Trait Display

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1.0.0 · Source

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

Expand description

🖹 core Format trait for an empty format, {}.

Re-exported from core::fmt:: .

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.

§Completeness and parseability

Display for a type might not necessarily be a lossless or complete representation of the type. It may omit internal state, precision, or other information the type does not consider important for user-facing output, as determined by the type. As such, the output of Display might not be possible to parse, and even if it is, the result of parsing might not exactly match the original value.

However, if a type has a lossless Display implementation whose output is meant to be conveniently machine-parseable and not just meant for human consumption, then the type may wish to accept the same format in FromStr, and document that usage. Having both Display and FromStr implementations where the result of Display cannot be parsed with FromStr may surprise users.

§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 DisplayCopy item path

§Completeness and parseability

§Internationalization

§Examples

Required Methods§

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

§Errors

§Examples

Implementors§

impl Display for devela::_core::ascii::Char

impl Display for FromBytesWithNulError

impl Display for devela::_core::slice::GetDisjointMutError

impl Display for devela::_dep::_std::fs::TryLockError

impl Display for CheckedCastError

impl Display for PodCastError

impl Display for SetCursorStyle

impl Display for KeyCode

impl Display for MediaKeyCode

impl Display for ModifierKeyCode

impl Display for Attribute

impl Display for Colored

impl Display for devela::_dep::ffmpeg_the_third::Error

impl Display for ParsePixelError

impl Display for devela::_dep::flume::RecvError

impl Display for devela::_dep::flume::RecvTimeoutError

impl Display for devela::_dep::flume::TryRecvError

impl Display for devela::_dep::gilrs::Error

impl Display for MappingError

impl Display for DistanceModelError

impl Display for devela::_dep::gilrs::ff::Error

impl Display for devela::_dep::image::ImageError

impl Display for ImageFormatHint

impl Display for devela::_dep::image::flat::Error

impl Display for devela::_dep::kira::backend::cpal::Error

impl Display for FromFileError

impl Display for ConnectErrorKind

impl Display for PortInfoError

impl Display for devela::_dep::midir::SendError

impl Display for ShaderError

impl Display for ShaderType

impl Display for devela::_dep::miniquad::fs::Error

impl Display for EglError

impl Display for X11Error

impl Display for devela::_dep::miniquad::native::module::Error

impl Display for Associativity

impl Display for CacheType

impl Display for DatType

impl Display for ExtendedRegisterStateLocation

impl Display for ExtendedRegisterType

impl Display for TopologyType

impl Display for DecoderError

impl Display for devela::_dep::rodio::decoder::symphonia::SeekError

impl Display for devela::_dep::rodio::source::SeekError

impl Display for AddMappingError

impl Display for devela::_dep::sdl2::Error

impl Display for IntegerOrSdlError

impl Display for PrefPathError

impl Display for Scancode

impl Display for ShowMessageError

impl Display for TargetRenderError

impl Display for TextureValueError

impl Display for UpdateTextureError

impl Display for UpdateTextureYUVError

impl Display for FontError

impl Display for OpenUrlError

impl Display for WindowBuildError

impl Display for devela::_dep::symphonia::core::errors::Error

impl Display for devela::_dep::symphonia::core::meta::Value

impl Display for DiskKind

impl Display for ProcessStatus

impl Display for Signal

impl Display for devela::_dep::tokio::sync::broadcast::error::RecvError

impl Display for devela::_dep::tokio::sync::broadcast::error::TryRecvError

impl Display for TryAcquireError

impl Display for devela::_dep::tokio::sync::mpsc::error::TryRecvError

impl Display for devela::_dep::tokio::sync::oneshot::error::TryRecvError

impl Display for Item

impl Display for devela::_dep::toml_edit::Offset

impl Display for devela::_dep::toml_edit::Value

impl Display for devela::_dep::toml_edit::ser::Error

Trait Display