Modern C++ Design Pattern/Chatper 8. 컴포지트

created : 2020-04-07T11:44:17+00:00
modified : 2020-09-26T14:20:37+00:00
cpp composite

Composite Pattern

Properties based on array.

  class Creature
  {
    int strength, agility, intelligence;
  public:
    int get_stringth() const
    {
      return strength;
    }

    void set_strength(int strength)
    {
      Creture::strength = strength;
    }
    // Other getter/setter....
    int sum() const {
      return strength + agility + intelligence;
    }

    double average() const {
      return sum() / 3.0;
    }

    int max() const {
      return ::max(::max(strength, agility), intelligence);
    }
  };
  class Creature
  {
    enum Abilitis { str, agl, intl, count };
    array<int, count> abilities;
    int get_strength() const { return abilities[str]; }
    void set_strength(int value) { abilities[str] = value; }
    // Other getter/setter ...

    int sum() const {
      return accumulate(abilities.begin(), abilities.end(), 0);
    }

    double average() const {
      return sum() / (double) count;
    }

    int max() const {
      return *max_element(abilities.begin(), abilities.end());
    }
  };

Grouping

    struct GraphicObject
    {
      virtual void draw() = 0;
    };

    struct Circle : GraphicObject
    {
      void draw() override
      {
        cout << "Circle" << endl;
      }
    };

    struct Group : GraphicObject
    {
      string name;

      explicit Group(const string& name)
        : name{name} {}

      void draw() override
      {
        cout << "Group " << name.c_str() << " containes:" << endl;
        for (auto&& o : objects)
          o->draw();
      }

      vector<GraphicObject*> objects;
    };

    Group root("root");
    Circle c1, c2;
    root.objects.push_back(&c1);

    Group subgroup("sub");
    subgroup.objects.push_back(&c2);

    root.objects.push_back(&subgroup);

    root.draw();