问类Unity3D组件系统

EN

#include <iostream>
#include <vector>

class GameObject;

class Component
{
private:
    GameObject * parent;

public:
    Component(GameObject * parent = nullptr)
    {
        this->parent = parent;
    }

    virtual ~Component() { parent = nullptr; }

    GameObject* GetParent() { return parent; }

    void SetParent(GameObject* parent) { this->parent = parent; }

    virtual std::string What() { return "Basic Component"; }
};

class SoundSource : public Component
{
private:
    // some sound specific members

public:
    SoundSource(GameObject * parent = nullptr) : Component(parent) {}

    virtual ~SoundSource() { }

    std::string What() { return "SoundSource Component"; }
};

class GameObject
{
private:
    std::vector<Component*> m_Components;

public:
    GameObject() :
        m_Components()
    {}

    ~GameObject()
    {
        for (size_t i = 0; i < m_Components.size(); ++i)
            if (m_Components[i]->GetParent() == this) delete m_Components[i];
        m_Components.clear();
    }


    void AddComponent(Component* comp)
    {
        if (comp->GetParent() == nullptr)
        {
            comp->SetParent(this);
        }
        m_Components.push_back(comp);
    }

    template <class component_type>
    component_type* GetComponent()
    {
        for (auto comp : m_Components)
        {
            component_type* c =  dynamic_cast<component_type*>(comp);
            if (c) return c;
        }
        return nullptr;
    }
};

int main()
{
    GameObject go;
    go.AddComponent(new SoundSource());
    go.AddComponent(new Component());

    SoundSource *s = go.GetComponent<SoundSource>();
    if (s) std::cout << s->What() << std::endl;
}