1.0.0[−][src]Trait uefi_std::convert::AsRef
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
AsRef
when the goal is to simply convert into a reference - Use
Borrow
when the goal is related to writing code that is agnostic to the type of borrow and whether it is a reference or value
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
AsRef
auto-dereferences if the inner type is a reference or a mutable reference (e.g.:foo.as_ref()
will work the same iffoo
has type&mut Foo
or&&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);
Required methods
fn as_ref(&self) -> &T
Performs the conversion.
Implementations on Foreign Types
impl<T> AsRef<T> for Arc<T> where
T: ?Sized,
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T: ?Sized,
Implementors
impl AsRef<[u8]> for str
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impl AsRef<[u8]> for String
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impl AsRef<str> for String
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impl AsRef<str> for str
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impl<'_, T> AsRef<T> for Cow<'_, T> where
T: ToOwned + ?Sized,
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T: ToOwned + ?Sized,
impl<'_, T> AsRef<[T]> for Iter<'_, T>
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impl<'_, T, U> AsRef<U> for &'_ T where
T: AsRef<U> + ?Sized,
U: ?Sized,
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T: AsRef<U> + ?Sized,
U: ?Sized,
impl<'_, T, U> AsRef<U> for &'_ mut T where
T: AsRef<U> + ?Sized,
U: ?Sized,
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T: AsRef<U> + ?Sized,
U: ?Sized,
impl<T> AsRef<Vec<T>> for Vec<T>
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impl<T> AsRef<T> for Box<T> where
T: ?Sized,
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T: ?Sized,
impl<T> AsRef<T> for Rc<T> where
T: ?Sized,
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T: ?Sized,