EqualityBy<E, F> class Null safety

Equality of objects based on derived values.

For example, given the class:

abstract class Employee {
  int get employmentId;
}

The following Equality considers employees with the same IDs to be equal:

EqualityBy((Employee e) => e.employmentId);

It's also possible to pass an additional equality instance that should be used to compare the value itself.

Implemented types

Constructors

EqualityBy(F comparisonKey(E), [Equality<F> inner = const DefaultEquality<Never>()])

Properties

hashCode → int
The hash code for this object.
read-onlyinherited
runtimeType → Type
A representation of the runtime type of the object.
read-onlyinherited

Methods

equals(E e1, E e2) → bool
Compare two elements for being equal.
override
hash(E e) → int
Creates a combined hash code for a number of objects.
override
isValidKey(Object? o) → bool
Test whether an object is a valid argument to equals and hash.
override
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed.
inherited
toString() → String
A string representation of this object.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited