C++ shared_ptr vs. unique_ptr for resource management

Question

I\'ve been mulling over use of unique_ptr vs shared_ptr vs own_solution. I\'ve discounted the latter as I\'ll almost certainly get it

Answer 1

So I suppose what I'm looking for is a deferencable weak_ptr that cannot be converted into a shared_ptr.

You could hand out your one little helper class:

template
class NonConvertibleWeakPtr
{
public:
   NonConvertibleWeakPtr(const std::shared_ptr& p) : p_(p) {}
   ... // other constructors / assignment operators
   bool expired() const { return p_.expired(); }
   T* operator->() const { return get(); }
   T& operator*() const { return *get(); }
private:
   T* get() const { return p_.lock().get(); }
private:
   std::weak_ptr p_;
};

This is slightly better than a raw pointer, because you can check if your pointer is still valid.

Example usage:

std::shared_ptr sp = std::make_shared(5);
{
    NonConvertibleWeakPtr wp(sp);
    if(!wp.expired()) {
        std::cout << *wp << std::endl;
    }
}

However a user can still misuse it for example with std::shared_ptr blah(&(*wp));, but it takes a bit more criminal energy.