Creational design pattern using C#

Sourav.Kayal
Posted by in C# category on for Intermediate level | Points: 250 | Views : 2380 red flag

This article is related to creational design pattern in c# programming language

Introduction to design pattern.And why it needed ?.

Let me start with very interesting quote” It’s easy to walk on water and develop software from specification- if both are frozen.” –means what?  Yes, I think you already guess it. I am talking about requirement change of software development. And for that design pattern is very necessary.It will help you to construct very strong foundation in software project.  

In this article I am going to explain few very popular design patterns in software development process. I will explain and show code in C# but you may use your favorite programming language to implement them. Basically there are three categories in design pattern

1) Creational

2) Behavioral

3) Structural

Let’s get common fundamental idea about them.

Creational:- It deals with object creation in your project . Define how your object will get create? When it will get create? where it will get create?.

Behavioral:- It defines behavior of your code or class. Means it will deal with how one object will communicate with other. How we will preserver object’s state any many more.

Structural:- Basically  structural design pattern deals with or define structure of your project . How to implement de couple relation within class? How to implement common pattern or naming convention throughout project?etc.

And here I am going to explain Creational design pattern

Few popular example of creational design pattern are

Factory design pattern

Prototype design pattern

Singleton design pattern

Now let’s discuss one by one with example.

Factory Design pattern

Factory design pattern is one of the common design patterns in software project. Let’s understand the basics of Factory design pattern.

Before starting the discussion, let’s learn the advantage of Factory design pattern.  

<!--[if !supportLists]-->1)      <!--[endif]-->In client code here and there we create object using new keyword within much more if – else condition. If you implement factory design pattern to reduce new keyword in client.

<!--[if !supportLists]-->2)      <!--[endif]-->When you want to abstract your business class from client, then implement factory pattern in your project in project.

In below code below, we see how to implement factory design pattern in project. Here we have two types of employee class in my code and I have created a factory class EmployeeFactory to supply object of appropriate class depending upon class request . Now if you add one more type of employee class in your business logic the client should not bother at all. Just tell your client to send proper code to get object of newly added class.

So basically our factory class is making an abstraction over our business class.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
using System.Data.SqlClient;
using System.Data;
using System.Diagnostics;
 
namespace BlogProject
{
    // Factory Design patern
    public interface IEmployee
    {
        void ShowEmployee();
    }
    public class Developer:IEmployee
    {
        public void ShowEmployee()
        {
            Console.Write("I ma .NET Developer");
        }
    }
 
    public class HR : IEmployee
    {
        public void ShowEmployee()
        {
            Console.Write("I am Technical HR");
        }
    }
 
    public class EmployeeFactory
    {
        // Factory class to generate object of concrite class
        public IEmployee GetObject(int a)
        {
            if (a == 1)
            {
                return new Developer();
            }
            else if (a == 2)
            {
                return new HR();
            }
            else
                return null;
        }
 
    }
 
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Enter 1 to create Developer class object and 2 to create HR class object"+"\n");
            int Type = Convert.ToInt32(Console.ReadLine());
            EmployeeFactory objFactory = new EmployeeFactory();
            IEmployee objemp = objFactory.GetObject(Type);
            objemp.ShowEmployee();
            Console.ReadLine();
        }
    }
}

Singleton design pattern

By seeing the name you probably guess that it’s something related to single object, right? If you guess so, then you are master of design pattern, just kidding. OK, I know you are learning design pattern and one day you will be among the best.

 

So coming to our discussion again. Singleton design pattern is one of very essential design pattern in day to day programming life. Are you thinking, where it needs to be implemented? If you still do not find any example let me give one.

 

In website you might be aware of hit count feature. So whenever any user visits the website (with hit counter feature) the hit count variable increase by one. It’s one wonderful example of singleton pattern.

 

So what happens exactly? In whole project only single object of this class (Yes only single object) get create and all user use it. So the object is global to all user, it’s not someone’s property. 

Let’s have a look of below code.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
using System.Data.SqlClient;
using System.Data;
using System.Diagnostics;
 
namespace BlogProject
{
    //Singletone Design patern in C#
    public class SingleTone
    {
        private SingleTone()
        {
        }
        private static SingleTone Single;
        public Int32 Pagecount{get;set;}
 
        public static SingleTone ReturnObject()
        {
            if (Single != null)
            {
                return Single;
            }
            else
            {
                Single = new SingleTone();
                return Single;
            }
 
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            SingleTone s = SingleTone.ReturnObject();
            s.Pagecount = 100;
 
            SingleTone s1 = SingleTone.ReturnObject();
            s1.Pagecount = 200;
 
            Console.WriteLine(s.Pagecount);
            Console.ReadLine();
        }
    }
 
}


Prototype Design pattern

Prototype design pattern is used to make copy of any object. Now question may come in your mind, what we will do by making a copy of one object? Let me explain one scenario where prototype pattern comes in play.

You want to send invitation request to all your friend in your birthday and I am assuming that all your friends stays near to your house, not much far. And as all are near to your house there address will be very similar or slightly different to each other. Now I am assuming in address you will mention

Country, State, City, PIN etc.

And those will be same for all of your friend. Now if you make one primary copy and copy all other from primary one then your task will reduce by 70%. Yes, I know you will tell me what about friend name. Yes only that attribute you have to set for each and every object, That’s why I said 70% otherwise I would say 100 %  J .

Here is the hero for Prototype pattern implementation.

public Location Clone(Location
objLoc)
 {
            return (Location)objLoc.MemberwiseClone();
        }
 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
using System.Data.SqlClient;
using System.Data;
using System.Diagnostics;
 
namespace BlogProject
{
    // Prototype Design patern in C#
    class Location
    {
        public string CountryName { get; set; }
        public string StateName { get; set; }
        public String DistrictName { get; set; }
        public string RepecientName { get; set; }
 
        public Location Clone(Location objLoc)
        {
            return (Location)objLoc.MemberwiseClone();
        }
 
    }
 
 
    class Program
    {
        static void Main(string[] args)
        {
 
            Location L1 = new Location();
            L1.CountryName = "India";
            L1.StateName = "West Bengal";
            L1.DistrictName = "Howrah";
            L1.RepecientName = "Sourav Kayal";
 
            Location L2 = new Location();
 
            L2 = L1.Clone(L1);
            L2.RepecientName = "Prasanta Kumar Kayal";
 
            Console.WriteLine("Country Name:- "+ L2.CountryName +"\n");
            Console.WriteLine("State Name:- " + L2.StateName + "\n");
            Console.WriteLine("District Name:- " + L2.DistrictName + "\n");
            Console.WriteLine("Recipient Name:- " + L2.RepecientName + "\n");
            Console.ReadLine();
        }
    }
}

 

Conclusion
Hope this article helps understand and get fundamental idea of design pattern. Proper design pattern has to be implemented after careful consideration. 


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About the Author

Sourav.Kayal
Full Name: Sourav Kayal
Member Level: Silver
Member Status: Member,MVP
Member Since: 6/20/2013 2:09:01 AM
Country: India
Read my blog here http://ctrlcvprogrammer.blogspot.in/
http://www.dotnetfunda.com
I am .NET developer working for HelixDNA Technologies,Bangalore in healthcare domain. Like to learn new technology and programming language. Currently working in ASP.NET ,C# and other microsoft technologies.

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