Trait Eq

1.0.0 (const: unstable) · 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.

Eq

Trait Eq Copy 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 SimdAlign

impl Eq for IpAddr

impl Eq for Ipv6MulticastScope

impl Eq for SocketAddr

impl Eq for FpCategory

impl Eq for IntErrorKind

impl Eq for core::slice::GetDisjointMutError

impl Eq for SearchStep

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 std::sync::mpsc::TryRecvError

impl Eq for Colons

impl Eq for Fixed

impl Eq for Numeric

impl Eq for chrono::format::OffsetPrecision

impl Eq for Pad

impl Eq for ParseErrorKind

impl Eq for SecondsFormat

impl Eq for chrono::month::Month

impl Eq for RoundingError

impl Eq for chrono::weekday::Weekday

impl Eq for subtle_encoding::error::Error

impl Eq for tenderdash_proto::tenderdash_grpc::abci::CheckTxType

impl Eq for tenderdash_proto::tenderdash_grpc::abci::MisbehaviorType

impl Eq for tenderdash_proto::tenderdash_grpc::abci::response_apply_snapshot_chunk::Result

impl Eq for tenderdash_proto::tenderdash_grpc::abci::response_offer_snapshot::Result

impl Eq for tenderdash_proto::tenderdash_grpc::abci::response_process_proposal::ProposalStatus

impl Eq for tenderdash_proto::tenderdash_grpc::abci::response_verify_vote_extension::VerifyStatus

impl Eq for tenderdash_proto::tenderdash_grpc::abci::tx_record::TxAction

impl Eq for tenderdash_proto::tenderdash_grpc::crypto::public_key::Sum

impl Eq for tenderdash_proto::tenderdash_grpc::types::BlockIdFlag

impl Eq for tenderdash_proto::tenderdash_grpc::types::SignedMsgType

impl Eq for tenderdash_proto::tenderdash_grpc::types::VoteExtensionType

impl Eq for tenderdash_proto::tenderdash_grpc::types::version_params::ConsensusVersion

impl Eq for tenderdash_proto::tenderdash_grpc_client::abci::CheckTxType

impl Eq for tenderdash_proto::tenderdash_grpc_client::abci::MisbehaviorType

impl Eq for tenderdash_proto::tenderdash_grpc_client::abci::response_apply_snapshot_chunk::Result

impl Eq for tenderdash_proto::tenderdash_grpc_client::abci::response_offer_snapshot::Result

impl Eq for tenderdash_proto::tenderdash_grpc_client::abci::response_process_proposal::ProposalStatus

impl Eq for tenderdash_proto::tenderdash_grpc_client::abci::response_verify_vote_extension::VerifyStatus

impl Eq for tenderdash_proto::tenderdash_grpc_client::abci::tx_record::TxAction

impl Eq for tenderdash_proto::tenderdash_grpc_client::crypto::public_key::Sum

impl Eq for tenderdash_proto::tenderdash_grpc_client::types::BlockIdFlag

impl Eq for tenderdash_proto::tenderdash_grpc_client::types::SignedMsgType

impl Eq for tenderdash_proto::tenderdash_grpc_client::types::VoteExtensionType

impl Eq for tenderdash_proto::tenderdash_grpc_client::types::version_params::ConsensusVersion

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

Trait Eq

§How can I implement `Eq`?