Trait std::convert::AsRef 1.0.0
[−]
[src]
pub trait AsRef<T> where
T: ?Sized, {
fn as_ref(&self) -> &T;
}A cheap reference-to-reference conversion. Used to convert a value to a reference value within generic code.
AsRef is very similar to, but serves a slightly different purpose than,
Borrow.
AsRef is to be used when wishing to convert to a reference of another
type.
Borrow is more related to the notion of taking the reference. It is
useful when wishing to abstract over the type of reference
(&T, &mut T) or allow both the referenced and owned type to be treated
in the same manner.
The key difference between the two traits is the intention:
- Use
AsRefwhen goal is to simply convert into a reference - Use
Borrowwhen goal is related to writing code that is agnostic to the type of borrow and if is reference or value
See the book for a more detailed comparison.
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
Both String and &str implement AsRef<str>:
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
Implementors
impl<'a, T> AsRef<T> for Cow<'a, T> where
T: ToOwned + ?Sized,impl<T> AsRef<T> for Box<T> where
T: ?Sized,impl AsRef<str> for Stringimpl AsRef<[u8]> for Stringimpl<T> AsRef<T> for Rc<T> where
T: ?Sized,impl<T> AsRef<[T]> for Vec<T>impl<T> AsRef<T> for Arc<T> where
T: ?Sized,impl<T> AsRef<Vec<T>> for Vec<T>impl<T> AsRef<[T]> for [T; 31]impl AsRef<[u8]> for strimpl<T> AsRef<[T]> for [T; 14]impl<T> AsRef<[T]> for [T; 7]impl<T> AsRef<[T]> for [T; 24]impl<T> AsRef<[T]> for [T; 28]impl<T> AsRef<[T]> for [T; 0]impl<T> AsRef<[T]> for [T; 19]impl<T> AsRef<[T]> for [T; 9]impl<T> AsRef<[T]> for [T; 18]impl<T> AsRef<[T]> for [T; 20]impl<T> AsRef<[T]> for [T; 17]impl<T> AsRef<[T]> for [T; 22]impl<T> AsRef<[T]> for [T; 11]impl<T> AsRef<[T]> for [T; 32]impl<T> AsRef<[T]> for [T; 10]impl<T> AsRef<[T]> for [T; 21]impl<T> AsRef<[T]> for [T; 2]impl<T> AsRef<[T]> for [T; 16]impl<T> AsRef<[T]> for [T; 23]impl<T> AsRef<[T]> for [T; 15]impl<T> AsRef<[T]> for [T; 4]impl<T> AsRef<[T]> for [T; 30]impl<T> AsRef<[T]> for [T; 6]impl<T> AsRef<[T]> for [T; 13]impl<'a, T, U> AsRef<U> for &'a mut T where
T: AsRef<U> + ?Sized,
U: ?Sized,impl<T> AsRef<[T]> for [T]impl<'a, T> AsRef<[T]> for std::slice::Iter<'a, T>impl<T> AsRef<[T]> for [T; 3]impl<T> AsRef<[T]> for [T; 29]impl<T> AsRef<[T]> for [T; 25]impl<T> AsRef<[T]> for [T; 8]impl<T> AsRef<[T]> for [T; 5]impl<T> AsRef<[T]> for [T; 12]impl AsRef<str> for strimpl<T> AsRef<[T]> for [T; 26]impl<T> AsRef<[T]> for [T; 27]impl<T> AsRef<[T]> for [T; 1]impl<'a, T, U> AsRef<U> for &'a T where
T: AsRef<U> + ?Sized,
U: ?Sized,impl AsRef<CStr> for CStrimpl AsRef<CStr> for CStringimpl AsRef<OsStr> for OsStrimpl AsRef<OsStr> for OsStringimpl AsRef<OsStr> for strimpl AsRef<OsStr> for Stringimpl<'a> AsRef<OsStr> for Component<'a>impl<'a> AsRef<Path> for Components<'a>impl<'a> AsRef<OsStr> for Components<'a>impl<'a> AsRef<Path> for std::path::Iter<'a>impl<'a> AsRef<OsStr> for std::path::Iter<'a>impl AsRef<OsStr> for PathBufimpl AsRef<OsStr> for Pathimpl AsRef<Path> for Pathimpl AsRef<Path> for OsStrimpl<'a> AsRef<Path> for Cow<'a, OsStr>impl AsRef<Path> for OsStringimpl AsRef<Path> for strimpl AsRef<Path> for Stringimpl AsRef<Path> for PathBuf