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

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

    #[must_use = "must eventually call `finish()` on Debug builders"]pub struct DebugTuple<'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 tuple as a part of your `Debug::fmt` implementation.

This can be constructed by the `Formatter::debug_tuple` method.

# Examples

    use std::fmt;

    struct Foo(i32, String);

    impl fmt::Debug for Foo {
        fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
            fmt.debug_tuple("Foo")
               .field(&self.0)
               .field(&self.1)
               .finish()
        }
    }

    assert_eq!(
        format!("{:?}", Foo(10, "Hello World".to_string())),
        "Foo(10, \"Hello World\")",
    );

Run

## Implementations

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

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

Adds a new field to the generated tuple struct output.

# Examples

    use std::fmt;

    struct Foo(i32, String);

    impl fmt::Debug for Foo {
        fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
            fmt.debug_tuple("Foo")
               .field(&self.0) // We add the first field.
               .field(&self.1) // We add the second field.
               .finish() // We're good to go!
        }
    }

    assert_eq!(
        format!("{:?}", Foo(10, "Hello World".to_string())),
        "Foo(10, \"Hello World\")",
    );

Run

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

Finishes output and returns any error encountered.

# Examples

    use std::fmt;

    struct Foo(i32, String);

    impl fmt::Debug for Foo {
        fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
            fmt.debug_tuple("Foo")
               .field(&self.0)
               .field(&self.1)
               .finish() // You need to call it to "finish" the
                         // tuple formatting.
        }
    }

    assert_eq!(
        format!("{:?}", Foo(10, "Hello World".to_string())),
        "Foo(10, \"Hello World\")",
    );

Run

## Auto Trait Implementations

### `impl<'a, 'b> !Send for DebugTuple<'a, 'b>`

### `impl<'a, 'b> !Sync for DebugTuple<'a, 'b>`

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

## 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.