More simple way to access derived properties & methods given base pointer

Question

Right now, I have this code, and it is working as expected. In order to set properties of object type Cannon when given the base type Defense*, I am casting Cannon* to it and using that to set the properties.

void fillProperties(Defense* defense)
{
    if (defense->getType() == "Cannon")
    {
        Cannon* c = (Cannon*)defense;
        double cannonBallDamage, cannonBallSpeed, blastRadius;

        cout << "Cannon ball damage (hp): ";
        cin >> cannonBallDamage;
        cout << "Cannon ball speed (ft/sec): ";
        cin >> cannonBallSpeed;
        cout << "Blast radius (ft): ";
        cin >> blastRadius;

        c->setBlastRadius(blastRadius);
        c->setCannonBallDamage(cannonBallDamage);
        c->setCannonBallSpeed(cannonBallSpeed);
    }
}

The setBlastRadius, setCannonBallDamage, and setCannonBallSpeed methods exist only inside Cannon, not in Defense. I have 6 different types of classes that derive from Defense with their own extra properties, Cannon being one.

My question is: is there a more simple way than checking the type of the object and creating a new (casted) pointer for each one to set its properties?

Answer 1

You can add virtual method in Defense:

class Defense
{
public:
    virtual ~Defense()
    virtual void fillProperties() = 0;
    // [...]
};

class Canon : public Defense
{
public:
    virtual void fillProperties() override
    {
        cout << "Cannon ball damage (hp): ";
        cin >> this->cannonBallDamage;
        cout << "Cannon ball speed (ft/sec): ";
        cin >> this->cannonBallSpeed;
        cout << "Blast radius (ft): ";
        cin >> this->blastRadius;
    }
    // [...]

private:
    double cannonBallDamage, cannonBallSpeed, blastRadius;
};

Visitor pattern can be used to avoid to add too many methods in Defense