std::fmt::DebugList - Rust
Description: API documentation for the Rust `DebugList` struct in crate `std`.
Keywords: rust, rustlang, rust-lang, DebugList

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

    #[must_use = "must eventually call `finish()` on Debug builders"]pub struct DebugList<'a, 'b> where
        'b: 'a,  { /* fields omitted */ }

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

### `impl<'a, 'b> DebugList<'a, 'b> where
'b: 'a,` [src]

#### `pub fn entry(&mut self, entry: &dyn Debug) -> &mut DebugList<'a, 'b>`[src]

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

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

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

#### `pub fn finish(&mut self) -> Result<(), Error>`[src]

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

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `fn type_id(&self) -> TypeId`[src]

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

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `fn borrow(&self) -> &T`[src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `fn borrow_mut(&mut self) -> &mut T`[src]

Mutably borrows from an owned value. Read more

### `impl<T> From<T> for T`[src]

#### `fn from(t: T) -> T`[src]

Performs the conversion.

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `fn into(self) -> U`[src]

Performs the conversion.

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

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

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

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

The type returned in the event of a conversion error.

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

Performs the conversion.