Trait Display

1.6.0 · Source

pub 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 DisplayCopy item path

§Internationalization

§Examples

Required Methods§

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

§Errors

§Examples

Implementors§

impl Display for Tz

impl Display for clang_sys::Version

impl Display for codespan_reporting::files::Error

impl Display for gimli::read::Error

impl Display for globset::ErrorKind

impl Display for AdditionError

impl Display for CreationError

impl Display for RecordError

impl Display for SubtractionError

impl Display for httparse::Error

impl Display for humantime::date::Error

impl Display for humantime::duration::Error

impl Display for GetTimezoneError

impl Display for CodePointInversionListError

impl Display for CodePointInversionListAndStringListError

impl Display for icu_collections::codepointtrie::error::Error

impl Display for ParserError

impl Display for LocaleTransformError

impl Display for NormalizerError

impl Display for PropertiesError

impl Display for DataErrorKind

impl Display for ignore::Error

impl Display for IpNet

impl Display for libloading::error::Error

impl Display for InsertError

impl Display for matchit::error::MatchError

impl Display for nix::errno::consts::Errno

impl Display for Signal

impl Display for rand::distributions::bernoulli::BernoulliError

impl Display for WeightedError

impl Display for StartError

impl Display for Ast

impl Display for regex_syntax::ast::ErrorKind

impl Display for regex_syntax::error::Error

impl Display for regex_syntax::hir::ErrorKind

impl Display for rustls_pki_types::pem::Error

impl Display for rusty_fork::error::Error

impl Display for Segment

impl Display for serde_urlencoded::ser::Error

impl Display for QuoteError

impl Display for CollectionAllocErr

impl Display for StrSimError

impl Display for TinyStrError

impl Display for AnyDelimiterCodecError

impl Display for LinesCodecError

impl Display for Item

impl Display for toml_edit::ser::Error

impl Display for toml_edit::value::Value

impl Display for ucd_trie::owned::Error

impl Display for GraphemeClusterBreak

impl Display for SentenceBreak

impl Display for WordBreak

impl Display for winnow::error::ErrorKind

impl Display for StrContext

impl Display for StrContextValue

impl Display for BigEndian

impl Display for LittleEndian

impl Display for ZeroVecError

impl Display for rustmax::axum::extract::path::ErrorKind

impl Display for BytesRejection

impl Display for ExtensionRejection

impl Display for FailedToBufferBody

impl Display for FormRejection

impl Display for JsonRejection

impl Display for MatchedPathRejection

impl Display for PathRejection

impl Display for QueryRejection

impl Display for RawFormRejection

impl Display for RawPathParamsRejection

impl Display for StringRejection

impl Display for ParseAlphabetError

impl Display for DecodeError

Trait Display