devela::_core::cmp

Trait Eq

1.6.0 · 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 VarError

impl Eq for devela::_dep::_std::io::SeekFrom

impl Eq for devela::_dep::_std::net::Shutdown

impl Eq for BacktraceStyle

impl Eq for RecvTimeoutError

impl Eq for TryRecvError

impl Eq for CollectionAllocErr

impl Eq for CheckedCastError

impl Eq for PodCastError

impl Eq for devela::_dep::crossterm::event::Event

impl Eq for devela::_dep::crossterm::event::KeyCode

impl Eq for KeyEventKind

impl Eq for MediaKeyCode

impl Eq for ModifierKeyCode

impl Eq for devela::_dep::crossterm::event::MouseButton

impl Eq for MouseEventKind

impl Eq for Attribute

impl Eq for Color

impl Eq for Colored

impl Eq for ClearType

impl Eq for devela::_dep::hashbrown::TryReserveError

impl Eq for Era

impl Eq for devela::_dep::jiff::civil::Weekday

impl Eq for RoundMode

impl Eq for Unit

impl Eq for Meridiem

impl Eq for PiecesOffset

impl Eq for AmbiguousOffset

impl Eq for Dst

impl Eq for EqFilterKind

impl Eq for WhenToStart

impl Eq for PlaybackState

impl Eq for TrackPlaybackState

impl Eq for devela::_dep::log::Level

impl Eq for devela::_dep::log::LevelFilter

impl Eq for ConnectErrorKind

impl Eq for Ignore

impl Eq for PortInfoError

impl Eq for devela::_dep::midir::SendError

impl Eq for BlendFactor

impl Eq for BlendValue

impl Eq for Comparison

impl Eq for CullFace

impl Eq for CursorIcon

impl Eq for Equation

impl Eq for FrontFaceOrder

impl Eq for devela::_dep::miniquad::KeyCode

impl Eq for devela::_dep::miniquad::MouseButton

impl Eq for RawId

impl Eq for StencilOp

impl Eq for TextureAccess

impl Eq for TextureFormat

impl Eq for TextureWrap

impl Eq for TouchPhase

impl Eq for IOURING_OP

impl Eq for perf_event_sample_format_t

impl Eq for ElementType

impl Eq for PyGILState_STATE

impl Eq for PySendResult

impl Eq for _PyStatus_TYPE

impl Eq for Associativity

impl Eq for CacheType

impl Eq for DatType

impl Eq for ExtendedRegisterStateLocation

impl Eq for ExtendedRegisterType

impl Eq for Hypervisor

impl Eq for TopologyType

impl Eq for Yield

impl Eq for Panic

impl Eq for ArchivedIpAddr

impl Eq for ArchivedSocketAddr

impl Eq for BufferSize

impl Eq for HostId

impl Eq for SampleFormat

Trait Eq

§How can I implement `Eq`?