在C ++中将派生类对象添加到bas类对象的向量中？

Question

I have not used this c++ feature since a long time, so have just forgotten about it. Suppose I have a class called "object", and a class "button", which is publicly derived from "object".

Now, consider i have a vector a, or a hash_map a. Will I be able to add objects of type "button: in it? or in fact any other class objects publicly derived from "object". How can I do this?

Thanks

Answer 1

Use a vector of pointers:

struct Base
{
    virtual ~Base() {}
    virtual int foo() = 0;   // good manners: non-leaf classes are abstract
};

struct Derived1 : Base { /* ... */ };
struct Derived2 : Base { /* ... */ };
struct Derived3 : Base { /* ... */ };

#include <vector>
#include <memory>

int main()
{
    std::vector<std::unique_ptr<Base>> v;

    v.emplace_back(new Derived3);
    v.emplace_back(new Derived1);
    v.emplace_back(new Derived2);

    return v[0]->foo() + v[1]->foo() + v[2]->foo();  // all highly leak-free
}