1.0.0[−][src]Trait core::convert::AsRef
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:
- Unlike
AsRef,Borrowhas a blanket impl for anyT, and can be used to accept either a reference or a value. Borrowalso requires thatHash,EqandOrdfor borrowed value are equivalent to those of the owned value. For this reason, if you want to borrow only a single field of a struct you can implementAsRef, but notBorrow.
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
AsRefauto-dereferences if the inner type is a reference or a mutable reference (e.g.:foo.as_ref()will work the same iffoohas type&mut Fooor&&mut Foo)
Examples
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"; is_hello(s); let s = "hello".to_string(); is_hello(s);Run
Required methods
fn as_ref(&self) -> &T
Performs the conversion.
Implementors
impl AsRef<[u8]> for str[src]
impl AsRef<str> for str[src]
impl<T> AsRef<[T]> for [T][src]
impl<T, '_> AsRef<[T]> for Iter<'_, 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>, [src]
T: AsRef<U>,
impl<T: ?Sized, U: ?Sized, '_> AsRef<U> for &'_ mut T where
T: AsRef<U>, [src]
T: AsRef<U>,