all_observer_lint 0.4.0

Official lint rules and automated fixes for safe, predictable, and efficient development with all_observer.

all_observer_lint

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Official lint rules for building safer Flutter and Dart apps with all_observer.

Leia em português

all_observer_lint helps catch common reactive mistakes directly in your IDE: state created inside build, effects registered on every rebuild, invalid watch(context) usage, impure Computed callbacks, and reactive resources that were not disposed.

It is a development-only package. It does not change your app runtime.

Install

Add both packages as development dependencies:

dart pub add --dev custom_lint all_observer_lint

For Flutter projects:

flutter pub add --dev custom_lint all_observer_lint

Your pubspec.yaml should contain:

dev_dependencies:
  custom_lint: ^0.8.0
  all_observer_lint: ^0.4.0

custom_lint is required because it is the analyzer runner that loads custom lint plugins. all_observer_lint provides the rules.

Configure

In analysis_options.yaml, use the recommended preset:

include: package:all_observer_lint/recommended.yaml

That preset enables the custom_lint analyzer plugin and the recommended rule set.

To show diagnostics in Brazilian Portuguese:

include: package:all_observer_lint/recommended.yaml

custom_lint:
  rules:
    - all_observer:
      language: pt-BR

Migrating from 0.3.x

The package installation command did not change, but custom options now use the custom_lint.rules configuration shape. If you previously configured Portuguese diagnostics with a top-level all_observer: key, move that option under custom_lint.rules as shown above.

Run

Use your normal analyzer workflow:

dart analyze

Or run the custom lint runner directly:

dart run custom_lint

In Flutter projects:

flutter analyze
dart run custom_lint

Most IDEs show the diagnostics automatically after pub get.

Example

This code creates reactive state every time the widget rebuilds:

Widget build(BuildContext context) {
  final count = 0.obs;
  return Text('${count.value}');
}

all_observer_lint reports:

warning: Avoid creating reactive state inside build. The resource will be
recreated whenever the widget rebuilds. Move it to a State field, initState,
controller, view model, or another lifecycle-managed object.

Move the state to a lifecycle-managed place:

class _CounterPageState extends State<CounterPage> {
  final count = 0.obs;

  @override
  Widget build(BuildContext context) {
    return Observer(() => Text('${count.value}'));
  }
}

Quick Fixes

Some rules provide IDE quick fixes. For example, dispose_reactive_resources can add a missing dispose() call:

class _SearchPageState extends State<SearchPage> {
  late final worker = debounce(query, onSearch);

  @override
  void dispose() {
    worker.dispose();
    super.dispose();
  }
}

Presets

Preset	Use when
recommended.yaml	You want the default rule set for everyday projects.
strict.yaml	You also want experimental suggestions for cleaner reactive design.
all.yaml	You want to try every available rule.

Rules

Rule	What it catches
avoid_reactive_creation_in_build	Observable, .obs, Computed, ObservableFuture, or ObservableStream created inside rebuild scopes.
avoid_effect_creation_in_build	effect, ever, once, debounce, or interval registered inside rebuild scopes.
watch_only_inside_build	watch(context) used outside widget build contexts.
dispose_reactive_resources	Workers/effects/streams stored in fields but not disposed.
avoid_reactive_write_in_computed	Reactive writes inside Computed callbacks.
avoid_set_state_in_computed	setState inside Computed callbacks.
avoid_worker_creation_in_computed	Workers/effects created inside Computed callbacks.
avoid_io_in_computed	await or obvious dart:io work inside Computed callbacks.
avoid_observable_write_during_observer_build	Reactive writes while an Observer is building.
self_referencing_computed	A Computed value directly reading its own .value.
prefer_computed_for_derived_state	Manual derived state that could be a Computed.
prefer_batch_for_multiple_related_writes	Related reactive writes that may benefit from batch.
prefer_assign_all_for_reactive_list_replace	ObservableList.clear() followed by add/addAll; prefer assign/assignAll.
unused_reactive_state	Private reactive fields or top-level variables that are never used in the same file.
unobserved_reactive_read_in_build	Reactive .value reads rendered in build without Observer or watch(context).

More Documentation

• Example app
• Architecture and why custom_lint is required
• Known limitations and future rules
• False positive policy

License

MIT. See LICENSE.