pub trait Display {
// Required method
fn fmt(&self, f: &mut Formatter<'_>) -> Result;
}
Expand description
空格式的格式 trait,{}
。
为一个类型实现这个 trait 将自动为该类型实现 ToString
trait,允许使用 .to_string()
方法。
更喜欢为一个类型实现 Display
trait,而不是 ToString
。
Display
与 Debug
类似,但 Display
是面向用户的输出,因此无法导出。
有关格式化程序的更多信息,请参见 模块级文档。
Examples
在类型上实现 Display
:
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)");
RunRequired Methods§
sourcefn fmt(&self, f: &mut Formatter<'_>) -> Result
fn fmt(&self, f: &mut Formatter<'_>) -> Result
使用给定的格式化程序格式化该值。
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, }));
RunImplementors§
impl Display for AsciiChar
impl Display for Infallible
impl Display for IpAddr
impl Display for SocketAddr
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 AllocError
impl Display for LayoutError
impl Display for TryFromSliceError
impl Display for core::ascii::EscapeDefault
impl Display for BorrowError
impl Display for BorrowMutError
impl Display for CharTryFromError
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 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
编写一个符合 RFC 5952 描述的规范样式的 Ivv6Addr。