rust / intermediate
Snippet
Custom Debug and Display Formatting
Rust's formatting traits enable custom output for your types. The Debug trait is auto-derivable and allows {:?} format specifier. Display requires manual implementation and supports {} for user-friendly output. Both traits require returning std::fmt::Result and use the Formatter struct's write! macro. Implementing Display also enables other traits like Octal, Binary, and LowerHex through delegation.
snippet.rs
rust
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use std::fmt;struct Point {x: f64,y: f64,}impl fmt::Debug for Point {fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {write!(f, "Point {{ x: {:.2}, y: {:.2} }}", self.x, self.y)}}impl fmt::Display for Point {fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {write!(f, "({}, {})", self.x, self.y)}}fn main() {let p = Point { x: 3.14159, y: 2.71828 };println!("Display: {}", p);println!("Debug: {:?}", p);}
Breakdown
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impl fmt::Debug for Point
Debug trait enables {:?} formatting with custom representation
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write!(f, "Point {{ x: {:.2}, y: {:.2} }}", self.x, self.y)
Format with 2 decimal places using Formatter's write! macro
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impl fmt::Display for Point
Display enables {} formatting for println! macros
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write!(f, "({}, {})", self.x, self.y)
Simple coordinate format for human-readable output