One Pager Cheat Sheet

• In software development, the concepts of mutability and immutability, essential to both object-oriented and functional programming, refer to an object's ability to change its internal state, impacting the robustness, efficiency, and clarity of the code.
• The article describes the differences between mutable and immutable objects in programming, with mutable objects being changeable after initialization and offering flexibility and memory-efficiency, but issues with thread safety and predictability, and immutable objects being unchangeable after creation providing thread safety, predictability, readability, and security, but can lead to memory overhead; strings are given as an example of immutable objects.
• Immutable objects are defined as those whose state cannot be modified after creation, any changes seeming to alter the state actually creates a new object, with the original remaining unchanged, providing benefits in situations that need predictability, readability, thread safety, and security. This trait distinguishes them from mutable objects, which can have their state changed post-creation.
• Programmers may prefer mutable objects for their speed & efficiency, convenience and in cases of necessity, like user input or UI modifications, but despite such benefits, mutable objects can lead to higher risk of bugs, making them less suitable except in instances requiring maximum speed or for small simple programs.
• The advantages of immutability in programming include improved readability, long-term speed and efficiency, easier traceability, better safety and validity, and ideal caching capabilities due to values of immutable objects being unchangeable without the developer's knowledge.
• The image illustrates the concepts of immutability and mutability in programming, with functional programming favoring immutability for reduced bugs and easier reasoning, and imperative programming utilizing mutability for potentially better performance and more natural modeling.
• The statement is false as mutability can often result in complex and error-prone code with unexpected side effects, especially in large codebases or among multiple developers, whereas immutability enhances readability and predictability as variables maintain their values, making the code more understandable, manageable, and less prone to bugs.
• In Python, mutable data types such as list, dict, set, byte array, and user-defined classes can be modified after their creation, as demonstrated by adding a new favorite movie to a list, while immutable data types like str, int, float, complex, tuple, frozen set, boolean cannot, resulting in a TypeError when trying to change part of a string.
• In Java, mutable data types such as Array, ArrayList, HashMap, and java.util.Date allow their values to be changed, while immutable data types like String, Integer, Long, and java.math.BigInteger do not; although some mutable classes can be converted to immutable using methods or libraries like Guava or Apache Commons Lang.
• The image provides a comparison between mutable and immutable data types in Python, Java, and JavaScript, highlighting differences such as lists and dictionaries (Python), arrays and hashmaps (Java), and objects and arrays (JavaScript) being mutable, while strings and tuples (Python), strings and primitives (Java), and strings and numbers (JavaScript) are immutable.
• In both Java and Python, strings are immutable, meaning they cannot be changed once created, differing from mutable data structures like lists or arrays; this feature enhances security by ensuring string content cannot be altered unintentionally.
• In JavaScript, mutable data types like Object and Array can be altered, as demonstrated by changing an element in an array, while immutable data types such as String, Number, Boolean, undefined, and null cannot be changed, which is shown through the failed attempt to modify a string.
• In C++, mutable container types include Vector, Map, Set, Deque, Array, and List, which can have their values altered, while immutability is achieved using the const qualifier to prevent any changes to a value.
• The distinction between mutability and immutability in programming languages is crucial for developers and should be chosen based on specific needs: mutable objects may improve performance for performance-intensive tasks, immutability can simplify data handling in concurrency and parallelism, and ensure data integrity and security in sensitive operations.