Design Patterns : Abstract Factory

Abstract Factory is a kind of Structural Design Pattern.
Solves the problem of creating instances of entire product families without specifying their concrete class.

Frequency of use: 5/5 (High)

Intent:
Provides an interface for creating families of related or dependent objects without specifying their concrete classes.
The new operator is considered harmful

Problem:


Solution:

• Explicitly declare interfaces for each distinct product of the product family
• Make all variants of that product follow those interfaces
• Create an abstract factory which returns abstract product type represented by the interface

UML Class Diagram:


Code:

 
using System;

namespace AbstractFactory
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("This is Abstract Factory");
            Console.ReadLine();
        }
    }

    #region FamilyOfProducts
    abstract class Button
    {
        public abstract void Paint();
    }

    class WindowsButton : Button
    {
        public override void Paint()
        {
            Console.WriteLine("Paint() called of Windows Button");
        }
    }

    class MacButton : Button
    {
        public override void Paint()
        {
            Console.WriteLine("Paint() called of Mac Button");
        }
    }

    abstract class CheckBox
    {
        public abstract void Paint();
    }

    class WinCheckBox : CheckBox
    {
        public override void Paint()
        {
            Console.WriteLine("Paint() called of Windows CheckBox");
        }
    }

    class MacCheckBox : CheckBox
    {
        public override void Paint()
        {
            Console.WriteLine("Paint() called of Mac CheckBox");
        }
    }
    #endregion FamilyOfProducts

    #region AbstractFactory & ConcreteFactory
    abstract class GUIFactory
    {
        public abstract Button CreateButton();
        public abstract CheckBox CreateCheckBox();
    }

    class WinFactory : GUIFactory
    {
        public override Button CreateButton()
        {
            return new WindowsButton();
        }

        public override CheckBox CreateCheckBox()
        {
            return new WinCheckBox();
        }
    }

    class MacFactory : GUIFactory
    {
        public override Button CreateButton()
        {
            return new MacButton();
        }

        public override CheckBox CreateCheckBox()
        {
            return new MacCheckBox();
        }
    }
    #endregion AbstractFactory


    class Application
    {
        private GUIFactory _factory;
    }
}