Equatable

protocol Equatable

Instances of conforming types can be compared for value equality using operators == and !=.

When adopting Equatable, only the == operator is required to be implemented. The standard library provides an implementation for !=.

Inheritance View Protocol Hierarchy →
Import import Swift

Instance Methods

func ==(_:rhs:) Required

Returns true if lhs is equal to rhs.

Equality implies substitutability. When x == y, x and y are interchangeable in any code that only depends on their values.

Class instance identity as distinguished by triple-equals === is notably not part of an instance's value. Exposing other non-value aspects of Equatable types is discouraged, and any that are exposed should be explicitly pointed out in documentation.

Equality is an equivalence relation

  • x == x is true
  • x == y implies y == x
  • x == y and y == z implies x == z

Inequality is the inverse of equality, i.e. !(x == y) iff x != y.

Declaration

func ==(lhs: Self, rhs: Self) -> Bool