Struct std::fmt::DebugList

1.2.0 · source ·
pub struct DebugList<'a, 'b>where
    'b: 'a,
{ /* private fields */ }
Expand description

A struct to help with fmt::Debug implementations.

This is useful when you wish to output a formatted list of items as a part of your Debug::fmt implementation.

This can be constructed by the Formatter::debug_list method.

Examples

use std::fmt;

struct Foo(Vec<i32>);

impl fmt::Debug for Foo {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        fmt.debug_list().entries(self.0.iter()).finish()
    }
}

assert_eq!(
    format!("{:?}", Foo(vec![10, 11])),
    "[10, 11]",
);
Run

Implementations§

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impl<'a, 'b> DebugList<'a, 'b>where
    'b: 'a,

source

pub fn entry(&mut self, entry: &dyn Debug) -> &mut DebugList<'a, 'b>

Adds a new entry to the list output.

Examples
use std::fmt;

struct Foo(Vec<i32>, Vec<u32>);

impl fmt::Debug for Foo {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt.debug_list()
           .entry(&self.0) // We add the first "entry".
           .entry(&self.1) // We add the second "entry".
           .finish()
    }
}

assert_eq!(
    format!("{:?}", Foo(vec![10, 11], vec![12, 13])),
    "[[10, 11], [12, 13]]",
);
Run
source

pub fn entries<D, I>(&mut self, entries: I) -> &mut DebugList<'a, 'b>where
    D: Debug,
    I: IntoIterator<Item = D>,

Adds the contents of an iterator of entries to the list output.

Examples
use std::fmt;

struct Foo(Vec<i32>, Vec<u32>);

impl fmt::Debug for Foo {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt.debug_list()
           .entries(self.0.iter())
           .entries(self.1.iter())
           .finish()
    }
}

assert_eq!(
    format!("{:?}", Foo(vec![10, 11], vec![12, 13])),
    "[10, 11, 12, 13]",
);
Run
source

pub fn finish(&mut self) -> Result<(), Error>

Finishes output and returns any error encountered.

Examples
use std::fmt;

struct Foo(Vec<i32>);

impl fmt::Debug for Foo {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt.debug_list()
           .entries(self.0.iter())
           .finish() // Ends the struct formatting.
    }
}

assert_eq!(
    format!("{:?}", Foo(vec![10, 11])),
    "[10, 11]",
);
Run

Auto Trait Implementations§

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impl<'a, 'b> !RefUnwindSafe for DebugList<'a, 'b>

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impl<'a, 'b> !Send for DebugList<'a, 'b>

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impl<'a, 'b> !Sync for DebugList<'a, 'b>

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impl<'a, 'b> Unpin for DebugList<'a, 'b>where
    'b: 'a,

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impl<'a, 'b> !UnwindSafe for DebugList<'a, 'b>

Blanket Implementations§

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impl<T> Any for Twhere
    T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere
    T: ?Sized,

const: unstable · source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere
    T: ?Sized,

const: unstable · source§

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

const: unstable · source§

fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for Twhere
    U: From<T>,

const: unstable · source§

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T, U> TryFrom<U> for Twhere
    U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
const: unstable · source§

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere
    U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
const: unstable · source§

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.