Trait wasmtime_environ::__core::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.
§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 · sourcefn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>
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§
impl Display for gimli::read::Error
impl Display for ConvertError
impl Display for gimli::write::Error
impl Display for leb128::read::Error
impl Display for Level
impl Display for LevelFilter
impl Display for postcard::error::Error
impl Display for CollectionAllocErr
impl Display for target_lexicon::parse_error::ParseError
impl Display for Aarch64Architecture
impl Display for Architecture
impl Display for ArmArchitecture
impl Display for BinaryFormat
impl Display for Environment
impl Display for Mips32Architecture
impl Display for Mips64Architecture
impl Display for OperatingSystem
impl Display for Riscv32Architecture
impl Display for Riscv64Architecture
impl Display for Vendor
impl Display for X86_32Architecture
impl Display for PrimitiveValType
impl Display for StorageType
impl Display for UnpackedIndex
impl Display for ValType
impl Display for CompileError
impl Display for EngineOrModuleTypeIndex
impl Display for FlagValue<'_>
impl Display for Trap
impl Display for WasmCompositeType
impl Display for WasmError
impl Display for WasmHeapType
impl Display for WasmStorageType
impl Display for WasmValType
impl Display for AsciiChar
impl Display for Infallible
impl Display for IpAddr
impl Display for SocketAddr
impl Display for VarError
impl Display for ErrorKind
impl Display for RecvTimeoutError
impl Display for TryRecvError
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 allocator_api2::stable::alloc::AllocError
impl Display for allocator_api2::stable::raw_vec::TryReserveError
impl Display for anyhow::Error
impl Display for bitflags::parser::ParseError
impl Display for DwAccess
impl Display for DwAddr
impl Display for DwAt
impl Display for DwAte
impl Display for DwCc
impl Display for DwCfa
impl Display for DwChildren
impl Display for DwDefaulted
impl Display for DwDs
impl Display for DwDsc
impl Display for DwEhPe
impl Display for DwEnd
impl Display for DwForm
impl Display for DwId
impl Display for DwIdx
impl Display for DwInl
impl Display for DwLang
impl Display for DwLle
impl Display for DwLnct
impl Display for DwLne
impl Display for DwLns
impl Display for DwMacro
impl Display for DwOp
impl Display for DwOrd
impl Display for DwRle
impl Display for DwSect
impl Display for DwSectV2
impl Display for DwTag
impl Display for DwUt
impl Display for DwVirtuality
impl Display for DwVis
impl Display for indexmap::TryReserveError
impl Display for ParseLevelError
impl Display for SetLoggerError
impl Display for object::read::Error
impl Display for SectionIndex
impl Display for SymbolIndex
impl Display for object::write::Error
impl Display for semver::parse::Error
impl Display for BuildMetadata
impl Display for Comparator
impl Display for Prerelease
impl Display for Version
impl Display for VersionReq
impl Display for serde::de::value::Error
impl Display for Triple
impl Display for ColorChoiceParseError
impl Display for ParseColorError
impl Display for BinaryReaderError
impl Display for CompositeType
impl Display for PackedIndex
impl Display for RefType
impl Display for SubType
impl Display for ComponentName
impl Display for KebabStr
impl Display for KebabString
impl Display for String
impl Display for SizeOverflow
impl Display for WasmArrayType
impl Display for WasmFieldType
impl Display for WasmFuncType
impl Display for WasmRefType
impl Display for WasmStructType
impl Display for WasmSubType
impl Display for wasmtime_environ::__core::alloc::AllocError
impl Display for LayoutError
impl Display for TryFromSliceError
impl Display for wasmtime_environ::__core::ascii::EscapeDefault
impl Display for BorrowError
impl Display for BorrowMutError
impl Display for CharTryFromError
impl Display for DecodeUtf16Error
impl Display for wasmtime_environ::__core::char::EscapeDebug
impl Display for wasmtime_environ::__core::char::EscapeDefault
impl Display for wasmtime_environ::__core::char::EscapeUnicode
impl Display for ParseCharError
impl Display for ToLowercase
impl Display for ToUppercase
impl Display for TryFromCharError
impl Display for FromBytesUntilNulError
impl Display for FromBytesWithNulError
impl Display for AddrParseError
impl Display for Ipv4Addr
impl Display for Ipv6Addr
Writes an Ipv6Addr, conforming to the canonical style described by RFC 5952.