Trait ockam_core::compat::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§

1.0.0 · 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 ockam_core::compat::fmt::DebugCopy item path

§Stability

§Examples

Required Methods§

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

§Examples

Implementors§

impl Debug for Method

impl Debug for ockam_core::api::Status

impl Debug for AddressParseErrorKind

impl Debug for RouteError

impl Debug for ockam_core::errcode::Kind

impl Debug for Origin

impl Debug for ockam_core::compat::io::ErrorKind

impl Debug for SeekFrom

impl Debug for IpAddr

impl Debug for Ipv6MulticastScope

impl Debug for Shutdown

impl Debug for ockam_core::compat::net::SocketAddr

impl Debug for BernoulliError

impl Debug for WeightedError

impl Debug for ockam_core::compat::fmt::Alignment

impl Debug for TryReserveErrorKind

impl Debug for AsciiChar

impl Debug for core::cmp::Ordering

impl Debug for Infallible

impl Debug for c_void

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 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 crossbeam_channel::err::RecvTimeoutError

impl Debug for crossbeam_channel::err::TryRecvError

impl Debug for PollNext

impl Debug for hashbrown::TryReserveError

impl Debug for FromHexError

impl Debug for log::Level

impl Debug for log::LevelFilter

impl Debug for MietteError

impl Debug for miette::protocol::Severity

impl Debug for IanaTag

impl Debug for Type

impl Debug for Size

impl Debug for TargetGround

impl Debug for Color

impl Debug for FloatErrorKind

impl Debug for Array

impl Debug for opentelemetry::common::Value

impl Debug for opentelemetry::global::error_handler::Error

impl Debug for LogError

impl Debug for AnyValue

impl Debug for opentelemetry::logs::record::Severity

impl Debug for MetricsError

impl Debug for TraceError

impl Debug for SpanKind

impl Debug for opentelemetry::trace::span::Status

impl Debug for SamplingDecision

impl Debug for Aggregation

impl Debug for Temporality

impl Debug for InstrumentKind

impl Debug for opentelemetry_sdk::runtime::TrySendError

impl Debug for Sampler

impl Debug for IndexVec

impl Debug for IndexVecIntoIter

impl Debug for regex_automata::error::ErrorKind

impl Debug for WhichCaptures

impl Debug for State

impl Debug for regex_automata::util::look::Look

impl Debug for Anchored

impl Debug for MatchErrorKind

impl Debug for MatchKind

impl Debug for regex_syntax::ast::AssertionKind

impl Debug for regex_syntax::ast::AssertionKind

Trait ockam_core::compat::fmt::Debug