Struct alloc::fmt::DebugMap

#[must_use = "must eventually call `finish()` on Debug builders"]
pub struct DebugMap<'a, 'b> where
    'b: 'a,  { /* fields omitted */ }

A struct to help with fmt::Debug implementations.

This is useful when you wish to output a formatted map as a part of your Debug::fmt implementation.

This can be constructed by the Formatter::debug_map method.

Examples

use std::fmt;

struct Foo(Vec<(String, i32)>);

impl fmt::Debug for Foo {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        fmt.debug_map().entries(self.0.iter().map(|&(ref k, ref v)| (k, v))).finish()
    }
}

// prints "{"A": 10, "B": 11}"
println!("{:?}", Foo(vec![("A".to_string(), 10), ("B".to_string(), 11)]));

Methods

impl<'a, 'b> DebugMap<'a, 'b> where     'b: 'a,

pub fn entry(&mut self, key: &Debug, value: &Debug) -> &mut DebugMap<'a, 'b>

Adds a new entry to the map output.

pub fn entries<K, V, I>(&mut self, entries: I) -> &mut DebugMap<'a, 'b> where     I: IntoIterator<Item = (K, V)>,     K: Debug,     V: Debug,

Adds the contents of an iterator of entries to the map output.

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

Finishes output and returns any error encountered.