using System;

/*

Problem without Factory pattern?

-Initially a object is created with the "new" operator. The basic mechanism of object creation could result in design problem or added complexity to the design.

-On each object creation we must use the new keyword. The Factory helps you to reduce this practice and use the common interface to create an object.

​

What is Factory?

Ans-The Factory is a creational pattern that simplifies object creations. You no need to worry about object creation just need to supply an appriorate parameter and factory will provide you

    a appropriate product as needed.

    * Creating object without exposing the instantiation logic to the client

    * Referring to the newly created objects through a common interface

    To implement factory pattern we just need one class which may or may not static and interface to give reference of that factory.

    Factory means we have to provide centeral location to create objects.

    It decouples concrete classes from its client.

*/

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Factory Design pattern");

        Teacher objTeacher= new Teacher();

        Console.WriteLine(objTeacher.getName());

        Console.WriteLine(objTeacher.getAge());

        Student objStudent= new Student();

        Console.WriteLine(objStudent.getName());

        Console.WriteLine(objStudent.getAge());

        //So in above example we ended up in client with creating new objects and client know all about conceret classes like for which we are creating object.

        //To resolve this issue we need to use Factory pattern.

        IPerson ob= ObjectFactory.CreateObject("teacher1");

        Console.WriteLine(ob.getName());

        Console.WriteLine(ob.getAge());

        IPerson ob1= ObjectFactory.CreateObject("student1");

        Console.WriteLine(ob1.getName());

        Console.WriteLine(ob1.getAge());

        //Now tomorrow if any new type will come we just need to change a single location which is inside ObjectFacoty class not every client.

    }

}

​

public class Teacher

{

    public string getName()

    {

        return "Teacher Name";

    }

    public int getAge()

    {

        return 30;

    }

}

​

public class Student

{

    public string getName()

    {

        return "Student Name";

    }

    public int getAge()

    {

        return 22;

    }

}

//Factory pattern 

public interface IPerson

{

    string getName();

    int getAge();

}

​

public class  ObjectFactory

{

    public static IPerson CreateObject(string typeofObject)

    {

          IPerson obj= null;

          if (typeofObject.ToLower() == "teacher1")

           {

              obj= new Teacher1();

           }

         else

           {

                obj= new Student1();

            }

        return obj;

    }

} 

public class Teacher1 : IPerson

{

    public string getName()

    {

        return "Teacher Name1";

    }

    public int getAge()

    {

        return 31;

    }

}

​

public class Student1 : IPerson

{

    public string getName()

    {

        return "Student Name1";

    }

    public int getAge()

    {

        return 23;

    }

}