10.10 Summary

Rust enums offer a type-safe, powerful way to define types with multiple variants, optionally holding data, significantly improving on C’s enum and union.

Key takeaways:

  • Unified Concept: Combines enumeration and data association safely.
  • Type Safety: Distinct types, preventing misuse common in C.
  • Namespacing: Variants are typically qualified (Enum::Variant) but can be used unqualified via use.
  • Pattern Matching: match and if let provide exhaustive, ergonomic handling.
  • Data Association: Variants hold diverse data structures.
  • Iteration/Sequencing: Not built-in for basic enums, but implementable via constants or methods.
  • Memory Efficiency: Sized to largest variant; Box can optimize.
  • Foundation: Core types like Option and Result are enums.
  • Alternative to Inheritance: Models fixed sets of related types with static dispatch.

Mastering enums and pattern matching is crucial for idiomatic Rust, enabling clear, robust, and safe code. They are central to Rust’s design for correctness and expressiveness.