display_with

Return opaque impl Display and/or impl Debug types via display_with and debug_with.

Installation

cargo add display_with

Usage

use display_with::{display_with, debug_with};

let display = display_with(|f| write!(f, "Hello, world!"));
assert_eq!(format!("{display}"), "Hello, world!");

let debug = debug_with(|f| write!(f, "Hello, world!"));
assert_eq!(format!("{debug:?}"), "Hello, world!");

This can be combined with the format_args! macro to use the opaque types with the write! and writeln! macros.

use core::fmt::Write;
use display_with::{display_with, debug_with};
fn main() -> std::fmt::Result {
    let display = display_with(|f| write!(f, "Hello, world!"));
    let mut s = String::new();
    // Unlike `s.push_str(&format!("{display}"))`, this doesn't require an extra allocation.
    write!(&mut s, "{}", format_args!("{display}"))?;
    Ok(())
}

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.