Flutter linter rules?

Overview

Flutter linter rules in

analysis_options.yaml

Setup

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# analysis_options.yaml (project root)
include: package:flutter_lints/flutter.yaml  # Flutter's recommended set

analyzer:
  strong-mode:
    implicit-casts: false
    implicit-dynamic: false
  errors:
    missing_required_param: error
    missing_return: error

linter:
  rules:
    # Style rules
    - prefer_const_constructors
    - prefer_const_declarations
    - sort_child_properties_last
    - always_use_package_imports

    # Bug prevention
    - avoid_print
    - cancel_subscriptions
    - close_sinks
    - unawaited_futures

    # Null safety
    - avoid_null_checks_in_equality_operators

    # Performance
    - avoid_unnecessary_containers
    - sized_box_for_whitespace

Common Linter Rules

Performance Rules

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// avoid_unnecessary_containers
// ❌
Container(child: Text('Hello'));

// ✅
Text('Hello'); // No Container if no decoration

// sized_box_for_whitespace
// ❌
Container(height: 16);
// ✅
SizedBox(height: 16);

Code Quality Rules

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// prefer_const_constructors
// ❌ — runtime allocation
Text('Hello');
// ✅ — compile-time, reused
const Text('Hello');

// avoid_print (use debugPrint or logger)
// ❌
print('Debug info');
// ✅
debugPrint('Debug info');

Null Safety Rules

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// prefer_if_null_operators
// ❌
final name = user != null ? user.name : 'Guest';
// ✅
final name = user?.name ?? 'Guest';

Popular Rule Packages

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# pubspec.yaml
dev_dependencies:
  flutter_lints: ^3.0.0       # Flutter's default (recommended)
  very_good_analysis: ^5.1.0  # Strict rules (Very Good Ventures)
  lint: ^2.1.2                 # Community rules

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# Include a predefined set
include: package:very_good_analysis/analysis_options.yaml

Common Rules Reference

prefer_const_constructors

avoid_print

cancel_subscriptions

close_sinks

unawaited_futures

sort_child_properties_last

child:

prefer_single_quotes

'

"

always_declare_return_types

Best Practice: Start with

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package:flutter_lints/flutter.yaml

and add rules incrementally. Run

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dart analyze

in CI to enforce rules on every PR.