C# implementation of Builder pattern

The builder pattern Separates the construction of a complex object from its representation.

The players in this pattern are:
1. Product (Room)
Represents the complex object which includes many classes(parts)
2. Builder (RoomBuilder)
Specifies an abstract class or an interface for creating parts of a Product object
3. ConcreteBuilder (WoodBuilder, GlassBuilder)

• Constructs parts of the product by implementing the Builder class/interface

• provides a way for retrieving the product

4. Director (House)
Constructs an object (room) using the Builder class/interface

So, you use the Builder pattern when:

• the object to be constructed has many parts and might have different representations.

• you need control over the construction process.

//The library code
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace BuilderPattern
{
// The 'Product' class
public class Room
{
string _type;
List _parts = new List<string>();
public Room(string type)
{
_type = type;
}
public void Add(string part)
{
_parts.Add(part);
}
public void Show()
{
Console.WriteLine("\nProduct Parts:");
foreach (string part in _parts)
Console.Write(part+"\t");
Console.WriteLine();
}
}

// The 'Builder' abstract class
public abstract class RoomBuilder
{
protected Room room;
public Room Room
{
get { return room; }
}
public abstract void BuildDoor();
public abstract void BuildWindow();
}

// The 'ConcreteBuilder 1' class
public class WoodBuilder : RoomBuilder
{
public WoodBuilder()
{
room = new Room("WoodRoom");
}
public override void BuildDoor()
{
room.Add("Wood-Door");
}
public override void BuildWindow()
{
room.Add("Wood-Window");
}
}

// The 'ConcreteBuilder 2' class
public class GlassBuilder : RoomBuilder
{
public GlassBuilder()
{
room = new Room("GlassRoom");
}
public override void BuildDoor()
{
room.Add("Glass-Door");
}
public override void BuildWindow()
{
room.Add("Glass-Window");
}
}

// The 'Director' class
public class House
{
public void Construct(RoomBuilder roomBuilder) // you may label it as 'static'
{
roomBuilder.BuildDoor();
roomBuilder.BuildWindow();
roomBuilder.BuildWindow();
/* You can provide Additional Director
* with another series of steps
* like adding tow doors..*/
}
}
}