Builder

Intent

Builder is a creational pattern providing you a construction code to produce different types and representations of an object.

Structure

A Builder interface describes the construction pieces common to all types of builders. A concrete implementation of that interface provides the shapes and faces relative for that builder. A Director knows how to use the pieces and assemble the representation for the given object.

The participants are (Gamma, Helm, Johnson and Vlissidies, 1994, p. 99):

Builder

Specifies an abstract interface for the creating parts of a Product object.

ConcreteBuilder

Knows how to build individual pieces by implementing the Builder interface.

Director

Constructs an object using the Builder interface.

Product

The complex object that is represented with the Builder interface. The product knows its internal representation and includes classes that define the constituent parts, including interfaces for assembling parts to the final result.