C++ Pointer Lists and passage by reference

Question

On the code below, do I need to create an instance of my list when I use the constructor in ClassWithList?

Also, why is addToList wrong? How can I achieve that?

class AbstClass;
class ObjClass : AbstClass;

class ClassWithList
{
    std::list<AbstClass*> absts;
public:
    ClassWithList(); //new list?
    void addToList(ObjClass& obj)
    {
        list.push_back(obj);
    }



};

Answer 1

You have to do some simple corrections (explanations in comments):

class AbstClass;
class ObjClass : public AbstClass; // << You need to derive as public

class ClassWithList
{
    std::list<const AbstClass *> absts;
public:
    ClassWithList(); // You don't need new list, it will be allocated 
                     // already correctly at construction
    void addToList(const AbstClass& obj)
    {
        absts.insert(&obj); // << pass the address
     // ^^^^^ The member is named absts
    }
};