cosmic::cctk::sctk::reexports::client::backend::smallvec::alloc::fmt

Trait Display

1.36.0 · Source

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

Available on crate feature wayland and Linux only.

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.

§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 cosmic::cosmic_config::Error

impl Display for cosmic::cosmic_theme::palette::rgb::FromHexError

impl Display for cosmic::dialog::file_chooser::Error

impl Display for SurfaceError

impl Display for cosmic::iced::daemon::program::graphics::core::window::icon::Error

impl Display for cosmic::iced::daemon::program::graphics::core::window::screenshot::CropError

impl Display for cosmic::iced::daemon::program::graphics::Error

impl Display for cosmic::iced::daemon::program::graphics::futures::futures::channel::mpsc::TryRecvError

impl Display for cosmic::iced::daemon::program::graphics::futures::futures::io::ErrorKind

impl Display for Align

impl Display for Wrap

impl Display for cosmic::iced::daemon::program::graphics::text::cosmic_text::fontdb::Language

impl Display for PaintError

impl Display for DrawError

impl Display for cosmic::iced::daemon::program::graphics::text::cosmic_text::skrifa::outline::error::CffError

impl Display for ToPathError

impl Display for ReadError

impl Display for Opcode

impl Display for cosmic::iced::daemon::program::graphics::text::cosmic_text::skrifa::raw::tables::postscript::Number

impl Display for InvalidTag

impl Display for cosmic::iced::daemon::program::runtime::image::Error

impl Display for HandleError

impl Display for cosmic::iced::ContentFit

impl Display for cosmic::iced::Error

impl Display for Infallible

impl Display for cosmic::iced::Theme

impl Display for cosmic::iced::window::icon::Error

impl Display for DataOfferError

impl Display for cosmic::cctk::sctk::error::GlobalError

impl Display for Capability

impl Display for SeatError

impl Display for KeyboardError

impl Display for PointerThemeError

impl Display for CreatePoolError

impl Display for PoolError

impl Display for ActivateSlotError

impl Display for CreateBufferError

impl Display for cosmic::cctk::sctk::reexports::calloop::Error

impl Display for CursorIcon

impl Display for cosmic::cctk::sctk::reexports::client::ConnectError

impl Display for cosmic::cctk::sctk::reexports::client::DispatchError

impl Display for cosmic::cctk::sctk::reexports::client::globals::BindError

impl Display for cosmic::cctk::sctk::reexports::client::globals::GlobalError

impl Display for WaylandError

impl Display for CollectionAllocErr

impl Display for cosmic::cctk::sctk::reexports::client::backend::smallvec::alloc::slice::GetDisjointMutError

impl Display for AsciiChar

impl Display for FromBytesWithNulError

impl Display for IpAddr

impl Display for SocketAddr

impl Display for proc_macro::TokenTree

impl Display for VarError

impl Display for std::fs::TryLockError

impl Display for RecvTimeoutError

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

impl Display for hex::error::FromHexError

impl Display for log::Level

impl Display for log::LevelFilter

impl Display for proc_macro2::TokenTree

impl Display for ron::error::Error

impl Display for ron::error::Error

impl Display for serde_json::value::Value

impl Display for url::parser::ParseError

impl Display for SyntaxViolation

impl Display for uuid::Variant

impl Display for BernoulliError

impl Display for rand::distr::uniform::Error

impl Display for rand::distr::weighted::Error

impl Display for bool

impl Display for char

impl Display for f16

Trait Display