Designing a Library

We will learn much more about structs and the Vec<T> type tomorrow. For now, you just need to know part of its API:

  1. fn main() {
  2.     let mut vec = vec![10, 20];
  3.     vec.push(30);
  4.     println!("middle value: {}", vec[vec.len() / 2]);
  5.     for item in vec.iter() {
  6.         println!("item: {item}");
  7.     }
  8. }

Use this to create a library application. Copy the code below to https://play.rust-lang.org/ and update the types to make it compile:

  1. // TODO: remove this when you're done with your implementation.
  2. #![allow(unused_variables, dead_code)]
  4. struct Library {
  5.     books: Vec<Book>,
  6. }
  8. struct Book {
  9.     title: String,
  10.     year: u16,
  11. }
  13. impl Book {
  14.     // This is a constructor, used below.
  15.     fn new(title: &str, year: u16) -> Book {
  16.         Book {
  17.             title: String::from(title),
  18.             year,
  19.         }
  20.     }
  21. }
  23. // This makes it possible to print Book values with {}.
  24. impl std::fmt::Display for Book {
  25.     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
  26.         write!(f, "{} ({})", self.title, self.year)
  27.     }
  28. }
  30. impl Library {
  31.     fn new() -> Library {
  32.         unimplemented!()
  33.     }
  35.     //fn len(self) -> usize {
  36.     //    unimplemented!()
  37.     //}
  39.     //fn is_empty(self) -> bool {
  40.     //    unimplemented!()
  41.     //}
  43.     //fn add_book(self, book: Book) {
  44.     //    unimplemented!()
  45.     //}
  47.     //fn print_books(self) {
  48.     //    unimplemented!()
  49.     //}
  51.     //fn oldest_book(self) -> Option<&Book> {
  52.     //    unimplemented!()
  53.     //}
  54. }
  56. // This shows the desired behavior. Uncomment the code below and
  57. // implement the missing methods. You will need to update the
  58. // method signatures, including the "self" parameter! You may
  59. // also need to update the variable bindings within main.
  60. fn main() {
  61.     let library = Library::new();
  63.     //println!("Our library is empty: {}", library.is_empty());
  64.     //
  65.     //library.add_book(Book::new("Lord of the Rings", 1954));
  66.     //library.add_book(Book::new("Alice's Adventures in Wonderland", 1865));
  67.     //
  68.     //library.print_books();
  69.     //
  70.     //match library.oldest_book() {
  71.     //    Some(book) => println!("My oldest book is {book}"),
  72.     //    None => println!("My library is empty!"),
  73.     //}
  74.     //
  75.     //println!("Our library has {} books", library.len());
  76. }

Solution