Trait sn0int::fmt::Debug

1.0.0 · source ·

pub trait Debug {
    // Required method
    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>;
}

Expand description

? formatting.

Debug should format the output in a programmer-facing, debugging context.

Generally speaking, you should just derive a Debug implementation.

When used with the alternate format specifier #?, the output is pretty-printed.

For more information on formatters, see the module-level documentation.

This trait can be used with #[derive] if all fields implement Debug. When derived for structs, it will use the name of the struct, then {, then a comma-separated list of each field’s name and Debug value, then }. For enums, it will use the name of the variant and, if applicable, (, then the Debug values of the fields, then ).

Stability

Derived Debug formats are not stable, and so may change with future Rust versions. Additionally, Debug implementations of types provided by the standard library (std, core, alloc, etc.) are not stable, and may also change with future Rust versions.

Examples

Deriving an implementation:

#[derive(Debug)]
struct Point {
    x: i32,
    y: i32,
}

let origin = Point { x: 0, y: 0 };

assert_eq!(format!("The origin is: {origin:?}"), "The origin is: Point { x: 0, y: 0 }");

Manually implementing:

use std::fmt;

struct Point {
    x: i32,
    y: i32,
}

impl fmt::Debug for Point {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Point")
         .field("x", &self.x)
         .field("y", &self.y)
         .finish()
    }
}

let origin = Point { x: 0, y: 0 };

assert_eq!(format!("The origin is: {origin:?}"), "The origin is: Point { x: 0, y: 0 }");

There are a number of helper methods on the Formatter struct to help you with manual implementations, such as debug_struct.

Types that do not wish to use the standard suite of debug representations provided by the Formatter trait (debug_struct, debug_tuple, debug_list, debug_set, debug_map) can do something totally custom by manually writing an arbitrary representation to the Formatter.

impl fmt::Debug for Point {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "Point [{} {}]", self.x, self.y)
    }
}

Debug implementations using either derive or the debug builder API on Formatter support pretty-printing using the alternate flag: {:#?}.

Pretty-printing with #?:

#[derive(Debug)]
struct Point {
    x: i32,
    y: i32,
}

let origin = Point { x: 0, y: 0 };

assert_eq!(format!("The origin is: {origin:#?}"),
"The origin is: Point {
    x: 0,
    y: 0,
}");

Required Methods§

source

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

Examples

use std::fmt;

struct Position {
    longitude: f32,
    latitude: f32,
}

impl fmt::Debug for Position {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_tuple("")
         .field(&self.longitude)
         .field(&self.latitude)
         .finish()
    }
}

let position = Position { longitude: 1.987, latitude: 2.983 };
assert_eq!(format!("{position:?}"), "(1.987, 2.983)");

assert_eq!(format!("{position:#?}"), "(
    1.987,
    2.983,
)");

Trait sn0int::fmt::Debug

Stability

Examples

Required Methods§

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Examples

Implementors§

impl Debug for sn0int::args::SubCommand

impl Debug for RuleType

impl Debug for ActivityGrade

impl Debug for DateArg

impl Debug for sn0int::cmd::add_cmd::Target

impl Debug for sn0int::cmd::autonoscope_cmd::Subcommand

impl Debug for sn0int::cmd::export_cmd::Format

impl Debug for sn0int::cmd::keyring_cmd::Args

impl Debug for sn0int::cmd::notify_cmd::Subcommand

impl Debug for sn0int::cmd::pkg_cmd::SubCommand

impl Debug for SubCommandInteractive

impl Debug for DbChange

impl Debug for Family

impl Debug for sn0int::filters::Target

impl Debug for Insert

impl Debug for sn0int::models::Update

impl Debug for PslReader

impl Debug for sn0int::shell::Command

impl Debug for ReadlineError

impl Debug for DatabaseEvent

impl Debug for DatabaseResponse

impl Debug for Event2

impl Debug for sn0int::worker::Event

impl Debug for ExitEvent

impl Debug for LogEvent

impl Debug for StdioEvent

impl Debug for webpki::error::Error

impl Debug for TryReserveErrorKind

impl Debug for AsciiChar

impl Debug for core::cmp::Ordering

impl Debug for Infallible

impl Debug for Which

impl Debug for c_void

impl Debug for core::fmt::Alignment

impl Debug for core::net::ip_addr::IpAddr

impl Debug for Ipv6MulticastScope

impl Debug for core::net::socket_addr::SocketAddr

impl Debug for FpCategory

impl Debug for IntErrorKind

impl Debug for SearchStep

impl Debug for core::sync::atomic::Ordering

impl Debug for BacktraceStatus

impl Debug for VarError

impl Debug for std::io::SeekFrom

impl Debug for std::io::error::ErrorKind

impl Debug for std::net::Shutdown

impl Debug for AncillaryError

impl Debug for BacktraceStyle

impl Debug for std::sync::mpsc::RecvTimeoutError

impl Debug for std::sync::mpsc::TryRecvError

impl Debug for _Unwind_Reason_Code

impl Debug for time::ParseError

impl Debug for atty::Stream

impl Debug for CapSet

impl Debug for Capability

impl Debug for SecondsFormat

impl Debug for Colons

impl Debug for Fixed

impl Debug for chrono::format::Numeric

impl Debug for chrono::format::OffsetPrecision

impl Debug for Pad

impl Debug for chrono::format::ParseErrorKind

impl Debug for chrono::month::Month

impl Debug for RoundingError

impl Debug for chrono::weekday::Weekday

impl Debug for chrootable_https::cache::Value

impl Debug for DnsError

impl Debug for chrootable_https::dns::RData

impl Debug for Shell

impl Debug for colored::color::Color

impl Debug for colored::style::Styles

impl Debug for crossbeam_channel::err::RecvTimeoutError

impl Debug for crossbeam_channel::err::TryRecvError