enums

An enum is destructured similarly:

  1. // `allow` required to silence warnings because only
  2. // one variant is used.
  3. #[allow(dead_code)]
  4. enum Color {
  5.     // These 3 are specified solely by their name.
  6.     Red,
  7.     Blue,
  8.     Green,
  9.     // These likewise tie `u32` tuples to different names: color models.
  10.     RGB(u32, u32, u32),
  11.     HSV(u32, u32, u32),
  12.     HSL(u32, u32, u32),
  13.     CMY(u32, u32, u32),
  14.     CMYK(u32, u32, u32, u32),
  15. }
  17. fn main() {
  18.     let color = Color::RGB(122, 17, 40);
  19.     // TODO ^ Try different variants for `color`
  21.     println!("What color is it?");
  22.     // An `enum` can be destructured using a `match`.
  23.     match color {
  24.         Color::Red   => println!("The color is Red!"),
  25.         Color::Blue  => println!("The color is Blue!"),
  26.         Color::Green => println!("The color is Green!"),
  27.         Color::RGB(r, g, b) =>
  28.             println!("Red: {}, green: {}, and blue: {}!", r, g, b),
  29.         Color::HSV(h, s, v) =>
  30.             println!("Hue: {}, saturation: {}, value: {}!", h, s, v),
  31.         Color::HSL(h, s, l) =>
  32.             println!("Hue: {}, saturation: {}, lightness: {}!", h, s, l),
  33.         Color::CMY(c, m, y) =>
  34.             println!("Cyan: {}, magenta: {}, yellow: {}!", c, m, y),
  35.         Color::CMYK(c, m, y, k) =>
  36.             println!("Cyan: {}, magenta: {}, yellow: {}, key (black): {}!",
  37.                 c, m, y, k),
  38.         // Don't need another arm because all variants have been examined
  39.     }
  40. }

See also:

#[allow(...)], color models and enum