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

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, }),
);

Implementors§

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impl Display for AsciiChar

1.34.0 · Source§

impl Display for Infallible

1.17.0 · Source§

impl Display for FromBytesWithNulError

1.7.0 · Source§

impl Display for IpAddr

1.0.0 · Source§

impl Display for SocketAddr

1.86.0 · Source§

impl Display for core::slice::GetDisjointMutError

1.29.0 · Source§

impl Display for proc_macro::TokenTree

Prints the token tree as a string that is supposed to be losslessly convertible back into the same token tree (modulo spans), except for possibly TokenTree::Groups with Delimiter::None delimiters and negative numeric literals.

Note: the exact form of the output is subject to change, e.g. there might be changes in the whitespace used between tokens. Therefore, you should not do any kind of simple substring matching on the output string (as produced by to_string) to implement a proc macro, because that matching might stop working if such changes happen. Instead, you should work at the TokenTree level, e.g. matching against TokenTree::Ident, TokenTree::Punct, or TokenTree::Literal.

1.0.0 · Source§

impl Display for VarError

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impl Display for std::fs::TryLockError

1.60.0 · Source§

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

1.15.0 · Source§

impl Display for RecvTimeoutError

1.0.0 · Source§

impl Display for proc_macro2::TokenTree

impl Display for FromBytesUntilNulError

1.0.0 · Source§

impl Display for Ipv4Addr

1.0.0 · Source§

impl Display for Ipv6Addr

1.29.0 · Source§

impl Display for proc_macro::Ident

Prints the identifier as a string that should be losslessly convertible back into the same identifier.

1.44.0 · Source§

impl Display for proc_macro::LexError

1.29.0 · Source§

impl Display for proc_macro::Literal

Prints the literal as a string that should be losslessly convertible back into the same literal (except for possible rounding for floating point literals).

1.29.0 · Source§

impl Display for proc_macro::Punct

Prints the punctuation character as a string that should be losslessly convertible back into the same character.

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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 proc_macro2::Group

Prints the group as a string that should be losslessly convertible back into the same group (modulo spans), except for possibly TokenTree::Groups with Delimiter::None delimiters.

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impl Display for proc_macro2::Ident

Prints the identifier as a string that should be losslessly convertible back into the same identifier.

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impl Display for proc_macro2::LexError

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impl Display for proc_macro2::Literal

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impl Display for proc_macro2::Punct

Prints the punctuation character as a string that should be losslessly convertible back into the same character.

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impl Display for proc_macro2::TokenStream

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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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.

The format returned by this implementation is not stable and must not be relied upon.

By default this produces an exact, full-precision printout of the duration. For a concise, rounded printout instead, you can use the .N format specifier:

let duration = Duration::new(123456, 789011223);
println!("{duration:.3}");

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impl Display for Hir

Print a display representation of this Hir.

The result of this is a valid regular expression pattern string.

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

Display the name of the address format (not the description).

assert_eq!(format!("{}", StatusCode::OK), "200 OK");

TOML parse error at line 1, column 10 | 1 | 00:32:00.a999999 | ^ Unexpected a Expected digit While parsing a Time While parsing a Date-Time

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impl<P, const N: usize> Display for Fp<P, N>
where P: FpConfig<N>,

Outputs a string containing the value of self, represented as a decimal without leading zeroes.

impl Display for HashedLaneId

impl Display for Error

impl Display for RelayChainError

impl<E: Error> Display for Error<E>

impl Display for SizeType

impl Display for DatabaseSize

impl Display for BenchmarkOutput

impl Display for NsFormatter

impl Display for Public

impl Display for ClientError

impl Display for EthRpcError

impl<AccountId> Display for SessionReport<AccountId>

impl<AccountId> Display for ValidatorSetReport<AccountId>

impl Display for Error

impl Display for DisputeMessageCreationError

impl Display for Error

impl Display for InvalidCandidate

impl Display for PossiblyInvalidError

impl Display for ValidationError

impl Display for InternalValidationError

impl Display for PrepareError

impl Display for JobError

impl Display for WorkerError

impl Display for WorkerKind

impl Display for Error

impl Display for FatalError

impl Display for JfyiError

impl Display for RequestError

impl Display for ProtocolVersion

impl Display for WrongVariant

impl Display for ApprovalError

impl Display for Error

impl Display for MerkleProofError

impl Display for InvalidAssignment

impl Display for FatalRecoveryError

impl Display for JfyiRecoveryError

impl Display for RecoveryError

impl Display for RuntimeApiError

impl Display for SubsystemError

impl Display for ApprovalCheckError

impl Display for AssignmentCheckError

impl Display for StoreAvailableDataError

impl Display for ChainApiError

impl Display for ValidationFailed

impl Display for FetchError

impl Display for Error

impl Display for FatalError

impl Display for JfyiError

impl Display for AuthoringPolicy

impl Display for BlockNumber

impl Display for Error

impl Display for FatalError

impl Display for JfyiError

impl Display for Strategy

impl Display for TestConfiguration

impl Display for BenchmarkUsage

impl Display for ResourceUsage

impl Display for Error

impl Display for StringifiedMaybeConnectionError

impl Display for Error

impl Display for WasmExecutionMethod

impl Display for Error

impl Display for MemorySize

impl Display for UsageInfo

impl Display for DatabaseSource

impl Display for BlockImportError

impl Display for PreDigestLookupError

impl<B: BlockT> Display for Error

impl<Header> Display for SealVerificationError<Header>

impl<B: BlockT> Display for Error

impl Display for Error

impl Display for FinalityProofError

impl Display for Error

impl<B: BlockT> Display for Error

impl Display for Error

impl Display for WasmError

impl Display for Backtrace

impl Display for MessageWithBacktrace

impl Display for Error

impl Display for RemoteErr

impl Display for ParseErr

impl Display for RequestFailure

impl Display for Error

impl Display for InboundFailure

impl Display for OutboundFailure

impl Display for RegisterError

impl Display for ResponseFailure

impl Display for NotificationSenderError

impl Display for ProtocolName

impl Display for MultiaddrWithPeerId

impl Display for Role

impl Display for StateSyncPhase

impl Display for BadPeer

impl<Block: BlockT> Display for WarpSyncPhase<Block>

impl Display for DecodingError

impl Display for ParseError

impl Display for Protocol<'_>

impl Display for Error

impl Display for SigningError

impl Display for Multiaddr

impl Display for PeerId

impl Display for Error

impl Display for UnsafeRpcError

impl Display for Health

impl Display for Error

impl Display for ErrorBroadcast

impl Display for Error

impl<Block: BlockT> Display for Error<Block>
where Error<Block>: Display,

impl Display for Throughput

impl Display for Error

impl Display for FastLocalTime

impl Display for Values

impl Display for Error

impl Display for SeqID

impl Display for ApplyExtrinsicFailed

impl Display for Error

impl Display for NoProofRecorded

impl Display for Public

impl<AuthorityId> Display for Keyring<AuthorityId>

impl<N: Debug, S> Display for VersionedFinalityProof<N, S>

impl<TBlockNumber: Debug, TSignature> Display for SignedCommitment<TBlockNumber, TSignature>

impl Display for DatabaseError

impl Display for Error

impl Display for MixnodesErr

impl Display for Error

impl<Hash, HeaderNumber> Display for Error<Hash, HeaderNumber>
where HeaderNumber: Display + Debug + MaybeDisplay, Hash: Display + Debug + MaybeDisplay,

Trait DisplayCopy item path

§Internationalization

§Examples

Required Methods§

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

§Errors

§Examples

Implementors§

impl Display for AsciiChar

impl Display for Infallible

impl Display for FromBytesWithNulError

impl Display for IpAddr

impl Display for SocketAddr

impl Display for core::slice::GetDisjointMutError

impl Display for proc_macro::TokenTree

impl Display for VarError

impl Display for std::fs::TryLockError

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

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 num_format::error_kind::ErrorKind

impl Display for proc_macro2::TokenTree

impl Display for serde_json::value::Value

impl Display for BernoulliError

impl Display for WeightedError

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 BridgeMessageDispatchError

impl Display for xcm_emulator::ParaId

impl Display for Weight

impl Display for ByteString

impl Display for UnorderedKeyError

impl Display for alloc::collections::TryReserveError

impl Display for FromVecWithNulError

impl Display for IntoStringError

impl Display for NulError

impl Display for FromUtf8Error

impl Display for FromUtf16Error

impl Display for String

impl Display for LayoutError

impl Display for core::alloc::AllocError

impl Display for core::array::TryFromSliceError

impl Display for core::ascii::EscapeDefault

impl Display for ByteStr

impl Display for BorrowError

impl Display for BorrowMutError

impl Display for CharTryFromError

impl Display for core::char::convert::ParseCharError

impl Display for DecodeUtf16Error

impl Display for core::char::EscapeDebug

impl Display for core::char::EscapeDefault

impl Display for core::char::EscapeUnicode

impl Display for ToLowercase

impl Display for ToUppercase

impl Display for TryFromCharError

impl Display for FromBytesUntilNulError

impl Display for Ipv4Addr

impl Display for Ipv6Addr

impl Display for AddrParseError

impl Display for SocketAddrV4

impl Display for SocketAddrV6

Trait Display