Trait core::convert::AsRef1.0.0[][src]

pub trait AsRef<T: ?Sized> {
    fn as_ref(&self) -> &T;

Used to do a cheap reference-to-reference conversion.

This trait is similar to AsMut which is used for converting between mutable references. If you need to do a costly conversion it is better to implement From with type &T or write a custom function.

AsRef has the same signature as Borrow, but Borrow is different in few aspects:

Note: This trait must not fail. If the conversion can fail, use a dedicated method which returns an Option<T> or a Result<T, E>.

Generic Implementations


By using trait bounds we can accept arguments of different types as long as they can be converted to the specified type T.

For example: By creating a generic function that takes an AsRef<str> we express that we want to accept all references that can be converted to &str as an argument. Since both String and &str implement AsRef<str> we can accept both as input argument.

fn is_hello<T: AsRef<str>>(s: T) {
   assert_eq!("hello", s.as_ref());

let s = "hello";

let s = "hello".to_string();

Required methods

fn as_ref(&self) -> &T[src]

Performs the conversion.

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impl AsRef<[u8]> for str[src]

impl AsRef<str> for str[src]

impl<T> AsRef<[T]> for Iter<'_, T>1.13.0[src]

impl<T> AsRef<[T]> for [T][src]

impl<T, const N: usize> AsRef<[T]> for [T; N][src]

impl<T: ?Sized, U: ?Sized> AsRef<U> for &T where
    T: AsRef<U>, 

impl<T: ?Sized, U: ?Sized> AsRef<U> for &mut T where
    T: AsRef<U>, 

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