RustTutorials/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, and 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{
		write!(f, "RGB ({0}, {1}, {2}) 0x{0:0width$X}{1:0width$X}{2:0width$X}", self.red, self.green, self.blue, width = 2)
	}
}

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(){
		//Switch this to use {} once you've added an implementation
		//for fmt::Display.
		//println!("{:?}", *color);
		println!("{}", *color);
	}
}