Как предотвратить прямой вызов конструктора и деструктора производных классов в C++ ⇐ C++

[Гость]

I have an abstract class "Entity". I want to prevent manual calls to the constructor and destructor of its derived classes.

To create and destroy the instances of this class, I use the following function:

Код: Выделить всё

template  && std::is_constructible_v>> T* SpawnEntity(Args&&... args) {     T* instance = new T(std::forward(args)...);          // ... perform other operations ...          return instance; }      void Destroy(Entity* entity) { ... } 

Is it possible to throw an exception or a compile error if the constructor / destructor of any class that extends Entity is called manually?

Edit1: I cannot control all the derived classes of Entity, so I cannot define the constructors as private.

Edit2: My main goal is to prevent other programmers (and myself) from making mistakes. I couldn't find a way to prevent the constructors and destructors from being called directly, but I found a solution where I can print a warning message if the factory class isn't used:

Код: Выделить всё

class EntityFactory { private:     static inline int s_FactoryUsageDepth = 0;     friend class Entity; public:     template  && std::is_constructible_v>>     static T* SpawnEntity(Args&&... args)     {         s_FactoryUsageDepth++;         T* instance = new T(std::forward(args)...);         // ... perform other operations ...         return instance;     }     static void Destroy(Entity* entity)      {         s_FactoryUsageDepth++;         delete entity;         // ... perform other operations ...     } } class Entity {     protected:         Entity()          {              if (EntityFactory::s_FactoryUsageDepth-- == 0)             {                 // ... show an error message ...             }         }                  virtual ~Entity()          {             if (EntityFactory::s_FactoryUsageDepth-- == 0)             {                 // ... show an error message ...             }         } } 

I use an integer instead of a bool because the constructor of an Entity could call other constructors. I think this solution covers all cases, but let me know if there is something that I'm missing.

Edit3: Small fix in the code


Источник: https://stackoverflow.com/questions/781 ... being-call