Struct alloc::fmt::DebugTuple  1.2.0[−][src]
pub struct DebugTuple<'a, 'b> where
    'b: 'a,  { /* fields omitted */ }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\")",
);Implementations
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\")",
);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\")",
);