Design Patterns Part 1

Singleton Pattern

The Singleton pattern is a design pattern that restricts the instantiation of a class to a single instance, which can be useful in scenarios like logging. However, it faces criticism for being difficult to test due to its self-managed lifecycle and persistence. Michael Outlaw and Joe Zack discuss the challenges of testing singletons, particularly when unit tests modify the singleton's state, requiring careful state management 1. Outlaw highlights the flexibility of the double-check locking mechanism, which allows for reinitialization and self-healing, reducing testing difficulties 2.

The biggest problem I have is testing.

--- Joe Zack

Despite its drawbacks, the Singleton pattern remains popular for certain use cases, though it is often seen as a facade for global variables 2.

   

Factory Patterns

Factory patterns are essential in object-oriented design for creating objects without specifying the exact class of object that will be created. Joe Zack explains that factory methods involve multiple factories, each responsible for creating different types of objects, such as various maze games 3. This pattern uses reflection to instantiate the appropriate factory based on configuration or input values, allowing for flexible object creation without direct instantiation 3.

If you are confused right now, then it just means you're understanding, because this is confusing.

--- Joe Zack

The Factory Method Pattern is a variation that emphasizes creating objects through a common interface, enhancing code maintainability and scalability 4.

   

Builder Patterns

Builder patterns are used to construct complex objects step by step, allowing client code to dictate the construction process. Joe Zack contrasts builders with factories, noting that builders require the calling code to assemble the object, as seen in examples like the StringBuilder and UriBuilder in .NET 5. These patterns are particularly useful when the final object requires a series of method calls to configure its state 5.

It's a great way to build a complex object.

--- Joe Zack

Michael Outlaw praises the builder pattern for its elegance and flexibility, despite its verbosity, as it allows for precise control over the object's construction 6.

   

Prototype Pattern

The Prototype pattern involves creating new objects by cloning existing ones at runtime, a concept integral to languages like JavaScript. Joe Zack describes how this pattern allows for dynamic object creation, enabling features like game mods where new object types can be introduced without altering existing code 7. This pattern's strength lies in its ability to clone objects whose types are unknown at compile time, facilitating runtime flexibility 8.

You can shoot anything that knows how to clone itself.

--- Joe Zack

Alan Underwood notes that the Prototype pattern is particularly useful in scenarios where object creation needs to be adaptable and extendable, such as in gaming environments 8.