Abstract Factory, Factory Method, Builder

Question

It may seem as if this is question is a dupe, but please bear with me - I promise I\'ve read the related posts (and the GOF book).

After everything I\'ve read, I still

Answer 1

Builder

// Builder encapsulates construction of other object. Building of the object can be done in multiple steps (methods)
public class ConfigurationBuilder
{
  // Each method adds some configuration part to internally created Configuration object
  void AddDbConfiguration(...);
  void AddSmtpConfiguration(...);
  void AddWebServicesConfiguration(...);
  void AddWebServerConfiguration(...);

  // Returns built configuration
  Configuration GetConfiguration();
}

Factory method

// Factory method is declared in base class or interface. Subclass defines what type is created by factory method.
public interface ICacheProvider
{
  ISession CreateCache(); // Don't have to return new instance each time - such decission is part of implementation in derived class.
}

public class InMemoryCacheProvider : ICacheProvider
{ ... }

public class DbStoredCacheProvider : ICacheProvider
{ ... }

// Client code
ICacheProvider provider = new InMemoryCacheProvider
ICache cache = provider.CreateCache(); 

Abstract Factory

// Abstract factory defines families of platform classes - you don't need to specify each platform class on the client.
public interface IDbPlatform
{
  // It basically defines many factory methods for related classes
  IDbConnection CreateConnection();
  IDbCommand CreateCommand();
  ...
}

// Abstract factory implementation - single class defines whole platform
public class OraclePlatfrom : IDbPlatform
{ ... }

public class MySqlPlatform : IDbPlatform
{ ... }

// Client code:
IDbPlatform platform = new OraclePlatform();
IConnection connection = platform.CreateConnection(); // Automatically Oracle related
...