# 1.2.0[−][src]Struct std::fmt::DebugMap

    #[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.

# Examples

    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()
        }
    }

    // prints "{"A": 10, "B": 11}"
    println!("{:?}", Foo(vec![("A".to_string(), 10), ("B".to_string(), 11)]));Run

## Methods

###

`impl<'a, 'b> DebugMap<'a, 'b> where 'b: 'a,`

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####

`pub fn entry( &mut self, key: &dyn Debug, value: &dyn Debug ) -> &mut DebugMap<'a, 'b>`

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Adds a new entry to the map output.

####

`pub fn entries<K, V, I>(&mut self, entries: I) -> &mut DebugMap<'a, 'b> where I: IntoIterator<Item = (K, V)>, K: Debug, V: Debug,`

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

####

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

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Finishes output and returns any error encountered.

## Auto Trait Implementations

###

`impl<'a, 'b> !Send for DebugMap<'a, 'b>`

###

`impl<'a, 'b> !Sync for DebugMap<'a, 'b>`

## Blanket Implementations

###

`impl<T, U> TryFrom for T where T: From<U>,`

[src]

#### `type Error = !`

🔬 This is a nightly-only experimental API. (`try_from` #33417)

The type returned in the event of a conversion error.

####

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

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🔬 This is a nightly-only experimental API. (`try_from` #33417)

Performs the conversion.

###

`impl<T> From for T`

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####

`fn from(t: T) -> T`

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Performs the conversion.

###

`impl<T, U> TryInto for T where U: TryFrom<T>,`

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

🔬 This is a nightly-only experimental API. (`try_from` #33417)

The type returned in the event of a conversion error.

####

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

[src]

🔬 This is a nightly-only experimental API. (`try_from` #33417)

Performs the conversion.

###

`impl<T, U> Into for T where U: From<T>,`

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####

`fn into(self) -> U`

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Performs the conversion.

###

`impl<T> Borrow for T where T: ?Sized,`

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####
ⓘImportant traits for &'_ mut I

### Important traits for &'_ mut I

`impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'a, R: Read + ?Sized> Read for &'a mut Rimpl<'a, W: Write + ?Sized> Write for &'a mut W`

`fn borrow(&self) -> &T`

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Immutably borrows from an owned value. Read more

###

`impl<T> BorrowMut for T where T: ?Sized,`

[src]

####
ⓘImportant traits for &'_ mut I

### Important traits for &'_ mut I

`impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'a, R: Read + ?Sized> Read for &'a mut Rimpl<'a, W: Write + ?Sized> Write for &'a mut W`

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

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Mutably borrows from an owned value. Read more

###

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

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####

`fn get_type_id(&self) -> TypeId`

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🔬 This is a nightly-only experimental API. (`get_type_id` #27745)

this method will likely be replaced by an associated static

Gets the `TypeId` of `self`. Read more

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