Builder Pattern
Description:
» The Builder pattern separates the specification of a complex object from its actual construction;» The Builder pattern is based on Directors and Builders. Any number of Builder classes can be called by a director to produce a product according to specification;
» A specific advantage of the Builder/Director partnership is that the products do not all necessarily turn out the same. The Builder can redefine the way it works and, even with the same Director, produce a different product;
» Only when the construction is complete is the product returned to the director for the director to work with.
Use When:
» The algorithm for creating parts is independent from the parts themselves;» The object to be assembled might have different representations;
» You need fine control over the construction process.
//Define the IProductBuilder interface to be used as the "blueprint" for the main Builder classes.
public interface IProductBuilder
{
ProductFactory Product { get; }
void BuildFrame();
void BuildEngine();
void BuildWheels();
void BuildDoors();
}
//The MotorCycleBuilder class (object) represents a Builder class.
public class MotorCycleBuilder : IProductBuilder
{
public MotorCycleBuilder()
{
Product = new ProductFactory("MotorCycle");
}
public ProductFactory Product { get; private set; }
public void BuildFrame()
{
Product["frame"] = "MotorCycle Frame";
}
public void BuildEngine()
{
Product["engine"] = "500 cc";
}
public void BuildWheels()
{
Product["wheels"] = "2";
}
public void BuildDoors()
{
Product["doors"] = "0";
}
}
//The VehicleBuilder class (object) represents a Builder class.
public class VehicleBuilder : IProductBuilder
{
public VehicleBuilder()
{
Product = new ProductFactory("Vehicle");
}
public ProductFactory Product { get; private set; }
public void BuildFrame()
{
Product["frame"] = "Vehicle Frame";
}
public void BuildEngine()
{
Product["engine"] = "2500 cc";
}
public void BuildWheels()
{
Product["wheels"] = "4";
}
public void BuildDoors()
{
Product["doors"] = "4";
}
}
//The ScooterBuilder class (object) represents a Builder class.
public class ScooterBuilder : IProductBuilder
{
public ScooterBuilder()
{
Product = new ProductFactory("Scooter");
}
public ProductFactory Product { get; private set; }
public void BuildFrame()
{
Product["frame"] = "Scooter Frame";
}
public void BuildEngine()
{
Product["engine"] = "50 cc";
}
public void BuildWheels()
{
Product["wheels"] = "2";
}
public void BuildDoors()
{
Product["doors"] = "0";
}
}
public interface IProductBuilder
{
ProductFactory Product { get; }
void BuildFrame();
void BuildEngine();
void BuildWheels();
void BuildDoors();
}
//The MotorCycleBuilder class (object) represents a Builder class.
public class MotorCycleBuilder : IProductBuilder
{
public MotorCycleBuilder()
{
Product = new ProductFactory("MotorCycle");
}
public ProductFactory Product { get; private set; }
public void BuildFrame()
{
Product["frame"] = "MotorCycle Frame";
}
public void BuildEngine()
{
Product["engine"] = "500 cc";
}
public void BuildWheels()
{
Product["wheels"] = "2";
}
public void BuildDoors()
{
Product["doors"] = "0";
}
}
//The VehicleBuilder class (object) represents a Builder class.
public class VehicleBuilder : IProductBuilder
{
public VehicleBuilder()
{
Product = new ProductFactory("Vehicle");
}
public ProductFactory Product { get; private set; }
public void BuildFrame()
{
Product["frame"] = "Vehicle Frame";
}
public void BuildEngine()
{
Product["engine"] = "2500 cc";
}
public void BuildWheels()
{
Product["wheels"] = "4";
}
public void BuildDoors()
{
Product["doors"] = "4";
}
}
//The ScooterBuilder class (object) represents a Builder class.
public class ScooterBuilder : IProductBuilder
{
public ScooterBuilder()
{
Product = new ProductFactory("Scooter");
}
public ProductFactory Product { get; private set; }
public void BuildFrame()
{
Product["frame"] = "Scooter Frame";
}
public void BuildEngine()
{
Product["engine"] = "50 cc";
}
public void BuildWheels()
{
Product["wheels"] = "2";
}
public void BuildDoors()
{
Product["doors"] = "0";
}
}
//The DirectorFactory class (object) represents a Director class.
public class DirectorFactory
{
public void Construct(IProductBuilder builder)
{
builder.BuildFrame();
builder.BuildEngine();
builder.BuildWheels();
builder.BuildDoors();
}
}
public class DirectorFactory
{
public void Construct(IProductBuilder builder)
{
builder.BuildFrame();
builder.BuildEngine();
builder.BuildWheels();
builder.BuildDoors();
}
}