mixins in Dart

What are Mixins in Dart?

• A mixin is a class that contains a set of methods and properties that can be used by other classes. It is a way to reuse code across multiple classes. Example : Lets say your desgning a car, whats the common things we see in all cars , like windows, wheels, engine etc and whats the common actions like driving, braking, accelerating. So we can create a class Car which will have all these common properties and behaviors.

How to Declare a Class in Dart?

• In Dart, you can declare a class using the class keyword followed by the class name and a pair of curly braces {} to define the body of the class.

class Car {
  // Properties
  String color;
  String model;
  
  // Method
  void drive() {
    print('The $color $model is driving.');
  }
}

What are Objects in Dart?

• An object is an instance of a class.
• If Class is considered as a blueprint, then object is the actual thing created using that blueprint.
• Continuation of the previous example, once we have the Car class defined, we can create objects (instances) of that class representing specific added features like ai r conditioning, sunroof etc. to the existing car class.

How to Create an Object in Dart?

• You can create an object of a class using the new keyword followed by the class name and parentheses (). However, using new is optional in Dart.

void main() {
  // Creating an object of the Car class
  Car myCar = Car();
  
  // Setting properties
  myCar.color = 'Red';
  myCar.model = 'Toyota';
  
  // Calling method
  myCar.drive(); // Output: The Red Toyota is driving.
}

What is Contructor in Dart?

• A constructor is default method that is called when an object of a class is created.- It is used to initialize the properties of the object.
• In Dart, a constructor has the same name as the class and does not have a return
• It helps to pass the agruments while creating the object.

class Car {
  // Properties
  String color;
  String model;
  
  // Constructor
  Car(this.color, this.model);
  
  // Method
  void drive() {
    print('The $color $model is driving.');
  }
}
void main() {
  // Creating an object of the Car class using constructor
  Car myCar = Car('Blue', 'Honda');
  
  // Calling method
  myCar.drive(); // Output: The Blue Honda is driving.
}

What is Static variable and method in Dart?

• Static variables and methods belong to the class itself rather than to any specific instance (object) of the class.
• You can access static members using the class name without creating an object of the class.

How to Declare Static variable and method in Dart?

• You can declare a static variable or method using the static keyword inside the class.

void main() {
  Car car1 = Car();
  Car car2 = Car();
  
  print('Number of cars created: ${Car.numberOfCars}'); // Output: Number of cars created: 50

  Car.displayCarsInfo();  // Output: Car details are displayed here.
}

class Car {
  // Static variable
  static int numberOfCars = 50;
  
  // Constructor
  Car() {
     print('Car created.');
  }
  
  // Static method
  static void displayCarsInfo() {
    print('Car details are displayed here.');
  }
}

Optional Positional Parameters in Dart Constructor

• In Dart, you can define optional positional parameters (we use them when we want to make some parameters optional) in a constructor by enclosing them in square brackets [].

class Car {
  String color;
  String model;
  
  // Constructor with optional positional parameters
  Car(this.color = 'White', [this.model = 'DefaultModel']);
  
  void displayInfo() {
    print('Car Color: $color, Model: $model');
  }
}
void main() {
  // Creating objects with and without optional parameters
  Car car1 = Car('Red', 'Toyota');
  Car car2 = Car('Blue');
  
  car1.displayInfo(); // Output: Car Color: Red, Model: Toyota
  car2.displayInfo(); // Output: Car Color: White, Model: DefaultModel
}

Named Parameters in Dart Constructor

• In Dart, you can define named parameters (its use to give a name to the parameters) in a constructor by enclosing them in curly braces {}. Named parameters are optional by default, but you can make them required using the required keyword.

class Car {
  String color;
  String model;
  
  // Constructor with named parameters
  Car({required this.color, this.model = 'DefaultModel'});
  
  void displayInfo() {
    print('Car Color: $color, Model: $model');
  }
}
void main() {
  // Creating objects with named parameters
  Car car1 = Car(color: 'Red', model: 'Toyota');
  Car car2 = Car(color: 'Blue');
  
  car1.displayInfo(); // Output: Car Color: Red, Model: Toyota
  car2.displayInfo(); // Output: Car Color: Blue, Model: DefaultModel
}

Named Constructor in Dart

• A named constructor allows you to create multiple constructors for a class with different names.

class Car {
  String color;
  String model;
  
  // Default constructor
  Car(this.color, this.model);
  
  // Named constructor
  Car.redCar() {
    color = 'Red';
    model = 'DefaultModel';
  }
  
  void displayInfo() {
    print('Car Color: $color, Model: $model');
  }
}
void main() {
  // Creating objects using default and named constructors
  Car car1 = Car('Blue', 'Honda');
  Car car2 = Car.redCar();
  
  car1.displayInfo(); // Output: Car Color: Blue, Model: Honda
  car2.displayInfo(); // Output: Car Color: Red, Model: DefaultModel
}

What are Interfaces in Dart?

• Its a list of rules that class must implement.
• Its says "Any class that implements this interface must provide implementations for all the methods defined in the interface."
• Every class automatically defines an interface, which other classes can implement.
• In Interface there are main two things:
  1. Public things
  2. Private things
• Only public things are available to the other classes that implement the interface.
• Private things are not available to the other classes that implement the interface and these are denoted by underscore (_) before the name.

Rescources to Learn Dart

• Courses and Tutorials: Dart And Flutter Series on Youtube ("https://youtube.com/playlist?list=PL9eMLfd38heN2BbPEng6W9qBLl3oJAtwD&si=w_gsoYnIUSzFBLeR")
• Official Dart Documentation: The official Dart website (https://dart.dev) provides comprehensive documentation, tutorials, and guides to help you get started with Dart programming.
• DartPad: An online Dart editor (https://dartpad.dev) that allows you to write, run, and share Dart code directly in your web browser without any setup.
• Flutter Documentation: Since Dart is primarily used with Flutter, the official Flutter documentation (https://flutter.dev/docs) is an excellent resource for learning how to build apps using Dart and Flutter together.