cleak

typedef void(VoidMemberFn)(void*);

VoidMemberFn* fn = (VoidMemberFn*)GetVTable<BaseType>(my_obj_ptr)[1];

// ... sometime later

fn(my_obj_ptr);

cleak

template <typename T>
void** GetVTable(T* obj) {
  return *((void***)obj);
}

cleak

class BouncyBall : public GameObject {
  void Update() override {
    // ...
  }
  
  void PhysicsUpdate() override {
    // ...
  }
};

cleak

class SceneManager {
 public:
  SceneManager() {
    null_vtable_ = GetVtable(&null_object_);
  }

  void Add(SceneObject* obj) {
    SceneObject_VTable* vtable = GetVtable(obj);

    if (vtable->update != null_vtable_->update) {

cleak

class SceneObject {
 public:
  virtual ~SceneObject() {}
  virtual void Update() {}
  virtual void LateUpdate() {}
  virtual void PhysicsUpdate() {}
  virtual void DrawImmediate() {}
};

struct SceneObject_VTable {

cleak

typedef void (UpdateFn)(void*);

struct CompareUpdateFns {
  bool operator()(const std::pair<UpdateFn*, void*>& a,
                  const std::pair<UpdateFn*, void*>& b) const {
    if (a.first == b.first) {
      return a.second < b.second;
    }
    return a.first < b.first;
  }

cleak

class IncrementerBase {
 public:
  IncrementerBase() {
    my_num = rand();
  }
  virtual ~IncrementerBase() {}
  virtual void Increment() {}
  int my_num;
};

cleak

GenericGreeter_VTable* GetVTable(GenericGreeter* obj) {
  GenericGreeter_VTable** vtable_ptr = (GenericGreeter_VTable**)obj;
  return *(vtable_ptr);
}

cleak

typedef void (GreetFn)(void*, const char* name);
struct GenericGreeter_VTable {
  GreetFn* greet;
  GreetFn* dismiss;
};

cleak

class GenericGreeter {
 public:
  virtual void Greet(const char* name) {
    cout << "Hi " << name << "." << endl;
  }

  virtual void Dismiss(const char* name) {
    cout << "Bye " << name << "." << endl;
  }
};