Trait frame_support::dispatch::fmt::Display

1.0.0 · 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.

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§

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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::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, }));

Implementors§

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impl Display for TransactionValidityError

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impl Display for StateVersion

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impl Display for Infallible

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impl Display for VarError

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

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impl Display for IpAddr

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impl Display for SocketAddr

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impl Display for Weight

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impl Display for TryReserveError

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impl Display for FromVecWithNulError

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impl Display for IntoStringError

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impl Display for NulError

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impl Display for FromUtf8Error

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impl Display for FromUtf16Error

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impl Display for String

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impl Display for LayoutError

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impl Display for AllocError

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impl Display for core::array::TryFromSliceError

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impl Display for core::ascii::EscapeDefault

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impl Display for BorrowError

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impl Display for BorrowMutError

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impl Display for CharTryFromError

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impl Display for ParseCharError

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impl Display for DecodeUtf16Error

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impl Display for core::char::EscapeDebug

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impl Display for core::char::EscapeDefault

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impl Display for core::char::EscapeUnicode

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impl Display for ToLowercase

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impl Display for ToUppercase

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impl Display for TryFromCharError

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impl Display for FromBytesUntilNulError

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impl Display for FromBytesWithNulError

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impl Display for core::num::dec2flt::ParseFloatError

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impl Display for ParseIntError

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impl Display for TryFromIntError

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impl Display for NonZeroI8

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impl Display for NonZeroI16

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impl Display for NonZeroI32

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impl Display for NonZeroI64

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impl Display for NonZeroI128

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impl Display for NonZeroIsize

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impl Display for NonZeroU8

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impl Display for NonZeroU16

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impl Display for NonZeroU32

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impl Display for NonZeroU64

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impl Display for NonZeroU128

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impl Display for NonZeroUsize

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impl Display for Location<'_>

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impl Display for PanicInfo<'_>

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impl Display for ParseBoolError

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impl Display for Utf8Error

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impl Display for TryFromFloatSecsError

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impl Display for Backtrace

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impl Display for JoinPathsError

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impl Display for WriterPanicked

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impl Display for std::io::error::Error

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impl Display for Ipv4Addr

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impl Display for Ipv6Addr

Write an Ipv6Addr, conforming to the canonical style described by RFC 5952.

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impl Display for AddrParseError

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impl Display for SocketAddrV4

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impl Display for SocketAddrV6

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impl Display for Display<'_>

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impl Display for StripPrefixError

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impl Display for ExitStatus

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impl Display for ExitStatusError

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impl Display for RecvError

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impl Display for AccessError

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impl Display for SystemTimeError

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impl Display for anyhow::Error

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impl Display for base16ct::display::HexDisplay<'_>

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impl Display for chrono::format::ParseError

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impl Display for NaiveDate

The Display output of the naive date d is the same as d.format("%Y-%m-%d").

The string printed can be readily parsed via the parse method on str.

Example

use chrono::NaiveDate;

assert_eq!(format!("{}", NaiveDate::from_ymd_opt(2015,  9,  5).unwrap()), "2015-09-05");
assert_eq!(format!("{}", NaiveDate::from_ymd_opt(   0,  1,  1).unwrap()), "0000-01-01");
assert_eq!(format!("{}", NaiveDate::from_ymd_opt(9999, 12, 31).unwrap()), "9999-12-31");

ISO 8601 requires an explicit sign for years before 1 BCE or after 9999 CE.

assert_eq!(format!("{}", NaiveDate::from_ymd_opt(   -1,  1,  1).unwrap()),  "-0001-01-01");
assert_eq!(format!("{}", NaiveDate::from_ymd_opt(10000, 12, 31).unwrap()), "+10000-12-31");

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impl Display for NaiveDateTime

The Display output of the naive date and time dt is the same as dt.format("%Y-%m-%d %H:%M:%S%.f").

It should be noted that, for leap seconds not on the minute boundary, it may print a representation not distinguishable from non-leap seconds. This doesn’t matter in practice, since such leap seconds never happened. (By the time of the first leap second on 1972-06-30, every time zone offset around the world has standardized to the 5-minute alignment.)

Example

use chrono::NaiveDate;

let dt = NaiveDate::from_ymd_opt(2016, 11, 15).unwrap().and_hms_opt(7, 39, 24).unwrap();
assert_eq!(format!("{}", dt), "2016-11-15 07:39:24");

Leap seconds may also be used.

let dt = NaiveDate::from_ymd_opt(2015, 6, 30).unwrap().and_hms_milli_opt(23, 59, 59, 1_500).unwrap();
assert_eq!(format!("{}", dt), "2015-06-30 23:59:60.500");

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impl Display for NaiveTime

The Display output of the naive time t is the same as t.format("%H:%M:%S%.f").

The string printed can be readily parsed via the parse method on str.

It should be noted that, for leap seconds not on the minute boundary, it may print a representation not distinguishable from non-leap seconds. This doesn’t matter in practice, since such leap seconds never happened. (By the time of the first leap second on 1972-06-30, every time zone offset around the world has standardized to the 5-minute alignment.)

Example

use chrono::NaiveTime;

assert_eq!(format!("{}", NaiveTime::from_hms_opt(23, 56, 4).unwrap()),              "23:56:04");
assert_eq!(format!("{}", NaiveTime::from_hms_milli_opt(23, 56, 4, 12).unwrap()),    "23:56:04.012");
assert_eq!(format!("{}", NaiveTime::from_hms_micro_opt(23, 56, 4, 1234).unwrap()),  "23:56:04.001234");
assert_eq!(format!("{}", NaiveTime::from_hms_nano_opt(23, 56, 4, 123456).unwrap()), "23:56:04.000123456");

Leap seconds may also be used.

assert_eq!(format!("{}", NaiveTime::from_hms_milli_opt(6, 59, 59, 1_500).unwrap()), "06:59:60.500");

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impl Display for FixedOffset

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impl Display for Utc

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impl Display for Duration

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impl Display for chrono::oldtime::OutOfRangeError

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impl Display for ParseWeekdayError

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impl Display for crypto_mac::errors::InvalidKeyLength

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impl Display for crypto_mac::errors::MacError

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impl Display for getrandom::error::Error

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impl Display for log::ParseLevelError

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impl Display for SetLoggerError

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impl Display for BigInt

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impl Display for BigUint

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impl Display for ParseBigIntError

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impl Display for Buffer

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impl Display for num_format::error::Error

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impl Display for ParseRatioError

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impl Display for num_traits::ParseFloatError

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impl Display for parity_scale_codec::error::Error

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impl Display for Path<PortableForm>

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

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impl Display for serde_json::error::Error

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impl Display for Number

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impl Display for FixedI64

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impl Display for FixedI128

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impl Display for FixedU64

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impl Display for FixedU128

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impl Display for AccountId32

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impl Display for CryptoTypePublicPair

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impl Display for sp_core::ecdsa::Public

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impl Display for sp_core::ed25519::Public

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impl Display for sp_core::sr25519::Public

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impl Display for CodeNotFound

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impl Display for SetGlobalDefaultError

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impl Display for Field

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impl Display for FieldSet

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impl Display for tracing_core::metadata::Level

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impl Display for tracing_core::metadata::LevelFilter

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impl Display for tracing_core::metadata::ParseLevelError

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impl Display for ParseLevelFilterError

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impl Display for tracing_subscriber::filter::directive::ParseError

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impl Display for Directive

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impl Display for BadName

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impl Display for EnvFilter

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impl Display for FromEnvError

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impl Display for tracing_subscriber::reload::Error

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impl Display for TryInitError

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impl Display for Url

Display the serialization of this URL.

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impl Display for getrandom::error::Error

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impl Display for rand::rngs::adapter::read::ReadError

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impl Display for rand::rngs::adapter::read::ReadError

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impl Display for rand_core::error::Error

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impl Display for rand_core::error::Error

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impl Display for Arguments<'_>

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impl Display for frame_support::dispatch::fmt::Error

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impl Display for Aarch64Architecture

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impl Display for Aborted

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impl Display for Architecture

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impl Display for ArmArchitecture

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impl Display for Ast

Print a display representation of this Ast.

This does not preserve any of the original whitespace formatting that may have originally been present in the concrete syntax from which this Ast was generated.

This implementation uses constant stack space and heap space proportional to the size of the Ast.

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