rustmax::core::cmp

Trait Eq

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
transitive: a == b and b == c implies a == c
consistent: a != b if and only if !(a == b)

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".

Implementors§

1.100.0 (const: unstable) · Source§

impl Eq for !

1.0.0 (const: unstable) · Source§

Eq

Trait Eq Copy item path

§Derivable

§How can I implement Eq?

Dyn Compatibility§

Implementors§

impl Eq for !

impl Eq for ()

impl Eq for ASN1_ITEM_st

impl Eq for ASN1_TEMPLATE_st

impl Eq for ATerm

impl Eq for AUTHORITY_KEYID_st

impl Eq for rustmax::core::mem::type_info::Abi

impl Eq for rustmax::bindgen::Abi

impl Eq for syn::ty::Abi

impl Eq for Aborted

impl Eq for Abstract

impl Eq for Access

impl Eq for AccessError

impl Eq for AccessFlags

impl Eq for AccessKind

impl Eq for AccessMode

impl Eq for anstyle_parse::state::definitions::Action

impl Eq for bzip2::mem::Action

impl Eq for Adam7Info

impl Eq for Adam7Variant

impl Eq for AdditionError

impl Eq for rustmax::core::net::AddrParseError

impl Eq for ipnet::parser::AddrParseError

impl Eq for rustls_pki_types::server_name::AddrParseError

impl Eq for Advice

impl Eq for AesMode

impl Eq for AesSalt

impl Eq for AhoCorasickKind

impl Eq for AlertDescription

impl Eq for AlertType

impl Eq for aws_lc_rs::aead::quic::Algorithm

impl Eq for aws_lc_rs::aead::Algorithm

impl Eq for aws_lc_rs::agreement::Algorithm

impl Eq for aws_lc_rs::cmac::Algorithm

impl Eq for aws_lc_rs::digest::Algorithm

impl Eq for aws_lc_rs::hkdf::Algorithm

impl Eq for aws_lc_rs::hmac::Algorithm

impl Eq for aws_lc_rs::pbkdf2::Algorithm

impl Eq for aws_lc_rs::cipher::Algorithm

impl Eq for AlgorithmId

impl Eq for AlgorithmIdentifier

impl Eq for AliasVariation

impl Eq for rustmax::core::mem::Alignment

impl Eq for rustmax::core::fmt::Alignment

impl Eq for console::utils::Alignment

impl Eq for AllocErr

impl Eq for rustmax::core::alloc::AllocError

impl Eq for zerocopy::error::AllocError

impl Eq for AlphaColorMode

impl Eq for base64::alphabet::Alphabet

impl Eq for rustmax::base64::alphabet::Alphabet

impl Eq for Alternation

impl Eq for rustmax::jiff::tz::AmbiguousOffset

impl Eq for rustmax::jiff::__jcore::tz::AmbiguousOffset

impl Eq for rustmax::jiff::tz::AmbiguousTimestamp

impl Eq for rustmax::jiff::__jcore::tz::AmbiguousTimestamp

impl Eq for AmbiguousZoned

impl Eq for Anchor

impl Eq for regex_automata::util::search::Anchored

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

impl Eq for And

impl Eq for AndAnd

impl Eq for AndEq

impl Eq for AngleBracketedGenericArguments

impl Eq for Ansi256Color

impl Eq for AnsiColor

impl Eq for AnyDelimiterCodec

impl Eq for AnyExtension

impl Eq for ArchiveOffset

impl Eq for Arg

impl Eq for ArgCursor

impl Eq for ArgGroup

impl Eq for ArgMatches

impl Eq for ArgPredicate

Trait Eq

§How can I implement `Eq`?