Пример

Give a Dart class value equality with no code generation, so two instances with the same fields are ==, hash the same, and work as Set members and Map keys

sha256:89d2bef982143e36175a1174a40d2ddf617e91bf571cde4cd217db418fbf1a1b

Кейс

Цель

Give a Dart class value equality with no code generation, so two instances with the same fields are ==, hash the same, and work as Set members and Map keys HOW

Пакеты

equatable 2.1.0

Окружение

dart 3

Создан

2026-08-14T20:03:00Z

Контракт

• assert two instances with equal fields are == where the same class without Equatable compares by identity, that their hashCodes agree, that a difference in either field is a difference, and that const canonicalization is what makes the unhelped class look right sometimes
• assert equatable generates no copyWith, so a hand-written one returns an equal-but-not-identical instance and carries untouched fields over, and that the usual null-coalescing body cannot clear a nullable field while a private sentinel default plus identical can
• assert a field left out of props is silently dropped from equality: two orders with different line items are ==, hash the same, collapse to one entry in a Set, and overwrite each other as Map keys with no warning anywhere
• assert a List in props is compared element-wise and in order while a Set and a Map prop are order-insensitive, that a nested Equatable composes through its own ==, and that two nums in props compare and hash across int and double
• assert a rebuilt equal instance is found by Set.contains and as a Map key, but mutating a List prop in place after insertion changes the hashCode, leaves the object unfindable and unremovable inside the Set, and lets the Set accept an equal duplicate
• assert copying that Set does not repair it, because a spread literal and Set.of given another Set carry the stale entry across and Map.of does the same for keys, while routing the elements through a plain Iterable or adding them in a loop rehashes and does repair it
• assert runtimeType is compared before props, so a subclass inheriting props verbatim is not == to its parent in either direction, and an inherited hand-written copyWith downcasts it into an unequal parent instance
• assert toString prints the props under asserts and only the type name when EquatableConfig.stringify is false, and that a per-instance stringify overrides the global setting
• assert Equatable is an abstract mixin class in 2.1.0 so it can be mixed into a class that already extends something, while EquatableMixin still works but is deprecated and is not a subtype of Equatable

Файлы

• csx.json
• lib/value.dart
• pubspec.lock
• pubspec.yaml
• test/contract_test.dart

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Исходный сидер

anonymous

Квитанции проверки

• dart 3 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · pub@1 · 2026-08-14 · ed25519:a2ec939a4c60e243