script::dom::bindings::import::module::cmp

Trait Eq

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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 AhoCorasickKind

impl Eq for aho_corasick::packed::api::MatchKind

impl Eq for aho_corasick::util::error::MatchErrorKind

impl Eq for aho_corasick::util::search::Anchored

impl Eq for aho_corasick::util::search::MatchKind

impl Eq for StartKind

impl Eq for allocator_api2::stable::raw_vec::TryReserveErrorKind

impl Eq for TlsProtocolId

impl Eq for AlgorithmId

impl Eq for OperatingMode

impl Eq for KbkdfCtrHmacAlgorithmId

impl Eq for SskdfDigestAlgorithmId

impl Eq for SskdfHmacAlgorithmId

impl Eq for BlockCipherId

impl Eq for KeySize

impl Eq for point_conversion_form_t

impl Eq for MonitoredComponentType

impl Eq for PrintFmt

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 PadType

impl Eq for Blocklist

impl Eq for byte_slice_cast::Error

impl Eq for CheckedCastError

impl Eq for PodCastError

impl Eq for byteorder::BigEndian

impl Eq for byteorder::LittleEndian

impl Eq for Keviyah

impl Eq for StartOfYear

impl Eq for YearType

impl Eq for AlphaTreatment

impl Eq for TexDataType

impl Eq for TexFormat

impl Eq for WebGLFramebufferBindingRequest

impl Eq for WebGLVersion

impl Eq for YAxisTreatment

impl Eq for Colons

impl Eq for Fixed

impl Eq for chrono::format::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 LabelStyle

impl Eq for codespan_reporting::diagnostic::Severity

impl Eq for colored::color::Color

impl Eq for Styles

impl Eq for TraversalDirection

impl Eq for WindowSizeType

impl Eq for CheckResult

impl Eq for Destination

impl Eq for HashAlgorithm

impl Eq for Initiator

impl Eq for InlineCheckType

impl Eq for MatchResult

impl Eq for ParserMetadata

impl Eq for PolicyDisposition

impl Eq for PolicySource

impl Eq for SubresourceIntegrityMetadata

impl Eq for Violates

impl Eq for cookie::draft::SameSite

impl Eq for cookie::expiration::Expiration

impl Eq for cookie::expiration::Expiration

impl Eq for cookie::parse::ParseError

Trait Eq

§How can I implement `Eq`?