C++: Inheriting from std::map

Question

I want to inherit from std::map, but as far as I know std::map hasn't any virtual destructor.

Is it therefore possible to call std::map's destructor explicitly in my destructor to ensure proper object destruction?

Answer 1

The destructor does get called, even if it's not virtual, but that's not the issue.

You get undefined behavior if you attempt to delete an object of your type through a pointer to a std::map.

Use composition instead of inheritance, std containers are not meant to be inherited, and you shouldn't.

I'm assuming you want to extend the functionality of std::map (say you want to find the minimum value), in which case you have two far better, and legal, options:

1) As suggested, you can use composition instead:

template<class K, class V>
class MyMap
{
    std::map<K,V> m;
    //wrapper methods
    V getMin();
};

2) Free functions:

namespace MapFunctionality
{
    template<class K, class V>
    V getMin(const std::map<K,V> m);
}