# Struct std::fmt::DebugTuple

1.2.0 · source ·

    pub struct DebugTuple<'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 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§

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### impl<'a, 'b> DebugTuple<'a, 'b>where 'b: 'a,

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

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

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§

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

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

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

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### impl<'a, 'b> Unpin for DebugTuple<'a, 'b>

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

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

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

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

Returns the argument unchanged.

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

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

Performs the conversion.