Builder Design Pattern

Builder pattern separate the construction of a object from its representation so that the same construction process can create different representations.

The Builder Pattern is comprised of four components: a builder interface, a concrete builder, a director and a product.

Builder is an interface which is used to define all the steps to create a product.

   //This is the Builder Interface  
   public interface IBlogBuilder  
   {  
     void BuildSendEmail();  
     void BuildShare();  
     Blog blog { get; }  
   }  

ConcreteBuilder is a class which implements the Builder interface to create complex product.

 //This is the Post Concrete Builder class  
   public class PostBuilder : IBlogBuilder  
   {  
     Blog post;  
     public PostBuilder()  
     {  
       post = new Blog("New Post 1");  
     }  
     public void BuildSendEmail()  
     {  
       post.SendEmail();  
     }  
     public void BuildShare()  
     {  
       post.Share();  
     }  
   }  
   //This is the Page Concrete Builder class  
   public class PageBuilder : IBlogBuilder  
   {  
     Blog page;  
     public PageBuilder()  
     {  
       page = new Blog("New Page 1");  
     }  
     public void BuildSendEmail()  
     {  
       page.SendEmail();  
     }  
     public void BuildShare()  
     {  
       page.Share();  
     }  
   }  

Product is a class which defines the parts of the complex object which are to be generated by the builder pattern.

 //This is the Product  
   public class Blog  
   {  
     string Title;  
     public Blog(string name)  
     {  
       Title = name;  
     }  
     public void SendEmail()  
     {  
       //TO DO : Send Email Logic  
     }  
     public void Share()  
     {  
       //TO DO : Send Share Logic  
     }  
   }  

Director is a class which is used to construct an object using the Builder interface.

 //This is the Director class  
   public class BuildBlog  
   {  
     public void ConstructBlog(IBlogBuilder blogBuilder)  
     {  
       blogBuilder.BuildSendEmail();  
       blogBuilder.BuildShare();  
     }  
   }  

Now when we look at the client code we can see how clean it is to create any product.

 using System;  
 namespace dotnetfundamentals.BuilderPattern  
 {  
   class Program  
   {  
     static void Main(string[] args)  
     {  
       //This will create instance of Director  
       BuildBlog newPost = new BuildBlog();  
   
       //Initializes Builder class  
       IBlogBuilder blogBuilder = null;  
   
       //This will create New Post  
       blogBuilder = new PostBuilder();  
       newPost.ConstructBlog(blogBuilder);  
   
       //This will create New Page  
       blogBuilder = new PageBuilder();  
       newPost.ConstructBlog(blogBuilder);  
     }  
   }  
 }