https://github.com/danielschemmel/fmt-derive

A better `#[derive(Debug, Display)]`
https://github.com/danielschemmel/fmt-derive

Last synced: 6 months ago
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A better `#[derive(Debug, Display)]`

• Host: GitHub
• URL: https://github.com/danielschemmel/fmt-derive
• Owner: danielschemmel
• Created: 2022-09-07T04:57:10.000Z (almost 4 years ago)
• Default Branch: main
• Last Pushed: 2025-02-21T17:59:57.000Z (over 1 year ago)
• Last Synced: 2025-11-24T04:22:20.124Z (7 months ago)
• Language: Rust
• Homepage:
• Size: 61.5 KB
• Stars: 2
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

          
[![crates.io](https://img.shields.io/crates/v/fmt-derive?style=flat-square)](https://crates.io/crates/fmt_derive)

[![docs.rs](https://img.shields.io/docsrs/fmt-derive?style=flat-square)](https://docs.rs/fmt-derive/latest/fmt_derive/)

More robust and versatile implementation of `derive(Debug)` and `derive(Display)`. Unlike the version of`derive(Debug)`

in the standard library, these macros will always successfully generate an implementation - even if a member does not

implement `Debug`/`Display`. In that case, the generated implementation will print a replacement string of the form

``.

```rust

use fmt_derive::Debug; // replacement for `use std::fmt::Debug;`

// a type that implements neither `Debug` nor `Display`

struct Unprintable;

#[derive(Debug, fmt_derive::Display)]

struct Printable {

	// unprintable members will be printed as ``

	unprintable: Unprintable,

	// use `#[display(ignore)]` (or `#[debug(ignore]` respectively) to skip a member when printing

	#[display(ignore)]

	ignored: u32,

	// use the `fmt` attribute to refer to both `Debug` and `Display` at once

	#[fmt("{:#08X}", self.hex_number)]

	hex_number: u32,

}

fn main() {

	let printable = Printable{

		hex_number: 0xDEADBEEF,

		ignored: 42,

		unprintable: Unprintable,

	};

	assert_eq!(format!("{:?}", printable), "Printable { unprintable: , ignored: 42, hex_number: 0xDEADBEEF }");

	assert_eq!(format!("{}", printable), "Printable { unprintable: , hex_number: 0xDEADBEEF }");

}

```

# `no_std`

This crate is `no_std` and can be used from both `no_std` and `std` contexts without any action required.

# MSRV

The current MSRV is 1.69.0. For this project, it is primarily driven by the few dependencies it relies on.