Struct DebugTuple 

pub struct DebugTuple<'a, 'b>
where
    'b: 'a,
{ /* private fields */ }

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")"#,
);

Implementations

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

where 'b: 'a,

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

pub fn field_with<F>(&mut self, value_fmt: F) -> &mut DebugTuple<'a, 'b>

where F: FnOnce(&mut Formatter<'_>) -> Result<(), Error>,

🔬This is a nightly-only experimental API. (debug_closure_helpers)

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.

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

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, ..)",
);

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

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 24 bytes