Trait scale_info::prelude::cmp::Eq

1.0.0 · source ·

pub trait Eq: PartialEq { }

Expand description

Trait for comparisons corresponding to equivalence relations.

This means, that in addition to a == b and a != b being strict inverses, the relation must be (for all a, b and c):

reflexive: a == a;
symmetric: a == b implies b == a (required by PartialEq as well); and
transitive: a == b and b == c implies a == c (required by PartialEq as well).

This property cannot be checked by the compiler, and therefore Eq implies PartialEq, and has no extra methods.

Violating this property is a logic error. The behavior resulting from a logic error is not specified, but users of the trait must ensure that such logic errors do not result in undefined behavior. This means that unsafe code must not rely on the correctness of these methods.

Implement Eq in addition to PartialEq if it’s guaranteed that PartialEq::eq(a, a) always returns true (reflexivity), in addition to the symmetric and transitive properties already required by PartialEq.

§Derivable

This trait can be used with #[derive]. When derived, because Eq has no extra methods, it is only informing the compiler that this is an equivalence relation rather than a partial equivalence relation. Note that the derive strategy requires all fields are Eq, which isn’t always desired.

§How can I implement `Eq`?

If you cannot use the derive strategy, specify that your type implements Eq, which has no methods:

enum BookFormat { Paperback, Hardback, Ebook }
struct Book {
    isbn: i32,
    format: BookFormat,
}
impl PartialEq for Book {
    fn eq(&self, other: &Self) -> bool {
        self.isbn == other.isbn
    }
}
impl Eq for Book {}

Object Safety§

This trait is not object safe.

Trait scale_info::prelude::cmp::EqCopy item path

§Derivable

§How can I implement Eq?

Object Safety§

Implementors§

impl Eq for byte_slice_cast::Error

impl Eq for PathError

impl Eq for TypeDefPrimitive

impl Eq for MetaForm

impl Eq for PortableForm

impl Eq for TryReserveErrorKind

impl Eq for scale_info::prelude::fmt::Alignment

impl Eq for FpCategory

impl Eq for IntErrorKind

impl Eq for scale_info::prelude::sync::atomic::Ordering

impl Eq for RecvTimeoutError

impl Eq for TryRecvError

impl Eq for scale_info::prelude::cmp::Ordering

impl Eq for AsciiChar

impl Eq for Infallible

impl Eq for IpAddr

impl Eq for Ipv6MulticastScope

impl Eq for SocketAddr

impl Eq for SearchStep

impl Eq for BacktraceStatus

impl Eq for VarError

impl Eq for SeekFrom

impl Eq for ErrorKind

impl Eq for Shutdown

impl Eq for BacktraceStyle

impl Eq for bool

impl Eq for char

impl Eq for i8

impl Eq for i16

impl Eq for i32

impl Eq for i64

impl Eq for i128

impl Eq for isize

impl Eq for !

impl Eq for str

impl Eq for u8

impl Eq for u16

impl Eq for u32

impl Eq for u64

impl Eq for u128

impl Eq for ()

impl Eq for usize

impl Eq for Lsb0

impl Eq for Msb0

impl Eq for Bytes

impl Eq for BytesMut

impl Eq for OptionBool

impl Eq for parity_scale_codec::error::Error

impl Eq for Const

impl Eq for Mut

impl Eq for NullPtrError

impl Eq for MetaType

impl Eq for PortableRegistry

impl Eq for PortableType

impl Eq for Registry

impl Eq for TypeId

impl Eq for UnorderedKeyError

impl Eq for TryReserveError

impl Eq for scale_info::prelude::fmt::Error

impl Eq for PhantomPinned

impl Eq for Assume

impl Eq for ParseFloatError

impl Eq for ParseIntError

impl Eq for TryFromIntError

impl Eq for RangeFull

impl Eq for FromUtf8Error

impl Eq for String

impl Eq for RecvError

impl Eq for WaitTimeoutResult

impl Eq for Duration

impl Eq for Instant

impl Eq for SystemTime

impl Eq for TryFromFloatSecsError

impl Eq for CString

impl Eq for FromVecWithNulError

Trait scale_info::prelude::cmp::Eq

§How can I implement `Eq`?

impl<'a, T> Eq for CompactRef<'a, T>
where T: Eq,

impl<'a, T, O> Eq for IterOnes<'a, T, O>
where T: Eq + 'a + BitStore, O: Eq + BitOrder,

impl<'a, T, O> Eq for IterZeros<'a, T, O>
where T: Eq + 'a + BitStore, O: Eq + BitOrder,

impl<A> Eq for &A
where A: Eq + ?Sized,

impl<A> Eq for &mut A
where A: Eq + ?Sized,

impl<A, O> Eq for BitArray<A, O>
where A: BitViewSized, O: BitOrder,

impl<B> Eq for Cow<'_, B>
where B: Eq + ToOwned + ?Sized,

impl<B, C> Eq for ControlFlow<B, C>
where B: Eq, C: Eq,

impl<Dyn> Eq for DynMetadata<Dyn>
where Dyn: ?Sized,

impl<F> Eq for F
where F: FnPtr,

impl<Idx> Eq for scale_info::prelude::ops::Range<Idx>
where Idx: Eq,

impl<Idx> Eq for scale_info::prelude::ops::RangeFrom<Idx>
where Idx: Eq,

impl<Idx> Eq for scale_info::prelude::ops::RangeInclusive<Idx>
where Idx: Eq,

impl<Idx> Eq for RangeTo<Idx>
where Idx: Eq,

impl<Idx> Eq for RangeToInclusive<Idx>
where Idx: Eq,

impl<Idx> Eq for core::range::Range<Idx>
where Idx: Eq,

impl<Idx> Eq for core::range::RangeFrom<Idx>
where Idx: Eq,

impl<Idx> Eq for core::range::RangeInclusive<Idx>
where Idx: Eq,

impl<Inner> Eq for Frozen<Inner>
where Inner: Eq + Mutability,

impl<K, V, A> Eq for BTreeMap<K, V, A>
where K: Eq, V: Eq, A: Allocator + Clone,

impl<K, V, S> Eq for HashMap<K, V, S>
where K: Eq + Hash, V: Eq, S: BuildHasher,

impl<M, T> Eq for Address<M, T>
where M: Mutability,

impl<M, T, O> Eq for BitRef<'_, M, T, O>
where M: Mutability, T: BitStore, O: BitOrder,