某個對象構造的時候講自己註冊到一個單例的管理者

我們常常會在某個對象構造的時候講自己註冊到一個單例的管理者上去，這是很常見的一種設計模式。

這個管理者可以對外提供一些訪問管理這些對象的方式，還要負責管理者銷燬的時候，釋放掉那些對象

比如cocos2d-x中的PoolManager和AutoreleasePool之間就是這樣的一種關係。

 

#include<iostream>
#include<vector>
using namespace std;

class Delegate;

class ItemManager
{
public:
    static ItemManager* getInstance();

    void addDelegates(Delegate* delegate)
    {
        cout << "addDelegates" << endl;
        m_Delegates.push_back(delegate);
    }

    void trigger();

public:

vector<Delegate*>  m_Delegates;

private:
    ItemManager()
    {

    }

    static ItemManager* m_managerInstance;
};

 

ItemManager* ItemManager::m_managerInstance= NULL;

ItemManager* ItemManager::getInstance()
{
    if(m_managerInstance== NULL)
    {
        m_managerInstance = new ItemManager();
    }

    return m_managerInstance;
}

class Delegate
{
  public:

    Delegate()
    {
        cout << "constructor in Delegate" << endl;
        ItemManager::getInstance()->addDelegates(this);
    }

    virtual void action()
    {
        cout << " action in Delegate" << endl;
    }

};

void ItemManager::trigger()
{
    cout << "trigger" << endl;
    cout << "m_Delegates.size() " << m_Delegates.size() << endl;
    for(int i = 0 ; i < m_Delegates.size(); i++)
    {
        (m_Delegates[i])->action();
    }
}

class DelegateDerive : public Delegate
{
public:
    DelegateDerive()
    {
        cout << "constructor in delegate derive" << endl;
    }

    virtual void action()
    {
        cout << " action in DelegateDerive" << endl;
    }
};

class DelegateDerive2 : public Delegate
{
public:
    DelegateDerive2()
    {
        cout << "constructor in delegate derive2" << endl;
    }

    virtual void action()
    {
        cout << " action in DelegateDerive2" << endl;
    }
};

int main(int argc, char** argv)
{
    DelegateDerive* pDelegateDervie = new DelegateDerive();

    DelegateDerive2* pDelegateDervie2 = new DelegateDerive2();

    ItemManager::getInstance()->trigger();

    return 0;
}