Struct DebugTuple

#[must_use = "must eventually call `finish()` on Debug builders"]
pub struct DebugTuple<'a, 'b: 'a> { pub(in ::fmt::builders) fmt: &'a mut Formatter<'b>, pub(in ::fmt::builders) result: Result, pub(in ::fmt::builders) fields: usize, pub(in ::fmt::builders) empty_name: bool }

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())),
    r#"Foo(10, "Hello World")"#,
);

Fields

fmt: &'a mut Formatter<'b>
result: Result
fields: usize
empty_name: bool

Implementations

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

fn field(&mut self, value: &dyn Debug) -> &mut Self

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())),
    r#"Foo(10, "Hello World")"#,
);

fn field_with<F>(&mut self, value_fmt: F) -> &mut Self
where
    F: FnOnce(&mut Formatter<'_>) -> Result,

Adds a new field to the generated tuple struct output.

This method is equivalent to DebugTuple::field, but formats the value using a provided closure rather than by calling Debug::fmt.

fn finish_non_exhaustive(&mut self) -> Result

Marks the tuple struct as non-exhaustive, indicating to the reader that there are some other fields that are not shown in the debug representation.

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)
           .finish_non_exhaustive() // Show that some other field(s) exist.
    }
}

assert_eq!(
    format!("{:?}", Foo(10, "secret!".to_owned())),
    "Foo(10, ..)",
);

fn finish(&mut self) -> Result

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())),
    r#"Foo(10, "Hello World")"#,
);

fn is_pretty(&self) -> bool

Auto Trait Implementations

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

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

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

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

impl<'a, 'b> Freeze for DebugTuple<'a, 'b>

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

impl<'a, 'b> UnsafeUnpin for DebugTuple<'a, 'b>

Blanket Implementations

impl<T> Any for DebugTuple<'a, 'b> where T: 'static + ?Sized,

fn type_id(&self) -> TypeId

impl<T> Borrow<T> for DebugTuple<'a, 'b> where T: ?Sized,

fn borrow(&self) -> &T

impl<T> BorrowMut<T> for DebugTuple<'a, 'b> where T: ?Sized,

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

impl<T> From<T> for DebugTuple<'a, 'b>

fn from(t: T) -> T

Returns the argument unchanged.

impl<T> SizeHint for DebugTuple<'a, 'b> where T: ?Sized,

fn lower_bound(&self) -> usize
fn upper_bound(&self) -> Option<usize>

impl<T> SizedTypeProperties for DebugTuple<'a, 'b>

impl<T, U> Into<U> for DebugTuple<'a, 'b> where U: From<T>,

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of [From]<T> for U chooses to do.

impl<T, U> TryFrom<U> for DebugTuple<'a, 'b> where U: Into<T>,

type Error = Infallible;
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

impl<T, U> TryInto<U> for DebugTuple<'a, 'b> where U: TryFrom<T>,

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