Say it like this
- make this immutable to prevent side effects
- keep it immutable for thread safety
- treat it as immutable once initialized
Use it at work
Code review
- Keep this object immutable. Return a new copy instead.
- Mutating state here causes bugs. Make it immutable.
Infrastructure
- We use immutable servers: we replace them, not patch them.
- Docker images should be immutable.
Security
- Audit logs should be immutable.
- Backups are stored in immutable storage.
Don't say this
Immutable is an adjective describing a property, not a verb for an action. Use make immutable or set as immutable.
Practice
Try it
4 quick exercises
1. You are explaining why strings cannot be changed in your code review. Which sounds most natural?
2. To ensure thread safety, we should keep all shared objects _______ and avoid concurrent modifications.
3. Which sentence uses immutable incorrectly?
4. Rewrite this technical explanation using immutable more naturally: 'We do not allow users to change their IDs once they are created in our database.'
Say it out loud
Phrase 1 of 3
"make this immutable to prevent side effects"
We don't save your recording. The word check uses your browser's speech recognition.
More about immutable
Real examples(3)
- in a standup
"We decided to make our configuration objects immutable so they can't be accidentally modified during runtime."
- in a code review
"This data structure should be immutable because multiple threads are accessing it simultaneously."
- in a team meeting
"By keeping user preferences immutable, we reduce the risk of inconsistent state across our microservices."
More mistakes(2)
Handle with care. Often confused with immutability (the noun form). Do not use as a verb. Do not use to mean read-only without specifying context.
- ✕This array is immutable, so we can read and write to it freely.✓This array is immutable, so we can't modify it; we must create a new array for changes.
Immutable means unable to change, not simply protected. You cannot write to an immutable structure.
- ✕Immutable is just another word for read-only.✓Immutable means the object can't be changed after creation; read-only refers to access permissions.
Immutability is about the nature of the object itself, while read-only is about permission restrictions. They are related but distinct concepts.
Other forms(2)
- immutable adjective
"String objects in Java are immutable by design."
- immutability noun
"The immutability of our data structure guarantees consistency across all requests."
Often used with(4)
- immutable object · Used to describe any object whose state cannot change after instantiation
- make immutable · The action of creating or designating something as immutable
- immutable data · Data that cannot be altered once stored or created
- immutable state · A state that remains fixed and cannot be modified
Similar words(3)
- unchangeable · More general; immutable is more specific to programming contexts
- unmodifiable · Nearly identical meaning; more technical than unchangeable
- fixed · Less precise; fixed can mean stationary or determined, not specifically about object state
Opposites(3)
- mutable
- changeable
- modifiable
Questions(5)
- What does immutable mean in software engineering?
- Immutable describes an object or data structure that cannot be changed after it is created. If you need to modify it, you must create a new object with the desired changes instead of altering the original. This is a fundamental principle in many programming paradigms and frameworks.
- Why do developers use immutable objects?
- Immutable objects provide several advantages: they are safer in multi-threaded environments because no locks are needed, they reduce bugs caused by unexpected state changes, they enable better performance through caching and optimization, and they make code easier to reason about and test.
- Is immutable formal or informal?
- Immutable is a formal technical term used in professional software engineering contexts. It appears in technical documentation, code reviews, architecture discussions, and job interviews. While technical, it is the standard term used by all developers regardless of formality level.
- How do I use immutable in a sentence at work?
- Use immutable as an adjective to describe objects or data: We should make this configuration immutable. Or discuss the concept: Immutability improves thread safety. You can also use the noun form immutability: The immutability of strings in Java requires careful memory management.
- What is the difference between immutable and read-only?
- Read-only refers to access permissions; a read-only object can be read but not modified through normal access. Immutable means the object fundamentally cannot change after creation, regardless of permissions. An immutable object is always read-only, but a read-only object is not necessarily immutable.
