Equals and Hash

This page discusses the operator== (equals) and hashCode of the automatically generated Dart class.

Default

The default for non-freezed classes is field-by-field comparison. For Dart collection fields such as List, Map, and Set, this follows Dart's default collection semantics, i.e. identity equality. You can use #[frb(non_hash, non_eq)] to disable such generated code.

The default for freezed classes: Usually field-by-field comparison (see freezed's doc for more details).

Deep collection equality

Set dart_collection_deep_equality: true in flutter_rust_bridge.yaml, or pass --dart-collection-deep-equality to the codegen command, to generate deep equality and hash code for Dart collection fields in non-freezed classes. This affects List, Map, Set, optional values wrapping those collection types, and generated fixed-size array wrapper classes such as U8Array32.

To opt in for only one non-freezed struct, use #[frb(dart_collection_deep_equality)] on that struct instead of enabling the global option. This does not change the default behavior for other structs in the project. Since generated fixed-size array wrapper classes are shared Dart types, their own operator== and hashCode only change when the global option is enabled.

If you want richer Dart value-class semantics, another option is to use freezed, which can also generate deep equality for collection fields.

Custom (arbitrary)

Arbitrary equals/hash function can also be implemented by using the extra Dart code feature. For example, #[frb(dart_code = "int get hashCode { arbitrary_code_calling_whatever_Rust_and_Dart_things }")].