wasmer_types::lib::std::cmp

Trait Eq

1.0.0 · source

pub trait Eq: PartialEq { }

Available on crate feature std only.

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 RelocationKind

impl Eq for RelocationTarget

impl Eq for CustomSectionProtection

impl Eq for Symbol

impl Eq for CpuFeature

impl Eq for CompiledFunctionUnwindInfo

impl Eq for Aarch64Architecture

impl Eq for Architecture

impl Eq for BinaryFormat

impl Eq for CallingConvention

impl Eq for Endianness

impl Eq for Environment

impl Eq for ExportIndex

impl Eq for ExternType

impl Eq for HashAlgorithm

impl Eq for ImportIndex

impl Eq for LibCall

impl Eq for MemoryStyle

impl Eq for ModuleHash

impl Eq for Mutability

impl Eq for OperatingSystem

impl Eq for PointerWidth

impl Eq for TableStyle

impl Eq for TrapCode

impl Eq for Type

impl Eq for Vendor

impl Eq for MemoryError

impl Eq for Infallible

impl Eq for wasmer_types::lib::std::fmt::Alignment

impl Eq for wasmer_types::lib::std::sync::atomic::Ordering

impl Eq for RecvTimeoutError

impl Eq for TryRecvError

impl Eq for wasmer_types::lib::std::cmp::Ordering

impl Eq for TryReserveErrorKind

impl Eq for AsciiChar

impl Eq for IpAddr

impl Eq for Ipv6MulticastScope

impl Eq for SocketAddr

impl Eq for FpCategory

impl Eq for IntErrorKind

impl Eq for SearchStep

impl Eq for BacktraceStatus

impl Eq for VarError

impl Eq for SeekFrom

impl Eq for ErrorKind

impl Eq for Shutdown

impl Eq for BacktraceStyle

impl Eq for hashbrown::TryReserveError

impl Eq for hashbrown::TryReserveError

impl Eq for Panic

impl Eq for ArchivedIpAddr

impl Eq for ArchivedSocketAddr

impl Eq for CDataModel

impl Eq for Size

impl Eq for ParseError

impl Eq for ArmArchitecture

impl Eq for CustomVendor

impl Eq for Mips32Architecture

impl Eq for Mips64Architecture

impl Eq for Riscv32Architecture

impl Eq for Riscv64Architecture

impl Eq for X86_32Architecture

impl Eq for bool

impl Eq for char

impl Eq for i8

impl Eq for i16

impl Eq for i32

impl Eq for i64

impl Eq for i128

impl Eq for isize

impl Eq for !

impl Eq for str

impl Eq for u8

impl Eq for u16

impl Eq for u32

Trait Eq

§How can I implement `Eq`?