Immutable object is an object whose state cannot be modified after it is created, requiring any changes to be made by creating a new object with the updated state. This approach is commonly used in functional programming and can help prevent unexpected side effects and make code easier to reason about, though it may require more memory allocation.

How to use it in a sentence

• "I'm not sure why the Facebook app is crashing, but I bet it's because some junior dev mutated an immutable object again," grumbled the senior engineer as she rolled her eyes and opened up the debugger.

• The tech lead at the trendy new startup mandated that all code must use immutable objects, proclaiming "mutability is the root of all evil!" to the team's mix of eye rolls and enthusiastic nods.

If you actually want to learn more...

• Immutable Server - Martin Fowler: This article discusses the Immutable Server pattern, where servers are never modified once deployed and are instead replaced with new, updated instances. It highlights how companies like Netflix have used this approach to enable automatic scaling and recovery.

• Object Collaboration Design - Martin Fowler: This collection of articles covers various topics related to object collaboration design, including dependency injection, collection pipelines, and refactoring techniques that can be used in conjunction with immutable objects to create cleaner, more maintainable code.

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