Trait Eq

1.55.0 (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 ComputationStatus

impl Eq for ConvergenceResult

impl Eq for CoordinateSystem

impl Eq for TensorType

impl Eq for DagOp

impl Eq for Expr

impl Eq for PathType

impl Eq for CurvePoint

impl Eq for LinearOperator

impl Eq for Literal

impl Eq for ExtremumType

impl Eq for PDEType

impl Eq for CheckpointingFrequency

impl Eq for TerminationReason

impl Eq for TerminationStatus

impl Eq for ObserverMode

impl Eq for rssn::prelude::argmin::distr::BernoulliError

impl Eq for rssn::prelude::argmin::distr::uniform::Error

impl Eq for rssn::prelude::argmin::seq::WeightError

impl Eq for rssn::prelude::bincode::config::Endianness

impl Eq for IntEncoding

impl Eq for AllowedEnumVariants

impl Eq for IntegerType

impl Eq for rssn::prelude::nalgebra::TAffine

impl Eq for rssn::prelude::nalgebra::TGeneral

impl Eq for rssn::prelude::nalgebra::TProjective

impl Eq for Order

impl Eq for SliceInfoElem

impl Eq for rssn::prelude::num::Sign

impl Eq for rssn::prelude::rand::distributions::BernoulliError

impl Eq for WeightedError

impl Eq for FftDirection

impl Eq for CompressedStorage

impl Eq for FillInReduction

impl Eq for PermutationCheck

impl Eq for SymmetryCheck

impl Eq for LinalgError

impl Eq for SprsError

impl Eq for StructureError

impl Eq for StructureErrorKind

impl Eq for SymmetryMode

impl Eq for NumKind

impl Eq for ThreadingStrategy

impl Eq for rssn::prelude::statrs::distribution::BetaError

impl Eq for BinomialError

impl Eq for CategoricalError

impl Eq for CauchyError

impl Eq for ChiError

impl Eq for DiracError

impl Eq for DirichletError

impl Eq for DiscreteUniformError

impl Eq for ExpError

impl Eq for FisherSnedecorError

impl Eq for GammaError

impl Eq for GeometricError

impl Eq for GumbelError

impl Eq for HypergeometricError

impl Eq for InverseGammaError

impl Eq for LaplaceError

impl Eq for LogNormalError

impl Eq for MultinomialError

impl Eq for MultivariateNormalError

impl Eq for MultivariateStudentError

impl Eq for NegativeBinomialError

impl Eq for NormalError

impl Eq for ParetoError

impl Eq for PoissonError

impl Eq for StudentsTError

impl Eq for rssn::prelude::statrs::distribution::TriangularError

impl Eq for UniformError

impl Eq for WeibullError

impl Eq for BetaFuncError

impl Eq for GammaFuncError

impl Eq for FishersExactTestError

Trait Eq

§How can I implement `Eq`?