samedi 21 novembre 2015

How to use shared_ptr in a decorator pattern implementation correctly?

I am getting memory leak issues in the following code. I understand there are some flows. But not sure. How to use shared_ptr in these scenarios? And in case I need to add more decorators, say Chocolate-Pista-Icecream, how to pass the pointer correctly such that it will get deleted at the exit?

    class AbstractCream
{
public:
    virtual void ShowFlavour() = 0;
    virtual ~AbstractCream()
    {
        cout << endl << "AbstractCream-DTOR";
    }
};

class IceCream :public AbstractCream
{
public:
    void ShowFlavour()
    {
        cout << "IceCream";
    }
    ~IceCream()
    {
        cout << endl << "IceCream Dtor";
    }
};

class DecoratorCream :public AbstractCream
{
private:
    std::shared_ptr<AbstractCream> AbCream;
public:
    DecoratorCream(std::shared_ptr<AbstractCream>abs) :AbCream(abs)
    {}
    void ShowFlavour()
    {
        AbCream->ShowFlavour();
    }
    virtual ~DecoratorCream()
    {
        cout << endl << "DecoratorCream-DTOR";

    }
};

class ChocolateCream : public DecoratorCream
{
public:
    ChocolateCream(std::shared_ptr<AbstractCream>abs) :DecoratorCream(abs)
    {}
    void ShowFlavour()
    {
        cout << "CholocateCream added..";
        DecoratorCream::ShowFlavour();
    }
    ~ChocolateCream()
    {
        cout << endl << "ChocolateCream-DTOR";
    }

};
class PistaCream : public DecoratorCream
{
public:
    PistaCream(std::shared_ptr<AbstractCream> abs) :DecoratorCream(abs)
    {}
    void ShowFlavour()
    {
        cout << "PistaCream added..";
        DecoratorCream::ShowFlavour();
    }
    ~PistaCream()
    {
        cout << endl << "PistaCream-DTOR";
    }
};

class StrawberryCream : public DecoratorCream
{
public:
    StrawberryCream(std::shared_ptr<AbstractCream> abs) :DecoratorCream(abs)
    {}
    void ShowFlavour()
    {
        cout << "StrawberryCream added..";
        DecoratorCream::ShowFlavour();
    }
    ~StrawberryCream()
    {
        cout << endl << "StrawberryCream-DTOR";
    }
};


int main()
{
    std::shared_ptr <AbstractCream> ice1( new IceCream());
    std::shared_ptr <PistaCream> pista1(new PistaCream(ice1));
    std::shared_ptr <AbstractCream> ice2(new IceCream());
    std::shared_ptr <ChocolateCream>choco1( new ChocolateCream(ice2));

    pista1->ShowFlavour();
    cout << endl;
    choco1->ShowFlavour();
    cout << endl;

    getchar();
    _CrtDumpMemoryLeaks();
    return 0;
}

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