21.20 Summary

Patterns are a fundamental and powerful feature woven throughout Rust, offering significantly more capability than C’s switch. Key advantages include:

  • Safety via Exhaustiveness: The compiler enforces that all possibilities are handled, especially for enums, preventing runtime errors from unhandled cases.
  • Expressive Destructuring: Patterns provide a concise syntax for extracting data from tuples, structs, enums, slices, and more.
  • Versatile Matching: Support for literals, ranges, variables, wildcards (_), OR-patterns (|), @-bindings, references (&, ref, ref mut), and conditional guards (if).
  • Clarity through Refutability: The distinction between irrefutable and refutable patterns guides their correct usage in different contexts (let, match, if let, etc.).
  • Wide Applicability: Patterns are used in match, let, if let, while let, let else, for loops, and function/closure parameters.
  • Advanced Control: Features like partial moves and if let chains provide fine-grained control over ownership and conditional logic.

Understanding and utilizing patterns effectively is crucial for writing idiomatic, robust, and maintainable Rust code. They enable developers to handle complex data structures and control flow logic with clarity and the safety guarantees of the Rust compiler.