dart-rules

Dart/Flutter Rules

These rules come from app/rules/dart/ in ai-toolkit. They cover the project's standards for coding style, frameworks, patterns, security, and testing in Dart/Flutter. Apply them when writing or reviewing Dart/Flutter code.

Dart Coding Style

Naming

• PascalCase: classes, enums, typedefs, extensions, mixins.
• camelCase: variables, functions, methods, parameters, named constants.
• snake_case: libraries, packages, directories, source files.
• UPPER_SNAKE: not used in Dart. Use camelCase for constants.
• Prefix private members with _: _internalState, _helper().

Null Safety

• Enable sound null safety (default since Dart 2.12).
• Use ? types only when null is semantically meaningful.
• Use ! operator sparingly. Prefer null checks or ?? fallback.
• Use late keyword only when initialization is guaranteed before access.
• Use required keyword for mandatory named parameters.

Classes

• Use const constructors for immutable classes.
• Use factory constructors for caching, subtype selection, or validation.
• Use named constructors for clarity: Point.fromJson(json).
• Use final fields for immutable properties.
• Use @immutable annotation on classes that should be immutable.

Functions

• Use named parameters for functions with >2 parameters.
• Use required for mandatory named parameters.
• Use default values for optional parameters.
• Use fat arrow (=>) for single-expression functions.
• Always specify return types for public functions.

Collections

• Use collection literals: [], {}, <String, int>{}.
• Use if and for inside collection literals for conditional/iterative building.
• Use spread operator: [...list1, ...list2].
• Use whereType<T>() for type-safe filtering.
• Prefer const collections when values are known at compile time.

Async

• Use async/await for all asynchronous operations.
• Return Future<T> from async functions. Never return void.
• Use Stream<T> for continuous data (events, real-time updates).
• Use Future.wait() for concurrent independent operations.
• Use Completer<T> only when wrapping callback-based APIs.