10.1 Understanding Enums
10.1.1 Origin of the Term "Enum"
The term enum is short for enumeration, which refers to the action of listing items one by one. In programming, an enumeration is a data type consisting of a set of named values. These values are called variants and represent all the possible values that a variable of the enumeration type can hold.
10.1.2 Rust's Enums vs. C's Enums and Unions
In C, enums are a way to assign names to integral constants, improving code readability. However, they are essentially integer values under the hood. C also provides unions, which allow different data types to occupy the same memory space, enabling a variable to store different types at different times.
Rust's enums combine the capabilities of both C's enums and unions. They allow you to define a type by enumerating its possible variants, which can be either simple values or complex data structures. This makes Rust's enums a powerful tool for modeling data that can take on several different but related forms.
Using enums instead of plain integer constants has several benefits:
- Type Safety: Enums are distinct types, preventing accidental misuse of integer values that may not represent valid variants.
- Pattern Matching: Enums work seamlessly with Rust's pattern matching, allowing for expressive and safe handling of different cases.
- Data Association: Variants can carry data, enabling you to associate meaningful information with each variant.