How can I have several inherited classes together in the same array?

Question

I have a few classes, ObjDef, PeopDef, NpcDef, and PlyDef, such that PlyDef and NpcDef each seperately inherit PeopDef, and PeopDef inherits ObjDef. Each class has functionality that builds on the class before it, so it's important that PeopDef::Tick is called before ObjDef::Tick. I have every object stored in a vector<ObjDef> object, but when the main tick loop goes through them, I want them to call the original classes' Tick, rather than ObjDef::Tick, which is what the vector<ObjDef> currently makes it do. Is there any way to do this, or do I have to have a separate vector for each class?

Answer 1

You can store an ObjDef pointer (ObjDef* or a smart pointer) in the vector and make the Tick method virtual.

Here's an example:

#include <iostream>
#include <vector>
#include <memory>

class ObjDef
{
public:
    virtual void Tick()
    {
        std::cout << "ObjDef::Tick\n";
    }
};

class PeopDef : public ObjDef
{
public:
    virtual void Tick()
    {
        std::cout << "PeopDef::Tick\n";
    }
};

int main()
{
    std::vector<std::shared_ptr<ObjDef>> objects;

    std::shared_ptr<ObjDef> obj(new ObjDef());
    std::shared_ptr<ObjDef> peop(new PeopDef());

    objects.push_back(obj);
    objects.push_back(peop);

    for (auto object : objects)
    {
        object->Tick();
    }

    return 0;
}