C++ vector with dynamic item size

Question

the C++ STL vector has a lot of decent properties, but only works when the size of each item is known at run-time.

I would like to have a vector class that features

Answer 1

Use std::vector where item is a wrapped smart pointer. The "item" class make a pointer look like a plain value :

class item {
private:
    boost:unique_ptr p;
public:
    // ...
    public item(item that);

    public int someFunction() {
       // Forwarded
       return p->somefunction();
    }
};

class base {
    virtual ~base();
    // This is needed in order to implement copy of the item class
    virtual base* clone();
};

public item::item(item that) : p(that.p.clone()) {}

class some_real_type() : public base {
   // ....
}