formatting.rs

use std::fmt::{self, Formatter, Display};

struct City {
	name: &'static str,
	// Latitude
	lat: f32,
	// Longitude
	lon: f32,
}

impl Display for City {
	// `f` is a buffer, this method must write the formatted string into it.
	fn fmt(&self, f: &mut Formatter) -> fmt::Result {
		let lat_c = if self.lat >= 0.0 { 'N' } else { 'S' };
		let lon_c = if self.lon >= 0.0 { 'E' } else { 'W' };
		
		// `write!` is like `format!`, but it will write the formatted string
		// into a buffer (the first argument).
		write!(f, "{}: {:.3}°{} {:.3}°{}",
			self.name, self.lat.abs(), lat_c, self.lon.abs(), lon_c)
	}
}

#[derive(Debug)]
struct Color {
	red: u8,
	green: u8,
	blue: u8,
}

impl Display for Color {
	fn fmt(&self, f: &mut Formatter) -> fmt::Result {
		let hex = format!("0x{red:02X?}{green:02X?}{blue:02X?}",
			red = self.red,
			green = self.green,
			blue = self.blue);
		write!(f, "RGB ({red}, {green}, {blue}) {hex}", 
			red = self.red,
			green = self.green,
			blue = self.blue,
			hex = &hex)
	}
}
fn main() {
	for city in [
		City { name: "Dublin", lat: 53.347778, lon: -6.259722 },
		City { name: "Oslo", lat: 59.95, lon: 10.75 },
		City { name: "Vancouver", lat: 49.25, lon: -123.1 },
	].iter() {
		println!("{}", *city);
	}
	for color in [
		Color { red: 128, green: 255, blue: 90 },
		Color { red: 0, green: 3, blue: 254 },
		Color { red: 0, green: 0, blue: 0 },
	].iter() {
		//println!("{:?}", *color);
		println!("{}", *color);
	}
}