Wrapping a releaseable object into a smart pointer

Question

As far as I understand the smart pointers, they are there to avoid memory leaks among other things. However there are often objects which also need to be released, but not by

Answer 1

If you are using unique_ptr or shared_ptr, you can provide your custom deleter. The deleter for a unique_ptr is passed as a template parameter, and

Deleter must be FunctionObject or lvalue reference to a FunctionObject or lvalue reference to function, callable with an argument of type unique_ptr::pointer

For the shated_ptr, the deleter should be provided as the constructor parameter.

class Foo
{

};

class Deleter
{
public:
    void operator()(Foo *)
    {
        std::cout << "deleter";
    }
};

int main() {
    std::unique_ptr ptr(new Foo());
    std::shared_ptr ptr1(new Foo(),
                             [](Foo*){std::cout << "deleter for shared_ptr";}
                             );
}

You have to be careful not to cause memory leaks, though.