04-inheritance.md

Dziedziczenie

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Kolejność wywołań konstruktorów i destruktorów

• Konstruktory - najpierw klasa bazowa, potem pochodna
• Destruktory - zawsze w odwrotnej kolejności niż konstruktory
• Birthday cake

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Co wyświetli się na ekranie?

#include <iostream>

using namespace std;

class Chocolate {
public:
    Chocolate()  { cout << "Chocolate ctor" << endl; }
    ~Chocolate() { cout << "Chocolate dtor" << endl; }
};

class ChocolateCake {
public:
    ChocolateCake()  { cout << "ChocolateCake ctor" << endl; }
    ~ChocolateCake() { cout << "ChocolateCake dtor" << endl; }
private:
    Chocolate chocolate;
};

class Candles {
public:
    Candles()  { cout << "Candles ctor" << endl; }
    ~Candles() { cout << "Candles dtor" << endl; }
};

class BirthdayCake : public ChocolateCake {
public:
    BirthdayCake()  { cout << "BirthdayCake ctor" << endl; }
    ~BirthdayCake() { cout << "BirthdayCake dtor" << endl; }
private:
    Candles candles;
};

int main(int argc, char *argv[]) {
    BirthdayCake birthdayCake;
    return 0;
}

Napisz w komentarzu 🙂

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private czy public?

• Dziedziczenie class po struct jest...?

  struct A { int a; };
  class B : A {};
  int main() {
      B item;
      item.a = 5;
  }

  • private
  • error: ‘int A::a’ is inaccessible within this context

---

private czy public?

• Dziedziczenie struct po class jest...?

  class A {
  public:
      int a;
  };
  struct B : A {};
  
  int main() {
      B item;
      item.a = 5;
  }

  • public

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Inheritance access modifiers

	public	protected	private
public	public	protected	private
protected	protected	protected	private
private	private	private	private

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Problem diamentowy

                            A               Animal
                           / \             /      \
                          B   C         Mammal   Fish
                           \ /             \      /
                            D               Dolphin

• Deadly Diamond of Death
• Wirtualne dziedziczenie
  • class B : virtual public A
  • class C : virtual public A
  • class D : virtual public B, virtual public C