Example of `abstract factory' design pattern in C++

abstract_factory_example.cpp

/*
 * Example of `abstract factory' design pattern.
 * Copyright (C) 2011 Radek Pazdera

 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.

 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.

 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include <iostream>
#include <string>

class Window
{
    protected:
        int width;
        int height;
        std::string toolkit;
        std::string type;

        Window(std::string usedToolkit, std::string windowType)
            : toolkit(usedToolkit), type(windowType)
        {}

    public:
        std::string getToolkit()
        {
            return toolkit;
        }

        std::string getType()
        {
            return type;
        }
};

class GtkToolboxWindow : public Window
{
    public:
        GtkToolboxWindow()
            : Window("Gtk", "ToolboxWindow")
        {}
};

class GtkLayersWindow : public Window
{
    public:
        GtkLayersWindow()
            : Window("Gtk", "LayersWindow")
        {}
};

class GtkMainWindow : public Window
{ 
    public:
        GtkMainWindow()
            : Window("Gtk", "MainWindow")
        {}
};


class QtToolboxWindow : public Window
{
    public:
        QtToolboxWindow()
            : Window("Qt", "ToolboxWindow")
        {}
};

class QtLayersWindow : public Window
{
    public:
        QtLayersWindow()
            : Window("Qt", "LayersWindow")
        {}
};

class QtMainWindow : public Window
{
    public:
        QtMainWindow()
            : Window("Qt", "MainWindow")
        {}
};


/* This is the abstract factory. */
class UIFactory
{
    public:
        virtual Window* getToolboxWindow() = 0;
        virtual Window* getLayersWindow() = 0;
        virtual Window* getMainWindow() = 0;

};

/* Factory for Gtk toolkit */
class GtkUIFactory : public UIFactory
{
    public:
        Window* getToolboxWindow()
        {
            return new GtkToolboxWindow();
        }

        Window* getLayersWindow()
        {
            return new GtkLayersWindow();
        }

        Window* getMainWindow()
        {
            return new GtkMainWindow();
        }
};

/* Factory for Qt toolkit */
class QtUIFactory : public UIFactory
{
    public:
        Window* getToolboxWindow()
        {
            return new QtToolboxWindow();
        }

        Window* getLayersWindow()
        {
            return new QtLayersWindow();
        }

        Window* getMainWindow()
        {
            return new QtMainWindow();
        }
};

int main()
{
    UIFactory* ui = 0;

    /* Check what environment is running
       and create appropriate factory. */
    if (/* Gtk == */ true)
    {
        ui = new GtkUIFactory();
    }
    else
    {
        ui = new QtUIFactory();
    }

    /* Use the factory to build interface. */
    Window* toolbox = ui->getToolboxWindow();
    Window* layers  = ui->getLayersWindow();
    Window* main    = ui->getMainWindow();

    /* See what have we recieved. */
    std::cout << toolbox->getToolkit() << ":"
              << toolbox->getType() << std::endl;

    std::cout << layers->getToolkit() << ":"
              << layers->getType() << std::endl;

    std::cout << main->getToolkit() << ":"
              << main->getType() << std::endl;
}

Nice example!

After Window* toolbox = ui->getToolboxWindow(); line
It calls return new QtToolboxWindow(); line.
It allocate memory and return which store in toolbox pointer in main function.
How can I delete this and who is responsible for deallocate the memory.
what is the delete procedure.
Is it create the memory leakage issue???

@erfanhossainshoaib : It looks like leaks to me. One way to solve this is to store these pointers in RAII auto pointers like this : std::unique_ptr<Window> toolbox(ui->getToolboxWindow(););

Very interesting example tanks you.