Trait frame_support::dispatch::Eq

1.0.0 · source ·

pub trait Eq: PartialEq<Self> { }

Expand description

Trait for equality comparisons which are equivalence relations.

This means, that in addition to a == b and a != b being strict inverses, the equality must be (for all a, b and c):

reflexive: a == a;
symmetric: a == b implies b == a; and
transitive: a == b and b == c implies a == c.

This property cannot be checked by the compiler, and therefore Eq implies PartialEq, and has no extra methods.

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 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 {}

Trait frame_support::dispatch::Eq

Derivable

How can I implement Eq?

Implementors§

impl Eq for aho_corasick::ahocorasick::MatchKind

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

impl Eq for PrintFmt

impl Eq for base16ct::error::Error

impl Eq for DecodeError

impl Eq for byte_slice_cast::Error

impl Eq for byteorder::BigEndian

impl Eq for byteorder::LittleEndian

impl Eq for SecondsFormat

impl Eq for Fixed

impl Eq for Numeric

impl Eq for Pad

impl Eq for ParseErrorKind

impl Eq for Month

impl Eq for RoundingError

impl Eq for Weekday

impl Eq for ArrayType

impl Eq for BaseUnresolvedName

impl Eq for BuiltinType

impl Eq for CallOffset

impl Eq for ClassEnumType

impl Eq for CtorDtorName

impl Eq for Decltype

impl Eq for DestructorName

impl Eq for cpp_demangle::ast::Encoding

impl Eq for ExprPrimary

impl Eq for cpp_demangle::ast::Expression

impl Eq for GlobalCtorDtor

impl Eq for LocalName

impl Eq for MangledName

impl Eq for Name

impl Eq for NestedName

impl Eq for OperatorName

impl Eq for cpp_demangle::ast::Prefix

impl Eq for PrefixHandle

impl Eq for RefQualifier

impl Eq for SimpleOperatorName

impl Eq for SpecialName

impl Eq for StandardBuiltinType

impl Eq for Substitution

impl Eq for TemplateArg

impl Eq for TemplateTemplateParamHandle

impl Eq for cpp_demangle::ast::Type

impl Eq for TypeHandle

impl Eq for UnqualifiedName

impl Eq for UnresolvedName

impl Eq for UnresolvedType

impl Eq for UnresolvedTypeHandle

impl Eq for UnscopedName

impl Eq for UnscopedTemplateNameHandle

impl Eq for VectorType

impl Eq for WellKnownComponent

impl Eq for DemangleNodeType

impl Eq for cpp_demangle::error::Error

impl Eq for Reloc

impl Eq for CursorPosition

impl Eq for AtomicRmwOp

impl Eq for FloatCC

impl Eq for IntCC

impl Eq for ValueDef

impl Eq for AnyEntity

impl Eq for ArgumentExtension

impl Eq for ArgumentPurpose

impl Eq for ExternalName

impl Eq for InstructionFormat

impl Eq for Opcode

impl Eq for ResolvedConstraint

impl Eq for LibCall

impl Eq for cranelift_codegen::ir::memflags::Endianness

impl Eq for ExpandedProgramPoint

impl Eq for StackSlotKind

impl Eq for cranelift_codegen::ir::trapcode::TrapCode

impl Eq for CallConv

impl Eq for cranelift_codegen::isa::LookupError

impl Eq for cranelift_codegen::isa::unwind::UnwindInfo

impl Eq for UnwindInst

How can I implement `Eq`?