This crate provides declarative macros to help you implement the Debug trait manually.
For structs,
```rust
use std::fmt::{self, Formatter, Debug};
pub struct A { pub f1: u8, pub f2: i16, pub f3: f64, }
impl Debug for A { fn fmt(&self, f: &mut Formatter<'>) -> Result<(), fmt::Error> { impldebugforstruct!(A, f, self, .f1, (.f3, "{:.3}", self.f3)); } }
let a = A { f1: 1, f2: 2, f3: std::f64::consts::PI, };
println!("{:#?}", a);
/* A { f1: 1, f3: 3.142, } */ ```
For tuple structs,
```rust
use std::fmt::{self, Formatter, Debug};
pub struct A(pub u8, pub i16, pub f64);
impl Debug for A { fn fmt(&self, f: &mut Formatter<'>) -> Result<(), fmt::Error> { impldebugfortuple_struct!(A, f, self, .0, (.2, "{:.3}", self.2)); } }
let a = A(1, 2, std::f64::consts::PI);
println!("{:#?}", a);
/* A( 1, 3.142, ) */ ```
For enums,
```rust
use std::fmt::{self, Formatter, Debug};
pub enum A { V1, V2(u8, i16, f64), V3 { f1: u8, f2: i16, f3: f64, }, }
impl Debug for A { fn fmt(&self, f: &mut Formatter<'>) -> Result<(), fmt::Error> { impldebugforenum!(A::{V1, (V2(f1, _, f3): (.f1, (.f3, "{:.3}", f3))), {V3{f1, f2: _, f3}: (.f1, (.f3, "{:.3}", f3))}}, f, self); } }
let a = A::V1; let b = A::V2(1, 2, std::f64::consts::PI); let c = A::V3{ f1: 1, f2: 2, f3: std::f64::consts::PI, };
println!("{:#?}", a); println!("{:#?}", b); println!("{:#?}", c);
/* V1 V2( 1, 3.142, ) V3 { f1: 1, f3: 3.142, } */ ```
In most cases, you can use the derivative crate to implement the Debug trait.
https://crates.io/crates/debug-helper
https://docs.rs/debug-helper