Trait Eq

1.0.0 · Source

pub trait Eq: PartialEq { }

Expand description

Trait for comparisons corresponding to equivalence relations.

The primary difference to PartialEq is the additional requirement for reflexivity. A type that implements PartialEq guarantees that for all a, b and c:

symmetric: a == b implies b == a and a != b implies !(a == b)
transitive: a == b and b == c implies a == c

Eq, which builds on top of PartialEq also implies:

reflexive: a == a

This property cannot be checked by the compiler, and therefore Eq is a trait without 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.

Floating point types such as f32 and f64 implement only PartialEq but not Eq because NaN != NaN.

§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 extra 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 {}

Dyn Compatibility§

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Trait EqCopy item path

§Derivable

§How can I implement Eq?

Dyn Compatibility§

Implementors§

impl Eq for TryReserveErrorKind

impl Eq for AsciiChar

impl Eq for core::cmp::Ordering

impl Eq for Infallible

impl Eq for FromBytesWithNulError

impl Eq for core::fmt::Alignment

impl Eq for DebugAsHex

impl Eq for Sign

impl Eq for AtomicOrdering

impl Eq for IpAddr

impl Eq for Ipv6MulticastScope

impl Eq for SocketAddr

impl Eq for FpCategory

impl Eq for IntErrorKind

impl Eq for GetDisjointMutError

impl Eq for core::sync::atomic::Ordering

impl Eq for BacktraceStatus

impl Eq for VarError

impl Eq for SeekFrom

impl Eq for std::io::error::ErrorKind

impl Eq for Shutdown

impl Eq for BacktraceStyle

impl Eq for RecvTimeoutError

impl Eq for TryRecvError

impl Eq for arbitrary::error::Error

impl Eq for base64::alphabet::ParseAlphabetError

impl Eq for base64::alphabet::ParseAlphabetError

impl Eq for base64::decode::DecodeError

impl Eq for base64::decode::DecodeError

impl Eq for base64::decode::DecodeSliceError

impl Eq for base64::decode::DecodeSliceError

impl Eq for base64::encode::EncodeSliceError

impl Eq for base64::encode::EncodeSliceError

impl Eq for base64::engine::DecodePaddingMode

impl Eq for base64::engine::DecodePaddingMode

impl Eq for borsh::nostd_io::ErrorKind

impl Eq for byte_slice_cast::Error

impl Eq for cosmos_sdk_proto::cosmos::gov::v1::ProposalStatus

impl Eq for cosmos_sdk_proto::cosmos::gov::v1::VoteOption

impl Eq for cosmos_sdk_proto::cosmos::gov::v1beta1::ProposalStatus

impl Eq for cosmos_sdk_proto::cosmos::gov::v1beta1::VoteOption

impl Eq for AuthorizationType

impl Eq for BondStatus

impl Eq for Infraction

impl Eq for SignMode

impl Eq for BroadcastMode

impl Eq for OrderBy

impl Eq for ibc_proto::ibc::applications::interchain_accounts::v1::Type

impl Eq for Order

impl Eq for ResponseResultType

impl Eq for ibc_proto::ibc::core::channel::v1::State

impl Eq for ibc_proto::ibc::core::connection::v1::State

impl Eq for ConsumerPhase

impl Eq for ConsumerPacketDataType

impl Eq for InfractionType

impl Eq for HashOp

impl Eq for LengthOp

impl Eq for MetaForm

impl Eq for PortableForm

impl Eq for TypeDefPrimitive

impl Eq for PathError

impl Eq for InstanceType

impl Eq for Category

impl Eq for Value

impl Eq for subtle_encoding::error::Error

impl Eq for tendermint_proto::tendermint::v0_34::abci::CheckTxType

impl Eq for EvidenceType

impl Eq for tendermint_proto::tendermint::v0_34::abci::response_apply_snapshot_chunk::Result

impl Eq for tendermint_proto::tendermint::v0_34::abci::response_offer_snapshot::Result

impl Eq for tendermint_proto::tendermint::v0_34::privval::Errors

impl Eq for tendermint_proto::tendermint::v0_34::types::BlockIdFlag

impl Eq for tendermint_proto::tendermint::v0_34::types::SignedMsgType

impl Eq for tendermint_proto::tendermint::v0_37::abci::CheckTxType

impl Eq for tendermint_proto::tendermint::v0_37::abci::MisbehaviorType

impl Eq for tendermint_proto::tendermint::v0_37::abci::response_apply_snapshot_chunk::Result

Trait Eq

§How can I implement `Eq`?