Dart Code Style and Best Practices

Naming Conventions

// Classes, enums, typedefs — UpperCamelCase:
class UserProfile {}
enum AccountStatus { active, inactive }
typedef EventHandler = void Function(String);

// Variables, functions, parameters — lowerCamelCase:
var userName = 'Alice';
int calculateTotal(int price, int quantity) => price * quantity;

// Constants — lowerCamelCase (not SCREAMING_SNAKE):
const maxRetries = 3;
const defaultTimeout = Duration(seconds: 30);

// Private members — prefix with underscore:
class _InternalHelper {}
int _privateCounter = 0;

// Libraries and packages — lowercase_with_underscores:
// my_library.dart, user_service.dart

// Booleans — use positive names:
bool isActive = true;   // ✅
bool hasPermission = true;  // ✅
bool notDisabled = true; // ❌ (negative name)

Formatting

# Format all files:
dart format .

# Check without modifying:
dart format --output=none --set-exit-if-changed .

# Dart uses 2-space indentation
# Max line length: 80 characters (soft limit)
# Trailing commas in multi-line collections preserve formatting:

// Good — trailing commas keep items on separate lines after formatting:
var config = Config(
  host: 'localhost',
  port: 5432,
  database: 'mydb',
  ssl: true,   // ← trailing comma
);

// Good — short enough to be on one line:
var point = Point(x: 10, y: 20);

Effective Dart Guidelines

// PREFER final for variables that don't change:
final userName = 'Alice';   // ✅
var userName = 'Alice';     // ❌ (misleads — looks mutable)

// USE type inference — don't add obvious types:
var count = 0;              // ✅
int count = 0;              // ❌ (redundant)
List<User> users = [];     // ✅ (type adds info)

// AVOID using dynamic:
dynamic value = 'text';    // ❌
Object? value = 'text';    // ✅ (type-safe)

// PREFER expression bodies for simple functions:
String greet(String name) => 'Hello, $name!';   // ✅
String greet(String name) { return 'Hello, $name!'; } // ❌

// USE ?? for null defaults:
String display = value ?? 'N/A';  // ✅
String display = value != null ? value : 'N/A'; // ❌

// USE collection if/for:
var items = [
  'base',
  if (isAdmin) 'admin-panel',
  for (var tag in tags) 'tag:$tag',
];

Lints and Analysis

# analysis_options.yaml
include: package:lints/recommended.yaml

linter:
  rules:
    prefer_final_locals: true
    avoid_print: true
    prefer_const_constructors: true
    sort_constructors_first: true

# Run analysis:
dart analyze

🧠 Quiz

Summary

Follow Effective Dart: use UpperCamelCase for types, lowerCamelCase for variables and functions, and _prefix for private members. Prefer final over var, use type inference, and write expression bodies for simple functions. Format with dart format and check with dart analyze. Add an analysis_options.yaml with recommended lints.