp

ScavTrap::ScavTrap(std::string name) : ClapTrap(name) {
    std::cout << "ScavTrap " << _name << " constructed" << std::endl;
    _hitPoints = 100;
    _energyPoints = 50;
    _attackDamage = 20;
}

Key Point: Call base constructor in initialization list, then override values.

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Exercise 03: DiamondTrap

Virtual inheritance to solve the diamond problem.

ScavTrap.hpp

class ScavTrap : virtual public ClapTrap {
    // virtual keyword prevents duplicate ClapTrap
};

FragTrap.hpp

class FragTrap : virtual public ClapTrap {
    // virtual keyword prevents duplicate ClapTrap
};

DiamondTrap.hpp

class DiamondTrap : public ScavTrap, public FragTrap {
private:
    std::string _name;  // Own name (shadows ClapTrap::_name)

public:
    DiamondTrap(std::string name);
    ~DiamondTrap();

    using ScavTrap::attack;  // Use ScavTrap's attack
    void whoAmI();
};

DiamondTrap.cpp

DiamondTrap::DiamondTrap(std::string name)
    : ClapTrap(name + "_clap_name"),  // Initialize virtual base
      ScavTrap(name),
      FragTrap(name),
      _name(name)
{
    _hitPoints = FragTrap::_hitPoints;      // 100
    _energyPoints = ScavTrap::_energyPoints; // 50
    _attackDamage = FragTrap::_attackDamage; // 30
}

void DiamondTrap::whoAmI() {
    std::cout << "I am " << _name << std::endl;
    std::cout << "My ClapTrap name is " << ClapTrap::_name << std::endl;
}