Design Pattern: Abstract Factory

Abstract Factory

Type: Object Creational

Intent: Provide an interface for creating families of related or dependent objects without specifying their concrete classes.  This will give you the ability to have diverse implementations for a common interface.

Rough Description: Abstract Factory is the interface that you define to encapsulate all the objects of a certain family.  From there you can create what are called "Concrete Factory", which actually instantiates the family of objects for you.  Your client or consumer will only know of the interface.  Somewhere in your code, you will set the interface to your Concrete Factory which will do the heavy lifting of instantiating your objects.

Applicability
  • A system should be independent of how its products should be created, composed, or represented.
  • A system should be configured with one of multiple families of products.
  • A family of related products need to be configured together, and relations enforced.
  • You want to provide a class of product, but don't want to reveal their implementations.
Participants
  • Abstract Factory - Interface for construction operations
  • Concrete Factory - Implements the operations for creating concrete objects
  • Abstract Product - Interface for declaring the properties of an object
  • Concrete Product - Implements the objects that will be created
  • Client - Only uses the interfaces defined by Abstract Factory and Abstract Product classes
Collaborations
  • Normally a single instance of Concrete Factory is created at run-time.
  • Abstract Factory defers product creation to its Concrete Factory Sub-classes.
Consequences
  1. Isolates concrete classes - Enables you to control what objects your applications creates.  Decouples the object's names from your client code. [ + ]
  2. It makes exchanging product families easier - Because your code does not explicitly say what is being created, you can swap out the Concrete Factory and create your new family. [ + ]
  3. Promotes consistency between products - Makes sure that as you create families of objects, there is a parity between families. [ + ]
  4. Supporting new kinds of families becomes more difficult - If you need to add support for some new objects in one family, you will need to implement this in all sub classes of your factory interface. [ - ]

Comments

Post a Comment

Popular posts from this blog

Uncle Bob's Clean Architecture

Image
The basis of my current understanding of architecture comes from the brilliant mind of Robert C. Martin (Uncle Bob). You can find the original post through his blog , which I strongly encourage you to read. In this post I'll try to summarize some of the key points I've understood from his post. Clean Architecture Source Clean architecture is a design used to emphasize the structure and relation of your various code components to promote the idea of Dependency Rule , such that "source code dependencies only point inwards" . Clean architecture is able to promote this by defining that your software system consists of various layers , that can be organized in such a way that the layers point in one direction, and a dependency graph will not have circular reference. The reason this is important is because it allows you to keep closely code related, and increase clarity of how components fit into your system. Explaining the Layers We can really separate out this
Read more

C4 Model: Describing Software Architecture

Image
The point behind a presentation of Visualizing Software Architecture , by Simon Brown, was that we need to standardize the way software developers communicate with each other in respect to our discussions of software architecture. As part of Simon's consultation, one exercise he gave to software architects was a simple task to white board the architecture of a software system. The results he received varied immensely, and there was never a defacto standard format that he received from this exercise. When inspecting the feedback from the participants, the general answer was that it was easy to come up with the design, but difficult to properly put their ideas onto paper, or white board in this case. White Board Example, c4model.com Simon sought to start a movement by defining a set of organizational rules to help us describe our software architecture with a set of standard terminologies. His work has let to C4 Model , which stands for C ontext, C ontainers, C omponents,
Read more

Running RabbitMQ with Docker

Image
Short post today, mostly just wanted to how to setup RabbitMQ for local development. Refer back to my previous post to learn more about RabbitMQ. Prerequisite Docker For complete guide reference, check out the Docker Hub Website for RabbitMQ . Why use Docker? Before starting my current job at iHerb, I would go straight for the Windows installation (my development environment) for all of my development tools needs. It was straight forward and "just worked" a lot of the time. What I've begun to realize experimenting with all these different tooling and services is that things can get a bit cluttered, you will have a bunch of supporting systems that need to be run - caches, queues, databases and it can be a hassle to manage them through window services and executables. Additionally some of these require additional dependencies outside of the executable itself, which prompts you to install even more tooling. The great thing about docker is that it defi
Read more