Builder Design Pattern

Separate the construction of a complex object from its representation so that the same construction process can create different representations.

using System;
using System.Collections.Generic;

namespace Patterns
{
/// <summary>
/// MainApp startup class for .NET optimized
/// Builder Design Pattern.
/// </summary>
public class MainApp
{
public static void Main()
{
VehicleBuilder builder;

// Create shop with vehicle builders
Shop shop = new Shop();

// Create builders and display vehicle
builder = new ScooterBuilder();
shop.Construct(builder);
builder.Vehicle.Show();

builder = new CarBuilder();
shop.Construct(builder);
builder.Vehicle.Show();

builder = new MotorCycleBuilder();
shop.Construct(builder);
builder.Vehicle.Show();

// Wait for user
Console.ReadKey();
}
}

/// <summary>
/// The 'Director' class
/// </summary>
class Shop
{
// Builder uses a complex series of steps
public void Construct(VehicleBuilder vehicleBuilder)
{
vehicleBuilder.BuildFrame();
vehicleBuilder.BuildEngine();
vehicleBuilder.BuildWheels();
vehicleBuilder.BuildDoors();
}
}

/// <summary>
/// The 'Builder' abstract class
/// </summary>
abstract class VehicleBuilder
{
protected Vehicle vehicle;

// Constructor
public VehicleBuilder(VehicleType vehicleType)
{
vehicle = new Vehicle(vehicleType);
}

// Property
public Vehicle Vehicle
{
get { return vehicle; }
}

public abstract void BuildFrame();
public abstract void BuildEngine();
public abstract void BuildWheels();
public abstract void BuildDoors();
}

/// <summary>
/// The 'ConcreteBuilder1' class
/// </summary>
class MotorCycleBuilder : VehicleBuilder
{
// Invoke base class constructor
public MotorCycleBuilder()
: base(VehicleType.MotorCycle)
{
}

public override void BuildFrame()
{
vehicle[PartType.Frame] = "MotorCycle Frame";
}

public override void BuildEngine()
{
vehicle[PartType.Engine] = "500 cc";
}

public override void BuildWheels()
{
vehicle[PartType.Wheel] = "2";
}

public override void BuildDoors()
{
vehicle[PartType.Door] = "0";
}
}

/// <summary>
/// The 'ConcreteBuilder2' class
/// </summary>
class CarBuilder : VehicleBuilder
{
// Invoke base class constructor
public CarBuilder()
: base(VehicleType.Car)
{
}

public override void BuildFrame()
{
vehicle[PartType.Frame] = "Car Frame";
}

public override void BuildEngine()
{
vehicle[PartType.Engine] = "2500 cc";
}

public override void BuildWheels()
{
vehicle[PartType.Wheel] = "4";
}

public override void BuildDoors()
{
vehicle[PartType.Door] = "4";
}
}

/// <summary>
/// The 'ConcreteBuilder3' class
/// </summary>
class ScooterBuilder : VehicleBuilder
{
// Invoke base class constructor
public ScooterBuilder()
: base(VehicleType.Scooter)
{
}

public override void BuildFrame()
{
vehicle[PartType.Frame] = "Scooter Frame";
}

public override void BuildEngine()
{
vehicle[PartType.Engine] = "50 cc";
}

public override void BuildWheels()
{
vehicle[PartType.Wheel] = "2";
}

public override void BuildDoors()
{
vehicle[PartType.Door] = "0";
}
}

/// <summary>
/// The 'Product' class
/// </summary>
class Vehicle
{
private VehicleType _vehicleType;

private Dictionary<PartType, string> _parts =
new Dictionary<PartType, string>();

// Constructor
public Vehicle(VehicleType vehicleType)
{
this._vehicleType = vehicleType;
}

// Indexer
public string this[PartType key]
{
get { return _parts[key]; }
set { _parts[key] = value; }
}

public void Show()
{
Console.WriteLine("\n---------------------------");
Console.WriteLine("Vehicle Type: {0}", _vehicleType);
Console.WriteLine(" Frame : {0}",
this[PartType.Frame]);
Console.WriteLine(" Engine : {0}",
this[PartType.Engine]);
Console.WriteLine(" #Wheels: {0}",
this[PartType.Wheel]);
Console.WriteLine(" #Doors : {0}",
this[PartType.Door]);
}
}

/// <summary>
/// Part type enumeration
/// </summary>
public enum PartType
{
Frame,
Engine,
Wheel,
Door
}

/// <summary>
/// Vehicle type enumeration
/// </summary>
public enum VehicleType
{
Car,
Scooter,
MotorCycle
}
}