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name: dart-best-practices description: "Dart code quality conventions: naming, const/final/var hierarchy, single quotes, trailing commas, collection idioms, tear-offs, and import organization. Use only for Dart style-focused changes or reviews; never activate for configuration-only lint setup, unrelated feature work, or widget tests." metadata: triggers: files: - "**/*.dart" keywords: - naming - convention - trailing comma - import - tear-off

Dart Best Practices

Priority: P1 (HIGH)

• Scoping:
• No global variables.
• Private globals (if required) must start with _.
• Immutability: Use const > final > var.
• Config: Use --dart-define for secrets. Never hardcode API keys.
• Naming: Follow effective-dart (PascalCase classes, camelCase members).
• Strings: Prefer single quotes; use double quotes only for interpolation needs.
• Trailing Commas: Always use trailing commas for multi-line literals/params.
• Expression Bodies: Prefer => for single-expression functions/getters.
• Collections:
• Use .map, .where, .fold, .any over manual loops when clarity improves.
• Type empty collections (<String>[], <String, User>{}) to avoid dynamic.
• Use collection if/for and spread operators for composable lists/maps.
• Async: Always await futures unless intentionally fire-and-forget.

import 'models/user.dart'; // Good
import 'package:app/models/user.dart'; // Avoid local absolute

Anti-Patterns

• No var for non-obvious types: Use final or explicit type; var only for locally-obvious short scopes.
• No package imports within same package: Use relative imports for intra-package files.
• No top-level mutable state: Encapsulate in class or inject via DI.
• No anonymous lambdas for tear-offs: Prefer list.forEach(doSomething) over anonymous form.