DebugList in alloc::fmt - Rust
Description: A struct to help with `fmt::Debug` implementations.
Keywords: rust, rustlang, rust-lang, DebugList

# Struct alloc::fmt::DebugList
1.2.0[−][src]

    pub struct DebugList<'a, 'b> where
        'b: 'a,  { /* fields omitted */ }

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,

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

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
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#### 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

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

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

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

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

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

## Blanket Implementations

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

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#### pub fn type_id(&self) -> TypeId

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

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

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#### pub fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more

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

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#### pub 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

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#### pub fn from(t: T) -> T

Performs the conversion.

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

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#### pub fn into(self) -> U

Performs the conversion.

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### impl<T, U> TryFrom<U> for T where
U: Into<T>,

#### type Error = Infallible

The type returned in the event of a conversion error.

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#### pub 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 T where
U: TryFrom<T>,

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

The type returned in the event of a conversion error.

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

Performs the conversion.