C++でUnityのGetComponentのようなものを実装してみた

経緯

実行時型情報(RTTI)を使って何か書きたい

コンパイル環境

$ g++ --version
Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 9.0.0 (clang-900.0.39.2)
Target: x86_64-apple-darwin16.7.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

コンパイル、リンク

g++ main.cpp -o main -std=c++11

コード

#include <cstdio>
#include <string>
#include <iostream>
#include <list>

class Object
{
public:
    Object() {}
    virtual ~Object() {}

    static void Destroy(Object* obj)
    {
        if (obj != nullptr)
            delete obj;
    }
};

class GameObject;
class Component : public Object
{
public:
    Component() {}
    virtual ~Component() {}

    virtual void Print()
    {
        std::cout << "I am Component!" << std::endl;
    }

    GameObject* gameobject;
};

class Transform : public Component
{
public:
    Transform() {}
    virtual ~Transform() {}

    virtual void Print()
    {
        std::cout << "I am Transform!" << std::endl;
    }
};

class Text : public Component
{
public:
    Text() : text("I am Text") {}
    virtual ~Text() {}

    std::string text;

    virtual void Print()
    {
        std::cout << text << std::endl;
    }
};

class GameObject : public Object
{
public:
    GameObject()
    {
    }
    virtual ~GameObject()
    {
        for (Component* component : componentList_)
        {
            if (component != nullptr)
                Destroy(component);
        }
    }

    template <class T, bool isExtended = std::is_base_of<Component, T>::value> T* AddComponent()
    {
        static_assert(isExtended, "AddComponent<> : T is not inherited from Component Class");
        T* component = new T();
        componentList_.push_back(component);
        return component;
    }

    template <class T> T* GetComponent()
    {
        T* component;

        for (Component* c : componentList_)
        {
            component = dynamic_cast<T*>(c);
            if (component != nullptr)
                return component;
        }
        return nullptr;
    }


    void PrintComponentList()
    {
        transform_.Print();
        for (Component* component : componentList_)
        {
            component->Print();
        }
    }

private:
    std::list<Component*>   componentList_;
    Transform               transform_;
};
template <> Transform* GameObject::GetComponent()
{
    return &transform_;
}


int main()
{
    GameObject gameObject;

    Text* text1 = gameObject.AddComponent<Text>();
    Text* i = gameObject.GetComponent<Text>();

    gameObject.PrintComponentList();

    rewind(stdin);
    getchar();
    return 0;
}