我有这样的事情:
enum EFood{
eMeat,
eFruit
};
class Food{
};
class Meat: public Food{
void someMeatFunction();
};
class Fruit: public Food{
void someFruitFunction();
};
class FoodFactory{
vector<Food*> allTheFood;
Food* createFood(EFood foodType){
Food* food=NULL;
switch(foodType){
case eMeat:
food = new Meat();
break;
case eFruit:
food = new Fruit();
break;
}
if(food)
allTheFood.push_back(food);
return food;
}
};
int foo(){
Fruit* fruit = dynamic_cast<Fruit*>(myFoodFactory->createFood(eFruit));
if(fruit)
fruit->someFruitFunction();
}
现在我想更改我的应用程序以使用 boost shared_ptr 和 weak_ptr 以便我可以在一个地方删除我的食物实例。它看起来像这样:
class FoodFactory{
vector<shared_ptr<Food> > allTheFood;
weak_ptr<Food> createFood(EFood foodType){
Food* food=NULL;
switch(foodType){
case eMeat:
food = new Meat();
break;
case eFruit:
food = new Fruit();
break;
}
shared_ptr<Food> ptr(food);
allTheFood.push_back(ptr);
return weak_ptr<Food>(ptr);
}
};
int foo(){
weak_ptr<Fruit> fruit = dynamic_cast<weak_ptr<Fruit> >(myFoodFactory->createFood(eFruit));
if(shared_ptr<Fruit> fruitPtr = fruit.lock())
fruitPtr->someFruitFunction();
}
但问题是 dynamic_cast 似乎不适用于 weak_ptr
如果我知道它指向的对象是派生类型,我该如何weak_ptr<Fruit>
摆脱它?weak_ptr<Food>