RustTutorials/display.rs

use std::fmt;	//Import `fmt`

//A structure holding two numbers. `Debug` will be derived so the results can
//be contrasted with `Display`.
#[derive(Debug)]
struct MinMax(i64, i64);
//Implement `Display` for `MinMax`.
impl fmt::Display for MinMax{
	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result{
		//Use `self.number` to refer to each positional data point.
		write!(f, "({}, {})", self.0, self.1)
	}
}

//Define a structure where the fields are nameable for comparison.
#[derive(Debug)]
struct Point2D{
	x: f64,
	y: f64,
}
//Similarly, implement `Display` for `Point2D`
impl fmt::Display for Point2D{
	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result{
		//Customize so only `x` and `y` are denoted.
		write!(f, "x: {}, y: {}", self.x, self.y)
	}
}

//Define a structure for complex numbers
#[derive(Debug)]
struct Complex{
	real: f64,
	imag: f64,
}
//Implement 'Display' for Complex
impl fmt::Display for Complex{
	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result{
		write!(f, "{} + {}i", self.real, self.imag)
	}
}

fn main(){
	let minmax = MinMax(0, 14);

	println!("Compare structures:");
	println!("Display: {}", minmax);
	println!("Debug: {:?}", minmax);

	let big_range =   MinMax(-300, 300);
	let small_range = MinMax(-3, 3);

	println!("The big range is {big} and the small is {small}",
			 small = small_range,
			 big = big_range);

	let point = Point2D { x: 3.3, y: 7.2 };

	println!("Compare points:");
	println!("Display: {}", point);
	println!("Debug: {:?}", point);

	//Error. Both `Debug` and `Display` were implemented, but `{:b}`
	//requires `fmt::Binary` to be implemented. This will not work.
	//println!("What does Point2D look like in binary: {:b}?", point);

	//Print a test for Complex
	let comp = Complex{real: 3.3, imag: 7.2};
	println!("Compare Complex:");
	println!("Display: {}", comp);
	println!("debug: {:?}", comp);
}