Factory method

Static diagram :

Description :

Type :

Cr (Creational)

Intent :

Define an interface for creating an object, but let subclasses decide which class to instantiate. Factory Method lets a class defer instantiation to subclasses.

Applicability :

Use the Factory Method pattern when :
- a class can't anticipate the class of objects it must create.
- a class wants its subclasses to specify the objects it creates.
- classes delegate responsibility to one of several helper subclasses, and you want to localize the knowledge of which helper subclass is the delegate.

Pattern's participants :

Product
Defines the interface of objects the factory method creates.
ConcreteProduct
Implements the Product interface.
Creator
Declares the factory method, which returns an object of type Product. Creator may also define a default implementation of the factory method that returns a default ConcreteProduct object.
May call the factory method to create a Product object.
ConcreteCreator
Overrides the factory method to return an instance of a ConcreteProduct.

Problems :

1. Délégation de la création

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Design patterns

Factory method

Static diagram :

Description :

Pattern's participants :

Problems :