Trait Eq

1.0.0 (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 VariableKind

impl Eq for ResolvedVariable

impl Eq for datex_core::collections::TryReserveErrorKind

impl Eq for VariableModel

impl Eq for VariableRepresentation

impl Eq for VariableShape

impl Eq for NewScopeType

impl Eq for Assoc

impl Eq for BracketStyle

impl Eq for StatementFormatting

impl Eq for TypeDeclarationFormatting

impl Eq for VariantFormatting

impl Eq for InstructionCode

impl Eq for ArithmeticOperator

impl Eq for ArithmeticUnaryOperator

impl Eq for BitwiseUnaryOperator

impl Eq for LogicalUnaryOperator

impl Eq for ReferenceUnaryOperator

impl Eq for UnaryOperator

impl Eq for InternalSlot

impl Eq for TypeInstructionCode

impl Eq for CoreLibPointerId

impl Eq for InterfacePriority

impl Eq for ComInterfaceState

impl Eq for MediaKind

impl Eq for ParserError

impl Eq for datex_core::parser::lexer::Token

impl Eq for Reference

impl Eq for ReferenceCreationError

impl Eq for ReferenceMutability

impl Eq for ExecutionMode

impl Eq for InvalidProgramError

impl Eq for TypeError

impl Eq for CollectionTypeDefinition

impl Eq for TypeDefinition

impl Eq for StructuralTypeDefinition

impl Eq for CoreValue

impl Eq for CallableBody

impl Eq for CallableKind

impl Eq for Decimal

impl Eq for DecimalTypeVariant

impl Eq for TypedDecimal

impl Eq for EndpointInstance

impl Eq for EndpointType

impl Eq for InvalidEndpointError

impl Eq for NumberParseError

impl Eq for IntegerTypeVariant

impl Eq for TypedInteger

impl Eq for datex_core::values::core_values::map::Map

impl Eq for PointerAddress

impl Eq for ValueContainer

impl Eq for AsciiChar

impl Eq for BacktraceStatus

impl Eq for Infallible

impl Eq for VarError

impl Eq for FromBytesWithNulError

impl Eq for datex_core::stdlib::fmt::Alignment

impl Eq for DebugAsHex

impl Eq for datex_core::stdlib::fmt::Sign

impl Eq for Locality

impl Eq for AtomicOrdering

impl Eq for SimdAlign

impl Eq for datex_core::stdlib::io::ErrorKind

impl Eq for SeekFrom

impl Eq for datex_core::stdlib::net::IpAddr

impl Eq for Ipv6MulticastScope

impl Eq for datex_core::stdlib::net::Shutdown

impl Eq for SocketAddr

impl Eq for FpCategory

impl Eq for IntErrorKind

impl Eq for BacktraceStyle

impl Eq for datex_core::stdlib::slice::GetDisjointMutError

impl Eq for SearchStep

impl Eq for datex_core::stdlib::sync::atomic::Ordering

Trait Eq

§How can I implement `Eq`?