Trait kernel::fmt::Display

1.0.0 · source ·

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

Expand description

Format trait for an empty format, {}.

Implementing this trait for a type will automatically implement the ToString trait for the type, allowing the usage of the .to_string() method. Prefer implementing the Display trait for a type, rather than ToString.

Display is similar to Debug, but Display is for user-facing output, and so cannot be derived.

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

§Internationalization

Because a type can only have one Display implementation, it is often preferable to only implement Display when there is a single most “obvious” way that values can be formatted as text. This could mean formatting according to the “invariant” culture and “undefined” locale, or it could mean that the type display is designed for a specific culture/locale, such as developer logs.

If not all values have a justifiably canonical textual format or if you want to support alternative formats not covered by the standard set of possible formatting traits, the most flexible approach is display adapters: methods like str::escape_default or Path::display which create a wrapper implementing Display to output the specific display format.

§Examples

Implementing Display on a type:

use std::fmt;

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

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

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

assert_eq!(format!("The origin is: {origin}"), "The origin is: (0, 0)");

Required Methods§

1.0.0 · source

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

Formats the value using the given formatter.

§Errors

This function should return Err if, and only if, the provided Formatter returns Err. String formatting is considered an infallible operation; this function only returns a Result because writing to the underlying stream might fail and it must provide a way to propagate the fact that an error has occurred back up the stack.

§Examples

use std::fmt;

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

impl fmt::Display for Position {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "({}, {})", self.longitude, self.latitude)
    }
}

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

Trait kernel::fmt::DisplayCopy item path

§Internationalization

§Examples

Required Methods§

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

§Errors

§Examples

Implementors§

impl Display for embedded_hal::digital::ErrorKind

impl Display for embedded_hal::i2c::ErrorKind

impl Display for NoAcknowledgeSource

impl Display for embedded_hal::pwm::ErrorKind

impl Display for embedded_hal::serial::ErrorKind

impl Display for embedded_hal::spi::ErrorKind

impl Display for TimerError

impl Display for TryAcquireError

impl Display for WaitError

impl Display for postcard::error::Error

impl Display for DecodeError

impl Display for EncodeError

impl Display for Variant

impl Display for RegistrationError

impl Display for UserHandlerError

impl Display for AsciiChar

impl Display for Infallible

impl Display for IpAddr

impl Display for SocketAddr

impl Display for VarError

impl Display for std::io::error::ErrorKind

impl Display for RecvTimeoutError

impl Display for std::sync::mpsc::TryRecvError

impl Display for bool

impl Display for char

impl Display for f32

impl Display for f64

impl Display for i8

impl Display for i16

impl Display for i32

impl Display for i64

impl Display for i128

impl Display for isize

impl Display for !

impl Display for str

impl Display for u8

impl Display for u16

impl Display for u32

impl Display for u64

impl Display for u128

impl Display for usize

impl Display for Point

impl Display for Size

impl Display for futures_channel::mpsc::SendError

impl Display for futures_channel::mpsc::TryRecvError

impl Display for Canceled

impl Display for EnterError

impl Display for SpawnError

impl Display for Aborted

impl Display for getrandom::error::Error

impl Display for TaskId

impl Display for Instant

impl Display for Elapsed

impl Display for Closed

impl Display for MetaId

impl Display for num_traits::ParseFloatError

impl Display for serde::de::value::Error

impl Display for tracing_core::dispatch::SetGlobalDefaultError

impl Display for tracing_core::field::Field

impl Display for tracing_core::field::FieldSet

impl Display for tracing_core::metadata::Level

impl Display for tracing_core::metadata::LevelFilter

impl Display for tracing_core::metadata::ParseLevelError

impl Display for tracing_core::metadata::ParseLevelFilterError

impl Display for uuid::error::Error

impl Display for Braced

impl Display for Hyphenated

impl Display for Simple

impl Display for Urn

impl Display for Uuid

impl Display for kernel::serial_trace::field::Field

impl Display for kernel::serial_trace::field::FieldSet

Trait kernel::fmt::Display