DebugTuple in core::fmt - Rust (original) (raw)

Struct DebugTuple

1.6.0 · Source

pub struct DebugTuple<'a, '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 yourDebug::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")"#,
);

Source§

1.2.0 · Source

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")"#,
);

Source

🔬This is a nightly-only experimental API. (debug_closure_helpers #117729)

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.

1.83.0 · Source

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, ..)",
);

1.2.0 · Source

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")"#,
);

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