An `enum`, short for enumeration, is a user-defined data type consisting of a set of named constants. Each constant represents a distinct value, typically integers, but in some languages, they can also be associated with other data. `enums` provide a way to define a collection of related values within a specific domain, offering improved code readability, maintainability, and type safety by preventing the use of arbitrary values. They help avoid 'magic numbers' by representing values with descriptive names.
Enum meaning with examples
- In Python, you can create an enum using the `enum` module. For instance, a `Color` enum might include `RED`, `GREEN`, and `BLUE`. This helps when building a function which accepts colours, avoiding confusion with different integer codes and making code easier to read. It also means you can restrict to only valid values and avoid typos like REDD where RED is intended.
- In C#, `enums` are strongly typed, meaning you can't accidentally assign a value of an incorrect type to an `enum` variable. For example, an `OrderStatus` enum (PENDING, SHIPPED, DELIVERED) ensures that a variable representing an order's state only contains the possible `OrderStatus` values, helping to avoid logic errors related to invalid states in a system.
- Java also uses `enums` to define sets of constants. `enums` can also have methods, constructors, and fields, just like a normal class, providing advanced functionalities. Defining a `Direction` enum (NORTH, SOUTH, EAST, WEST) can be coupled with methods to check if a move is valid according to the specific rules of a program.
- JavaScript uses `enums` too, by using libraries to provide the features. For example, the `enum` library provides a way to define a `DayOfWeek` enum (MONDAY, TUESDAY, etc.). This is beneficial in a web application where you need to differentiate between weekdays, limiting values and enhancing the program’s robustness, particularly when validating user inputs or filtering data.
- Swift uses `enums` to define sets of related values, and can be more powerful than many other languages. A `Suit` enum (CLUBS, DIAMONDS, HEARTS, SPADES) could be coupled with functions which provide a card's colour, or a rank. This enables comprehensive type checking, offering features, like the ability to associate values of different types to each case.