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.

Eq

Trait Eq Copy item path

§Derivable

§How can I implement Eq?

Dyn Compatibility§

Implementors§

impl Eq for CreationStrategy

impl Eq for AbortReason

impl Eq for AccessControllerError

impl Eq for AccessControllerPartitionOffset

impl Eq for AccessRule

impl Eq for AccountLockerPartitionOffset

impl Eq for AccountPartitionOffset

impl Eq for Actor

impl Eq for AddressBech32DecodeError

impl Eq for AddressBech32EncodeError

impl Eq for AlignerExecutionMode

impl Eq for AlignerFolderMode

impl Eq for AllowedIds

impl Eq for AlwaysVisibleGlobalNodesVersion

impl Eq for AnyTransaction

impl Eq for ApplicationError

impl Eq for AttachedModuleId

impl Eq for AuthError

impl Eq for AuthZoneError

impl Eq for AuthZoneField

impl Eq for BalanceChange

impl Eq for BasicRequirement

impl Eq for BatchPartitionStateUpdate

impl Eq for BlueprintPartitionType

impl Eq for BlueprintPayloadDef

impl Eq for BlueprintPayloadIdentifier

impl Eq for BlueprintType

impl Eq for BootLoaderField

impl Eq for BootloadingError

impl Eq for BucketError

impl Eq for BucketSnapshot

impl Eq for CallFrameDrainSubstatesError

impl Eq for CallFrameError

impl Eq for CallFrameRemoveSubstateError

impl Eq for CallFrameScanKeysError

impl Eq for CallFrameScanSortedSubstatesError

impl Eq for CallFrameSetSubstateError

impl Eq for CannotGlobalizeError

impl Eq for ChildNames

impl Eq for CloseSubstateError

impl Eq for ComponentField

impl Eq for ComponentRoyaltyPartitionOffset

impl Eq for ComposeProofError

impl Eq for CompositeRequirement

impl Eq for ConsensusManagerCollection

impl Eq for ConsensusManagerConfigurationVersions

impl Eq for ConsensusManagerCurrentProposalStatisticVersions

impl Eq for ConsensusManagerCurrentValidatorSetVersions

impl Eq for ConsensusManagerError

impl Eq for ConsensusManagerFeature

impl Eq for ConsensusManagerField

impl Eq for ConsensusManagerPartitionOffset

impl Eq for ConsensusManagerProposerMilliTimestampVersions

impl Eq for ConsensusManagerProposerMinuteTimestampVersions

impl Eq for ConsensusManagerRegisteredValidatorByStakeVersions

impl Eq for ConsensusManagerStateVersions

impl Eq for ConsensusManagerValidatorRewardsVersions

impl Eq for ContentValidationError

impl Eq for CostingError

impl Eq for CreateFrameError

impl Eq for CreateNodeError

impl Eq for CreateObjectError

impl Eq for CurveType

impl Eq for DatabaseUpdate

impl Eq for DateTimeError

impl Eq for DecodeError

impl Eq for DecryptorsByCurve

impl Eq for DecryptorsByCurveV2

impl Eq for DefaultDepositRule

impl Eq for DropNodeError

impl Eq for Emitter

impl Eq for EncodeError

impl Eq for scrypto_test::prelude::EntityType

impl Eq for EventError

Trait Eq

§How can I implement `Eq`?