Immutable Collections
Explore how to protect data integrity using immutable collections in C#. Understand why IReadOnlyList<T> does not guarantee true immutability and how System.Collections.Immutable provides collections that prevent modification. Learn about non-destructive mutation methods to safely add or update data, enhancing thread safety and predictable application behavior.
In software development, protecting data from unintended modifications is critical for building reliable, bug-free applications. While C# provides features to restrict how standard collections are accessed, these tools do not completely freeze the underlying data. To achieve absolute certainty that a dataset remains constant across multiple threads or method calls, we must explore true immutability.
The limitation of read-only interfaces
In a previous lesson, we used the IReadOnlyList<T> interface to expose a collection safely. This interface prevents external callers from using methods like Add() or Remove(). However, IReadOnlyList<T> is simply a restrictive wrapper around a mutable collection. It does not make the underlying data truly unchangeable.
If a method retains a reference to the original List<T>, it can still modify the data. The read-only view will immediately reflect those ...