This content originally appeared on HackerNoon and was authored by Maximiliano Contieri
Exposing your collections couples your solution
TL;DR: Use immutable collections to prevent unintended side effects.
Problems
- Unpredictable behavior
- Debugging challenges
- Data corruption
- Violation of the Principle of Least Astonishment
- Premature optimization
- Unexpected Mutations
- Concurrency problems
- Compromised thread safety
- Increased coupling
Solutions
- Use immutable collections
- Create immutable classes
- Copy the collection before modification
- Avoid collection getters
- Avoid automatic properties
- Favor information hiding and encapsulation
Context
Aliasing happens when two or more variables refer to the same object.
This can lead to unexpected side effects, especially when one variable modifies the shared object.
You can't change immutable collections after creation helping you prevent accidental aliasing.
Premature optimizators will argue that copying collections is an expensive operation that you should avoid.
This is a special case of Object Aliasing
Sample Code
Wrong
public class MutableExample {
public static void main(String[] args) {
List<Integer> numbers = List.of(1, 2, 3);
List<Integer> otherNumbers = numbers; // Aliasing
otherNumbers.add(4);
System.out.println(numbers); // Output: [1, 2, 3, 4]
}
}
Right
public class ImmutableExample {
public static void main(String[] args) {
List<Integer> numbers = List.of(1, 2, 3);
List<Integer> otherNumbers = List.copyOf(numbers); // Creating a copy
otherNumbers.add(4);
System.out.println(numbers); // Output: [1, 2, 3]
}
}
Detection
- [x] Semi-Automatic
Several static analysis tools can warn you of aliasing abuse.
Tags
- Immutability
Level
- [x] Intermediate
AI Generation
AI code generators might not always create immutable objects by default, especially when working with mutable collections.
You can prompt them to prioritize immutable collections and wrap existing ones to avoid aliasing.
AI Detection
AI tools can analyze code for potential aliasing issues and suggest using immutable collections instead.
Conclusion
You can avoid unintended side effects using immutable collections.
This will make your code more predictable and easier to reason about.
Related Reading
https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xviii
https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxvi
https://hackernoon.com/finding-the-stinky-parts-of-your-code-code-smell-256-mutable-getters
https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxii
https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xiv
More Info
https://hackernoon.com/nude-models-part-ii-getters-sjo3ua2?embedable=true
https://hackernoon.com/coupling-the-one-and-only-software-designing-problem-9z5a321h?embedable=true
:::warning Disclaimer: Code Smells are my opinion.
:::
:::info Credits: Photo by Martino Pietropoli on Unsplash
:::
If an object is immutable, it can be in only one state, and you win big.
Joshua Bloch
https://hackernoon.com/400-thought-provoking-software-engineering-quotes?embedable=true
:::tip This article is part of the CodeSmell Series on HackerNoon: How to Find the Stinky Parts of your Code
:::
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This content originally appeared on HackerNoon and was authored by Maximiliano Contieri
Maximiliano Contieri | Sciencx (2024-08-29T15:58:16+00:00) Code Smell 266 – Collection Aliasing. Retrieved from https://www.scien.cx/2024/08/29/code-smell-266-collection-aliasing/
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