Trait debug2::Debug

source · [−]
pub trait Debug {
    fn fmt(&self, f: &mut Formatter<'_>) -> Result;
}
Expand description

Pretty Printed Formatting

This is much like std::fmt::Debug, but it supports much better multiline output

Examples

use debug2::{pprint, Debug};

#[derive(Debug)]
struct Numbers {
    a: Vec<Vec<i32>>,
    b: String,
}

let a = Numbers {
    a: vec![vec![10; 10]; 2],
    b: "FooBar".to_owned(),
};

assert_eq!(
    pprint(&a),
    "\
Numbers {
    a: [
        [10, 10, 10, 10, 10, 10, 10, 10, 10, 10],
        [10, 10, 10, 10, 10, 10, 10, 10, 10, 10],
    ],
    b: \"FooBar\",
}"
);

You can also implement fmt manually, using an API much like std::fmt::Formatter

use debug2::{pprint, Debug, Formatter};
use std::fmt;

struct Chunked10([u8; 100]);

impl Debug for Chunked10 {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        f.debug_list().entries(self.0.chunks(10)).finish()
    }
}

assert_eq!(
    pprint(Chunked10([0; 100])),
    "\
[
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
]"
);

Required methods

Formats the value using the given formatter.

Note that this may be called more than once for any invocation of pprint, if you do side effects in this, make sure they are idempotent. In general, don’t relly on how often this function is called, as it may change in a future release.

Implementations on Foreign Types

Implementors