如何从shared_ptr调用私有析构函数？

问题描述

我有一个 resource_manager 类，它维护一个 std :: vector< boost :: shared_ptr< resource> > 。 resource_manager 是 resource 的朋友类。我希望 resource 只能通过 resource_manager 创建/删除，所以我把它的构造函数私有。

I have a resource_manager class which maintains a std::vector<boost::shared_ptr<resource> > internally. resource_manager is a friend class of resource. I want resources to only be created/deleted by resource_manager, so I made its constructors private (which works ok).

但是，如果我使析构函数私有，代码不会编译，因为析构函数被调用 boost :: shared_ptr ，这不是 resource 的朋友。我想从 resource_manager 中只返回 const resource * ，强制执行 ，但不知何故我不满意这种方法提供的安全性（如果一个客户端发生在一个指向非const的指针）。

However, if I make the destructor private, the code doesn't compile because the destructor is called by boost::shared_ptr, which is not a friend of resource. I am thinking of enforcing the "do not delete by clients" rule by only returning only const resource* from the resource_manager, but somehow I am not satisfied with the security this method provides (what if a client somehow happens across a pointer to non-const?)

除了明显的解决方案没有使用 shared_ptr ，您有任何解决方法/更好的解决我的问题吗？

Apart from the obvious solution of not using shared_ptr, do you have any workaround / better solution to my problem?

推荐答案

您可以将自定义删除程序传递给共享指针。所以只需创建一个删除函子或函数（由你决定），然后依次是你的类的朋友：

You can pass a custom deleter to the shared pointer. So just create a deleter functor or function (up to you) which in turn is a friend of your class:

class Secret
{
  ~Secret() { }
  friend class SecretDeleter;
  friend void SecretDelFunc(Secret *);
};

class SecretDeleter
{
public:
  void operator()(Secret * p) { delete p; }
};

void SecretDelFunc(Secret * p) { delete p; }

std::shared_ptr<Secret> sp1(new Secret, SecretDeleter());
std::shared_ptr<Secret> sp2(new Secret, SecretDelFunc);

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