Borrow Checker & References

Created: before i made this website

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  • references point to data without taking ownership
  • created with & for immutable or &mut for mutable references
  • immutable refs: read-only, can have many at once
  • mutable refs: read/write, only one at a time per scope
  • prevents data races and ensures safe concurrency
  • borrowing = using data through a reference instead of owning it
  • borrows must not outlive the data they reference
  • refs automatically dereference when used (no need for * usually)
  •   let mut x = 5;
  let r = &x;       // immutable borrow
  let m = &mut x;   // mutable borrow (only if no immutables exist)
  • compiler enforces borrowing rules at compile time
  • refs are temporary views; ownership returns when they go out of scope