trait OutlinePrint: fmt::Display { fn outline_print(&self) { let output = self.to_string(); let len = output.len(); println!("{}", "*".repeat(len + 4)); println!("*{}*", " ".repeat(len + 2)); println!("* {} *", output); println!("*{}*", " ".repeat(len + 2)); println!("{}", "*".repeat(len + 4)); } } struct Point { x: i32, y: i32, } impl OutlinePrint for Point {} // ANCHOR: here use std::fmt; impl fmt::Display for Point { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { write!(f, "({}, {})", self.x, self.y) } } // ANCHOR_END: here fn main() { let p = Point { x: 1, y: 3 }; p.outline_print(); }