Abstract Factory en TypeScript
Abstract Factory es un patrón de diseño creacional que resuelve el problema de crear familias enteras de productos sin especificar sus clases concretas.
El patrón Abstract Factory define una interfaz para crear todos los productos, pero deja la propia creación de productos para las clases de fábrica concretas. Cada tipo de fábrica se corresponde con cierta variedad de producto.
El código cliente invoca los métodos de creación de un objeto de fábrica en lugar de crear los productos directamente con una llamada al constructor (operador new). Como una fábrica se corresponde con una única variante de producto, todos sus productos serán compatibles.
El código cliente trabaja con fábricas y productos únicamente a través de sus interfaces abstractas. Esto permite al mismo código cliente trabajar con productos diferentes. Simplemente, creas una nueva clase fábrica concreta y la pasas al código cliente.
Si no sabes la diferencia entre los distintos patrones de fábrica y sus conceptos, lee nuestra Comparación de fábricas.
Complejidad:
Popularidad:
Ejemplos de uso: El patrón Abstract Factory es muy común en el código TypeScript. Muchos frameworks y bibliotecas lo utilizan para proporcionar una forma de extender y personalizar sus componentes estándar.
Identificación: El patrón es fácil de reconocer por los métodos, que devuelven un objeto de fábrica. Después, la fábrica se utiliza para crear subcomponentes específicos.
Ejemplo conceptual
Este ejemplo ilustra la estructura del patrón de diseño Abstract Factory, centrándose en responder las siguientes preguntas:
- ¿De qué clases se compone?
- ¿Qué papeles juegan esas clases?
- ¿De qué forma se relacionan los elementos del patrón?
index.ts: Ejemplo conceptual
/**
* The Abstract Factory interface declares a set of methods that return
* different abstract products. These products are called a family and are
* related by a high-level theme or concept. Products of one family are usually
* able to collaborate among themselves. A family of products may have several
* variants, but the products of one variant are incompatible with products of
* another.
*/
interface AbstractFactory {
createProductA(): AbstractProductA;
createProductB(): AbstractProductB;
}
/**
* Concrete Factories produce a family of products that belong to a single
* variant. The factory guarantees that resulting products are compatible. Note
* that signatures of the Concrete Factory's methods return an abstract product,
* while inside the method a concrete product is instantiated.
*/
class ConcreteFactory1 implements AbstractFactory {
public createProductA(): AbstractProductA {
return new ConcreteProductA1();
}
public createProductB(): AbstractProductB {
return new ConcreteProductB1();
}
}
/**
* Each Concrete Factory has a corresponding product variant.
*/
class ConcreteFactory2 implements AbstractFactory {
public createProductA(): AbstractProductA {
return new ConcreteProductA2();
}
public createProductB(): AbstractProductB {
return new ConcreteProductB2();
}
}
/**
* Each distinct product of a product family should have a base interface. All
* variants of the product must implement this interface.
*/
interface AbstractProductA {
usefulFunctionA(): string;
}
/**
* These Concrete Products are created by corresponding Concrete Factories.
*/
class ConcreteProductA1 implements AbstractProductA {
public usefulFunctionA(): string {
return 'The result of the product A1.';
}
}
class ConcreteProductA2 implements AbstractProductA {
public usefulFunctionA(): string {
return 'The result of the product A2.';
}
}
/**
* Here's the the base interface of another product. All products can interact
* with each other, but proper interaction is possible only between products of
* the same concrete variant.
*/
interface AbstractProductB {
/**
* Product B is able to do its own thing...
*/
usefulFunctionB(): string;
/**
* ...but it also can collaborate with the ProductA.
*
* The Abstract Factory makes sure that all products it creates are of the
* same variant and thus, compatible.
*/
anotherUsefulFunctionB(collaborator: AbstractProductA): string;
}
/**
* These Concrete Products are created by corresponding Concrete Factories.
*/
class ConcreteProductB1 implements AbstractProductB {
public usefulFunctionB(): string {
return 'The result of the product B1.';
}
/**
* The variant, Product B1, is only able to work correctly with the variant,
* Product A1. Nevertheless, it accepts any instance of AbstractProductA as
* an argument.
*/
public anotherUsefulFunctionB(collaborator: AbstractProductA): string {
const result = collaborator.usefulFunctionA();
return `The result of the B1 collaborating with the (${result})`;
}
}
class ConcreteProductB2 implements AbstractProductB {
public usefulFunctionB(): string {
return 'The result of the product B2.';
}
/**
* The variant, Product B2, is only able to work correctly with the variant,
* Product A2. Nevertheless, it accepts any instance of AbstractProductA as
* an argument.
*/
public anotherUsefulFunctionB(collaborator: AbstractProductA): string {
const result = collaborator.usefulFunctionA();
return `The result of the B2 collaborating with the (${result})`;
}
}
/**
* The client code works with factories and products only through abstract
* types: AbstractFactory and AbstractProduct. This lets you pass any factory or
* product subclass to the client code without breaking it.
*/
function clientCode(factory: AbstractFactory) {
const productA = factory.createProductA();
const productB = factory.createProductB();
console.log(productB.usefulFunctionB());
console.log(productB.anotherUsefulFunctionB(productA));
}
/**
* The client code can work with any concrete factory class.
*/
console.log('Client: Testing client code with the first factory type...');
clientCode(new ConcreteFactory1());
console.log('');
console.log('Client: Testing the same client code with the second factory type...');
clientCode(new ConcreteFactory2());
Output.txt: Resultado de la ejecución
Client: Testing client code with the first factory type...
The result of the product B1.
The result of the B1 collaborating with the (The result of the product A1.)
Client: Testing the same client code with the second factory type...
The result of the product B2.
The result of the B2 collaborating with the (The result of the product A2.)
