Named Constructors

🎯 Mục tiêu: Tạo constructors với tên mô tả.

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💡 Cú pháp

class Point {
  double x, y;

  Point(this.x, this.y);

  // Named constructors
  Point.origin() : x = 0, y = 0;

  Point.fromJson(Map<String, double> json)
      : x = json['x'] ?? 0,
        y = json['y'] ?? 0;
}

var p1 = Point.origin();
var p2 = Point.fromJson({'x': 10, 'y': 20});

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📱 Trong Flutter - Models

class User {
  final String id;
  final String name;
  final String email;

  User({
    required this.id,
    required this.name,
    required this.email,
  });

  User.fromJson(Map<String, dynamic> json)
      : id = json['id'],
        name = json['name'],
        email = json['email'];

  Map<String, dynamic> toJson() => {
    'id': id,
    'name': name,
    'email': email,
  };
}

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✅ Checklist

• Dùng ClassName.name() syntax
• Initializer list với :
• Common: fromJson, fromMap

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