update

dart_ex_1/ex_2.dart

@@ -1,96 +1,122 @@
-// A Mixin: Adds specific behavior without being a parent class
 mixin Connectable {
   bool isConnected = false;
   void toggleConnection() => isConnected = !isConnected;
 }
 
 abstract class SmartDevice {
-  final String id;        // Final: Set once
+  final String id;
-  String _name;           // Private field (starts with _)
+  String _name;
   bool _powerStatus = false;
+  bool _auto_on_off = false;
 
-  static const String brand = "GeminiHome"; // Static: Shared by all instances
+  static const String brand = "GeminiHome";
 
-  // 1. Generative Constructor
+  // 1. Standard Constructor with named parameters
-  SmartDevice(this.id, this._name);
+  SmartDevice({required this.id, required String name}) : _name = name;
 
-  // 2. Named Constructor
+  // 2. Named Constructor: Preset for Office use
-  SmartDevice.temp(this.id) : _name = "Unknown Device";
+  SmartDevice.office({required this.id})
+      : _name = "Office Desk Lamp",
+        _auto_on_off = true;
 
-  // 3. Factory Constructor: Decides which subclass to return
+  // 3. Named Constructor: Preset for Eco mode
-  factory SmartDevice.create(String type, String id, String name) {
+  SmartDevice.eco({required this.id})
-    if (type == 'light') return SmartLight(id, name);
+      : _name = "Eco Saver Unit",
-    return SmartSpeaker(id, name);
+        _powerStatus = false,
+        _auto_on_off = true;
+
+  // 4. Factory Constructor using named parameters
+  factory SmartDevice.create({
+    required String type,
+    required String id,
+    required String name,
+  }) {
+    if (type == 'light') return SmartLight(id: id, name: name);
+    return SmartSpeaker(id: id, name: name);
+  }
+
+  // Specialized factory for the Office preset
+  factory SmartDevice.createOffice({required String id}) {
+    return SmartLight.office(id: id);
   }
 
-  // Getter and Setter
   String get name => _name;
   set name(String value) => _name = value.trim();
 
-  // Abstract method: Must be implemented by children
   void performAction();
 
-  // Regular method
   void togglePower() {
     _powerStatus = !_powerStatus;
-    print('$_name is now ${_powerStatus ? "ON" : "OFF"}');
+    print('$_name is now ${_powerStatus ? "ON" : "OFF"} (Auto-mode: $_auto_on_off)');
   }
 }
 
-
-
 class SmartLight extends SmartDevice {
   int brightness = 100;
 
-  // Uses 'super' to pass data to the parent constructor
+  // Using 'super' syntax with named parameters
-  SmartLight(super.id, super.name);
+  SmartLight({required super.id, required super.name});
+
+  // Redirecting to parent named constructors
+  SmartLight.office({required String id}) : super.office(id: id);
+  
+  SmartLight.eco({required String id}) : super.eco(id: id);
 
   @override
   void performAction() {
-    print('Adjusting brightness to $brightness%');
+    print('[$_name] Brightness: $brightness%');
   }
 }
 
-
-
-
-// 'with Connectable' adds the toggleConnection() method to this class
 class SmartSpeaker extends SmartDevice with Connectable {
   double volume;
 
-  // 4. Initializer List: Sets volume before the constructor body runs
+  SmartSpeaker({
-  SmartSpeaker(String id, String name, {this.volume = 0.5}) 
+    required String id,
-      : assert(volume >= 0 && volume <= 1.0),
+    required String name,
-        super(id, name);
+    this.volume = 0.5,
-
+  })  : assert(volume >= 0 && volume <= 1.0),
-  // 5. Redirecting Constructor: Forwards to the main constructor
+        super(id: id, name: name);
-  SmartSpeaker.loud(String id, String name) : this(id, name, volume: 1.0);
 
   @override
   void performAction() {
-    print('Playing music at ${volume * 100}% volume. WiFi: $isConnected');
+    print('[$_name] Volume: ${(volume * 100).toInt()}%. Connected: $isConnected');
   }
 }
 
-
-
-
 void main() {
-  // Using the Factory
+  // --- USAGE ---
-  final myLight = SmartDevice.create('light', 'L1', 'Living Room Lamp');
+
+  // 1. Using the 'Office' preset with named ID
+  final workLamp = SmartLight.office(id: 'OFFICE_01');
   
-  // Using the Redirecting Constructor
+  // 2. Using the 'Eco' preset with named ID
-  final partySpeaker = SmartSpeaker.loud('S1', 'Bass Blaster');
+  final ecoLight = SmartLight.eco(id: 'ECO_99');
 
-  myLight.togglePower();     // Parent method
+  // 3. Standard creation using clear labels for ID and Name
-  partySpeaker.toggleConnection(); // Mixin method
+  final customLight = SmartLight(id: 'CUST_01', name: 'My Custom Light');
-  partySpeaker.performAction();    // Overridden method
+
+  // 4. Using the factory with named parameters
+  final speaker = SmartDevice.create(
+    type: 'speaker', 
+    id: 'SPK_01', 
+    name: 'Living Room Bass'
+  );
+
+  print('--- Testing Presets ---');
+  workLamp.performAction();
+  workLamp.togglePower();
+  
+  print('');
+  
+  ecoLight.performAction();
+  ecoLight.togglePower();
+
+  print('');
+  speaker.performAction();
 }
 
 
-
-
-
 // You're absolutely right. Understanding *why* we use these features is more important than just knowing the syntax. Let’s break down the rationale and real-world use cases for the structure I built.
 
 // ---