Facade en C#
Facade es un patrón de diseño estructural que proporciona una interfaz simplificada (pero limitada) a un sistema complejo de clases, bibliotecas o _frameworks_.
El patrón Facade disminuye la complejidad general de la aplicación, al mismo tiempo que ayuda a mover dependencias no deseadas a un solo lugar.
Complejidad:
Popularidad:
Ejemplos de uso: El patrón Facade se utiliza habitualmente en aplicaciones escritas en C#. Es de especial utilidad al trabajar con bibliotecas y API complejas.
Identificación: El patrón Facade se puede reconocer en una clase con una interfaz simple, pero que delega la mayor parte del trabajo a otras clases. Normalmente, las fachadas gestionan todo el ciclo de vida de los objetos que utilizan.
Ejemplo conceptual
Este ejemplo ilustra la estructura del patrón de diseño Facade. Se centra en responder las siguientes preguntas:
- ¿De qué clases se compone?
- ¿Qué papeles juegan esas clases?
- ¿De qué forma se relacionan los elementos del patrón?
Program.cs: Ejemplo conceptual
using System;
namespace RefactoringGuru.DesignPatterns.Facade.Conceptual
{
// The Facade class provides a simple interface to the complex logic of one
// or several subsystems. The Facade delegates the client requests to the
// appropriate objects within the subsystem. The Facade is also responsible
// for managing their lifecycle. All of this shields the client from the
// undesired complexity of the subsystem.
public class Facade
{
protected Subsystem1 _subsystem1;
protected Subsystem2 _subsystem2;
public Facade(Subsystem1 subsystem1, Subsystem2 subsystem2)
{
this._subsystem1 = subsystem1;
this._subsystem2 = subsystem2;
}
// The Facade's methods are convenient shortcuts to the sophisticated
// functionality of the subsystems. However, clients get only to a
// fraction of a subsystem's capabilities.
public string Operation()
{
string result = "Facade initializes subsystems:\n";
result += this._subsystem1.operation1();
result += this._subsystem2.operation1();
result += "Facade orders subsystems to perform the action:\n";
result += this._subsystem1.operationN();
result += this._subsystem2.operationZ();
return result;
}
}
// The Subsystem can accept requests either from the facade or client
// directly. In any case, to the Subsystem, the Facade is yet another
// client, and it's not a part of the Subsystem.
public class Subsystem1
{
public string operation1()
{
return "Subsystem1: Ready!\n";
}
public string operationN()
{
return "Subsystem1: Go!\n";
}
}
// Some facades can work with multiple subsystems at the same time.
public class Subsystem2
{
public string operation1()
{
return "Subsystem2: Get ready!\n";
}
public string operationZ()
{
return "Subsystem2: Fire!\n";
}
}
class Client
{
// The client code works with complex subsystems through a simple
// interface provided by the Facade. When a facade manages the lifecycle
// of the subsystem, the client might not even know about the existence
// of the subsystem. This approach lets you keep the complexity under
// control.
public static void ClientCode(Facade facade)
{
Console.Write(facade.Operation());
}
}
class Program
{
static void Main(string[] args)
{
// The client code may have some of the subsystem's objects already
// created. In this case, it might be worthwhile to initialize the
// Facade with these objects instead of letting the Facade create
// new instances.
Subsystem1 subsystem1 = new Subsystem1();
Subsystem2 subsystem2 = new Subsystem2();
Facade facade = new Facade(subsystem1, subsystem2);
Client.ClientCode(facade);
}
}
}
Output.txt: Resultado de la ejecución
Facade initializes subsystems:
Subsystem1: Ready!
Subsystem2: Get ready!
Facade orders subsystems to perform the action:
Subsystem1: Go!
Subsystem2: Fire!
