#[must_use = "must eventually call `finish()` on Debug builders"] pub struct DebugMap<'a, 'b> where 'b: 'a, 'b: 'a, 'b: 'b, { /* fields omitted */ }
A struct to help with fmt::Debug implementations.
This is useful when you wish to output a formatted map as a part of your Debug::fmt implementation.
This can be constructed by the Formatter::debug_map method.
use std::fmt; struct Foo(Vec<(String, i32)>); impl fmt::Debug for Foo { fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result { fmt.debug_map().entries(self.0.iter().map(|&(ref k, ref v)| (k, v))).finish() } } assert_eq!( format!("{:?}", Foo(vec![("A".to_string(), 10), ("B".to_string(), 11)])), "{\"A\": 10, \"B\": 11}", );
impl<'a, 'b> DebugMap<'a, 'b> where
'b: 'a, [src]
pub fn entry(
&mut self,
key: &dyn Debug,
value: &dyn Debug
) -> &mut DebugMap<'a, 'b>[src]
Adds a new entry to the map output.
use std::fmt; struct Foo(Vec<(String, i32)>); impl fmt::Debug for Foo { fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { fmt.debug_map() .entry(&"whole", &self.0) // We add the "whole" entry. .finish() } } assert_eq!( format!("{:?}", Foo(vec![("A".to_string(), 10), ("B".to_string(), 11)])), "{\"whole\": [(\"A\", 10), (\"B\", 11)]}", );
pub fn entries<K, V, I>(&mut self, entries: I) -> &mut DebugMap<'a, 'b> where
I: IntoIterator<Item = (K, V)>,
K: Debug,
V: Debug, [src]
Adds the contents of an iterator of entries to the map output.
use std::fmt; struct Foo(Vec<(String, i32)>); impl fmt::Debug for Foo { fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { fmt.debug_map() // We map our vec so each entries' first field will become // the "key". .entries(self.0.iter().map(|&(ref k, ref v)| (k, v))) .finish() } } assert_eq!( format!("{:?}", Foo(vec![("A".to_string(), 10), ("B".to_string(), 11)])), "{\"A\": 10, \"B\": 11}", );
pub fn finish(&mut self) -> Result<(), Error>[src]
Finishes output and returns any error encountered.
use std::fmt; struct Foo(Vec<(String, i32)>); impl fmt::Debug for Foo { fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { fmt.debug_map() .entries(self.0.iter().map(|&(ref k, ref v)| (k, v))) .finish() // Ends the struct formatting. } } assert_eq!( format!("{:?}", Foo(vec![("A".to_string(), 10), ("B".to_string(), 11)])), "{\"A\": 10, \"B\": 11}", );
impl<'a, 'b> !UnwindSafe for DebugMap<'a, 'b>impl<'a, 'b> !RefUnwindSafe for DebugMap<'a, 'b>impl<'a, 'b> Unpin for DebugMap<'a, 'b> where
'b: 'a, impl<'a, 'b> !Send for DebugMap<'a, 'b>impl<'a, 'b> !Sync for DebugMap<'a, 'b>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> Into<U> for T where
U: From<T>, [src]
impl<T> From<T> for T[src]
impl<T, U> TryInto<U> for T where
U: TryFrom<T>, [src]
type Error = <U as TryFrom<T>>::ErrorThe type returned in the event of a conversion error.
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>[src]
impl<T> Borrow<T> for T where
T: ?Sized, [src]
fn borrow(&self) -> &T[src]
impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<'_, R: Read + ?Sized> Read for &'_ mut R
impl<'_, W: Write + ?Sized> Write for &'_ mut W
impl<T> BorrowMut<T> for T where
T: ?Sized, [src]
fn borrow_mut(&mut self) -> &mut T[src]
impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<'_, R: Read + ?Sized> Read for &'_ mut R
impl<'_, W: Write + ?Sized> Write for &'_ mut W
impl<T> Any for T where
T: 'static + ?Sized, [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.DebugMap.html