Expand description
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 a few aspects:
- Unlike
AsRef
,Borrow
has a blanket impl for anyT
, and can be used to accept either a reference or a value. Borrow
also requires thatHash
,Eq
andOrd
for a 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
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
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);
Required Methods
Implementors
impl AsRef<str> for SVGWidthOrHeight
impl AsRef<str> for Signal
impl AsRef<str> for Algorithm
impl AsRef<str> for str
impl AsRef<str> for Url
Return the serialization of this URL.
impl AsRef<str> for String
impl AsRef<str> for HeaderName
impl AsRef<str> for Method
impl AsRef<str> for Authority
impl AsRef<str> for Scheme
impl AsRef<str> for Mime
impl AsRef<str> for OpensslString
impl AsRef<str> for OpensslStringRef
impl AsRef<str> for SaltString
impl AsRef<str> for Field
impl AsRef<str> for UncasedStr
impl AsRef<sigset_t> for SigSet
impl AsRef<sockaddr_alg> for AlgAddr
impl AsRef<sockaddr_in6> for SockaddrIn6
impl AsRef<sockaddr_in> for SockaddrIn
impl AsRef<sockaddr_ll> for LinkAddr
impl AsRef<sockaddr_nl> for NetlinkAddr
impl AsRef<sockaddr_un> for UnixAddr
impl AsRef<sockaddr_vm> for VsockAddr
impl AsRef<timespec> for TimeSpec
impl AsRef<timeval> for TimeVal
impl AsRef<SystemTime> for Timestamp
impl AsRef<Duration> for Duration
impl AsRef<HtmlStr> for Html
impl AsRef<HtmlStr> for HtmlLit
impl AsRef<HtmlStr> for HtmlStr
impl AsRef<Instant> for Instant
impl AsRef<OsStr> for str
impl AsRef<OsStr> for OsStr
impl AsRef<OsStr> for PathBuf
impl AsRef<OsStr> for TempPath
impl AsRef<OsStr> for String
impl AsRef<OsStr> for OsString
impl AsRef<OsStr> for Path
impl AsRef<CStr> for CStr
impl AsRef<CStr> for CString
impl AsRef<Vec<u8, Global>> for ByteBuf
impl AsRef<Path> for str
impl AsRef<Path> for NamedTempFile
impl AsRef<Path> for OsStr
impl AsRef<Path> for PathBuf
impl AsRef<Path> for TempDir
impl AsRef<Path> for TempPath
impl AsRef<Path> for String
impl AsRef<Path> for OsString
impl AsRef<Path> for Path
impl AsRef<Asn1BitStringRef> for Asn1BitString
impl AsRef<Asn1GeneralizedTimeRef> for Asn1GeneralizedTime
impl AsRef<Asn1IntegerRef> for Asn1Integer
impl AsRef<Asn1ObjectRef> for Asn1Object
impl AsRef<Asn1StringRef> for Asn1String
impl AsRef<Asn1TimeRef> for Asn1Time
impl AsRef<BigNumContextRef> for BigNumContext
impl AsRef<BigNumRef> for BigNum
impl AsRef<CipherCtxRef> for CipherCtx
impl AsRef<CmsContentInfoRef> for CmsContentInfo
impl AsRef<ConfRef> for Conf
impl AsRef<EcGroupRef> for EcGroup
impl AsRef<EcPointRef> for EcPoint
impl AsRef<EcdsaSigRef> for EcdsaSig
impl AsRef<MdCtxRef> for MdCtx
impl AsRef<OcspBasicResponseRef> for OcspBasicResponse
impl AsRef<OcspCertIdRef> for OcspCertId
impl AsRef<OcspOneReqRef> for OcspOneReq
impl AsRef<OcspRequestRef> for OcspRequest
impl AsRef<OcspResponseRef> for OcspResponse
impl AsRef<Pkcs7Ref> for Pkcs7
impl AsRef<Pkcs12Ref> for Pkcs12
impl AsRef<SrtpProtectionProfileRef> for SrtpProtectionProfile
impl AsRef<SslContextRef> for SslContext
impl AsRef<SslRef> for Ssl
impl AsRef<SslSessionRef> for SslSession
impl AsRef<OpensslStringRef> for OpensslString
impl AsRef<X509StoreBuilderRef> for X509StoreBuilder
impl AsRef<X509StoreRef> for X509Store
impl AsRef<AccessDescriptionRef> for AccessDescription
impl AsRef<GeneralNameRef> for GeneralName
impl AsRef<X509AlgorithmRef> for X509Algorithm
impl AsRef<X509ExtensionRef> for X509Extension
impl AsRef<X509NameEntryRef> for X509NameEntry
impl AsRef<X509NameRef> for X509Name
impl AsRef<X509ObjectRef> for X509Object
impl AsRef<X509Ref> for X509
impl AsRef<X509Ref> for X509Ref
impl AsRef<X509ReqRef> for X509Req
impl AsRef<X509StoreContextRef> for X509StoreContext
impl AsRef<X509VerifyParamRef> for X509VerifyParam
impl AsRef<Opts> for Opts
impl AsRef<BStr> for str
impl AsRef<BStr> for BString
impl AsRef<BStr> for [u8]
impl AsRef<FileSizeOpts> for FileSizeOpts
impl AsRef<Semaphore> for PollSemaphore
impl AsRef<TcpStream> for OwnedReadHalf
impl AsRef<TcpStream> for OwnedWriteHalf
impl AsRef<UnixStream> for OwnedReadHalf
impl AsRef<UnixStream> for OwnedWriteHalf
impl AsRef<[u8]> for str
impl AsRef<[u8]> for String
impl AsRef<[u8]> for h2::ext::Protocol
impl AsRef<[u8]> for HeaderName
impl AsRef<[u8]> for HeaderValue
impl AsRef<[u8]> for DigestBytes
impl AsRef<[u8]> for OpensslString
impl AsRef<[u8]> for OpensslStringRef
impl AsRef<[u8]> for Output
impl AsRef<[u8]> for BStr
impl AsRef<[u8]> for BString
impl AsRef<[u8]> for ByteBuf
impl AsRef<[u8]> for Bytes
impl AsRef<[u8]> for BytesMut
impl AsRef<[u8]> for Literal
impl AsRef<[u8]> for Protocol
impl AsRef<[u8]> for UncasedStr
impl AsRef<dyn Error + 'static> for otter_nodejs_tests::otter_support::crates::anyhow::Error
impl AsRef<dyn Error + Send + Sync + 'static> for otter_nodejs_tests::otter_support::crates::anyhow::Error
impl AsRef<dyn Fail + 'static> for Error
impl<'_> AsRef<OsStr> for Component<'_>
impl<'_> AsRef<OsStr> for Components<'_>
impl<'_> AsRef<OsStr> for std::path::Iter<'_>
impl<'_> AsRef<Path> for Cow<'_, OsStr>
impl<'_> AsRef<Path> for Component<'_>
impl<'_> AsRef<Path> for Components<'_>
impl<'_> AsRef<Path> for std::path::Iter<'_>
impl<'_> AsRef<TcpStream> for ReadHalf<'_>
impl<'_> AsRef<TcpStream> for WriteHalf<'_>
impl<'_> AsRef<UnixStream> for ReadHalf<'_>
impl<'_> AsRef<UnixStream> for WriteHalf<'_>
impl<'_, T> AsRef<[T]> for otter_nodejs_tests::inventory::core::slice::Iter<'_, T>
impl<'_, T> AsRef<[T]> for IterMut<'_, T>
impl<'_, T> AsRef<T> for Cow<'_, T> where
T: ToOwned + ?Sized,
impl<'_, T, U> AsRef<U> for &T where
T: AsRef<U> + ?Sized,
U: ?Sized,
impl<'_, T, U> AsRef<U> for &mut T where
T: AsRef<U> + ?Sized,
U: ?Sized,
impl<'a> AsRef<str> for alloc::string::Drain<'a>
impl<'a> AsRef<str> for Name<'a>
impl<'a> AsRef<str> for Ident<'a>
impl<'a> AsRef<str> for Salt<'a>
impl<'a> AsRef<str> for Value<'a>
impl<'a> AsRef<[u8]> for alloc::string::Drain<'a>
impl<'a, T, A> AsRef<[T]> for alloc::vec::drain::Drain<'a, T, A> where
A: Allocator,
impl<'s, T> AsRef<[T]> for SliceVec<'s, T>
impl<A> AsRef<[<A as Array>::Item]> for ArrayVec<A> where
A: Array,
impl<A> AsRef<[<A as Array>::Item]> for SmallVec<A> where
A: Array,
impl<A> AsRef<[<A as Array>::Item]> for TinyVec<A> where
A: Array,
impl<I, A> AsRef<[A]> for IndexSlice<I, [A]> where
I: Idx,
impl<I, A> AsRef<[A]> for IndexVec<I, A> where
I: Idx,
impl<I, A> AsRef<IndexSlice<I, [A]>> for IndexVec<I, A> where
I: Idx,
impl<L, R> AsRef<str> for Either<L, R> where
L: AsRef<str>,
R: AsRef<str>,
impl<L, R> AsRef<OsStr> for Either<L, R> where
L: AsRef<OsStr>,
R: AsRef<OsStr>,
Requires crate feature use_std
.
impl<L, R> AsRef<CStr> for Either<L, R> where
L: AsRef<CStr>,
R: AsRef<CStr>,
Requires crate feature use_std
.
impl<L, R> AsRef<Path> for Either<L, R> where
L: AsRef<Path>,
R: AsRef<Path>,
Requires crate feature use_std
.