pub struct Arguments<'a> { /* fields omitted */ }
This structure represents a safely precompiled version of a format string and its arguments. This cannot be generated at runtime because it cannot safely be done, so no constructors are given and the fields are private to prevent modification.
The format_args! macro will safely create an instance of this structure. The macro validates the format string at compile-time so usage of the write() and format() functions can be safely performed.
You can use the Arguments<'a> that format_args! returns in Debug and Display contexts as seen below. The example also shows that Debug and Display format to the same thing: the interpolated format string in format_args!.
let debug = format!("{:?}", format_args!("{} foo {:?}", 1, 2));
let display = format!("{}", format_args!("{} foo {:?}", 1, 2));
assert_eq!("1 foo 2", display);
assert_eq!(display, debug);impl<'a> Arguments<'a>[src]
pub fn as_str(&self) -> Option<&'static str>[src]
Get the formatted string, if it has no arguments to be formatted.
This can be used to avoid allocations in the most trivial case.
#![feature(fmt_as_str)]
use core::fmt::Arguments;
fn write_str(_: &str) { /* ... */ }
fn write_fmt(args: &Arguments) {
if let Some(s) = args.as_str() {
write_str(s)
} else {
write_str(&args.to_string());
}
}
#![feature(fmt_as_str)]
assert_eq!(format_args!("hello").as_str(), Some("hello"));
assert_eq!(format_args!("").as_str(), Some(""));
assert_eq!(format_args!("{}", 1).as_str(), None);impl<'a> Clone for Arguments<'a>[src]
impl<'a> Copy for Arguments<'a>[src]
impl<'_> Debug for Arguments<'_>[src]
impl<'_> Display for Arguments<'_>[src]
impl<'a> !RefUnwindSafe for Arguments<'a>impl<'a> !Send for Arguments<'a>impl<'a> !Sync for Arguments<'a>impl<'a> Unpin for Arguments<'a>impl<'a> !UnwindSafe for Arguments<'a>impl<T> Any for T where
    T: 'static + ?Sized, [src]
impl<T> Borrow<T> for T where
    T: ?Sized, [src]
fn borrow(&self) -> &TⓘNotable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized,Â
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized,Â
type Item = <I as Iterator>::Item;
impl<R:Â Read + ?Sized, '_> Read for &'_ mut R
impl<W:Â Write + ?Sized, '_> Write for &'_ mut W
[src]
impl<T> BorrowMut<T> for T where
    T: ?Sized, [src]
fn borrow_mut(&mut self) -> &mut TⓘNotable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized,Â
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized,Â
type Item = <I as Iterator>::Item;
impl<R:Â Read + ?Sized, '_> Read for &'_ mut R
impl<W:Â Write + ?Sized, '_> Write for &'_ mut W
[src]
impl<T> From<T> for T[src]
impl<T, U> Into<U> for T where
    U: From<T>, [src]
impl<T> ToOwned for T where
    T: Clone, [src]
type Owned = TThe resulting type after obtaining ownership.
fn to_owned(&self) -> T[src]
fn clone_into(&self, target: &mut T)[src]
impl<T> ToString for T where
    T: Display + ?Sized, [src]
impl<T, U> TryFrom<U> for T where
    U: Into<T>, [src]
type Error = InfallibleThe type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>[src]
impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, [src]
© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/fmt/struct.Arguments.html