introduction to dart

intro_to.dart

// import 'dart:async';
// import 'dart:math';

// every dart program starts with main function

void main() {
//   basic data types
//   1. bool
//   2. int
//   3. double
//   3. String
//   4. dynamic
//   5. var
//   6. late
  
//   if you don't specify type, dart uses type inference
//   var hours = 24;
//   print(hours);
  
//   this will bypass type inference
//   dynamic name = 'dart';
//   print(name);
  
//   functions
//   String greet(String name) {
//     String decorate() => '## $name ##'; // nested function
//     return 'Hello, ${decorate()}';
//   }
  
//   print(greet('Function'));
  
//   dynamic orphan = () {
//     return 'anonymous function';
//   };
  
//   print(orphan());
  
//   keyword late
  
//   int getSum() {
//     print('expensive function');
//     return 0;
//   }
  
//   late int sum = getSum();
//   sum;
  
//   Objects act as data type
//   1. Map
//   2. List
//   3. Set
//   4. Queue
//   5. enum
  
//   Map<String, int> map = {'age': 27, 'height': 175};
//   print(map);
  
//   List<int> numbers = [1,2, 3, 3, 5, 7, 8, 8, 9];
//   print(numbers.asMap().keys.toList());
  
//   Set set = Set.from(numbers); 
//   Set.from is a named constructor we will see later in classes and objects
//   print(set);

//   enum State { inProgress, success, failed }
  
  classes();
}

// classes --------------------------------------

// class Car {
  
//   final String price;
//   final String engine;
//   String color;
  
//   Car(this.price, this.engine, this.color);
  
//   static Tata tata() {
//     return Tata();
//   }
  
//   factory Car.buildTata() { // similar to static function, but must return same class type
//     return Tata(); 
//   }
  
//   String details() {
//     return "Name\tPrice\tEngine\tColor\n--\t--\t--\n$runtimeType\t$price\t$engine\t$color";
//   }
// }

// class Tata extends Car {
//   Tata() : super('15L', '1.5L', 'White');
// }

// abstract classes -------------------------
// abstract class Car {
//   // abstract classes can't be instantiated
//   // useful to avoid boilerplate code, etc.
//   final String price;
//   final String engine;
//   final String color;
  
//   Car(this.price, this.engine, this.color);
  
//   String get details => "Name\tPrice\tEngine\tColor\n--\t--\t--\n$runtimeType\t$price\t$engine\t$color";
// }

// class Tata extends Car {
//   Tata() : super('10L', '1.5L', 'Silver');
// }


// interface classes ---------------------------
// class Car {
  
//   final String price;
//   final String engine;
//   String color;
  
//   Car(this.price, this.engine, this.color);
  
//   static Tata tata() {
//     return Tata();
//   }
// }

// class Details {
//   // interface is like a blueprint for it's subclasses
//   String details() {
//     throw UnimplementedError('function `details` is not defined for $runtimeType');
//   }
// }

// class Tata extends Car implements Details {
//   Tata() : super('10L', '1.5L', 'Silver');
  
//   @override
//   String details() {
//     return "Name\tPrice\tEngine\tColor\n--\t--\t--\n$runtimeType\t$price\t$engine\t$color";
//   }
// }


// mixin classes -----------------------------
// dart doesn't support multiple inheritance to avoid Deadly Diamond of Death (DDD)
// https://en.wikipedia.org/wiki/Multiple_inheritance#:~:text=The%20%22diamond%20problem%22%20(sometimes,from%20both%20B%20and%20C.

// that's where mixin come into play 😊
// and dart supports multiple mixin

// class Point {
//   // (x,y) coordinates
//   late int x; // late tells compiler don't worry you will get it when you need it
//   late int y;
     
//   double distanceFrom(Point other) {
//     int dx = other.x - x;
//     int dy = other.y - y;
//     return sqrt(dx * dx + dy * dy);
//   }
// }

// class Point2 {
//   // (x,y) coordinates
//   late int x; // late tells compiler don't worry you will get it when you need it
//   late int y;
     
//   double distanceFrom(Point other) {
//     print('😛');
//     return 0;
//   }
// }

// class Perimeter {
//   late int height;
//   late int width;
    
//   int get area => 2 * height * width;
// }

// // if two mixin's have same methods the latter wins
// class Rectangle extends Perimeter with Point, Point2 {}


// generic types ------------------
// class StateController<State> { // State is one of type {int, List, CustomType} 
//   State _state;
  
//   StateController(this._state);
  
//   State get state => _state;
  
//   void modify(State newState) {
//     _state = newState;
//   }
// }

// class Todo {
//   final int id;
//   final String desc;
  
//   Todo(this.id, this.desc);
  
//   @override
//   String toString() {
//     return "\nid\tdesc\n$id\t$desc\n";
//   }
// }

void classes() {
//   class example ---------------
//   Car tata = Car('10L', '1.5L', 'RoyalBlue');
//   print(tata.details());
  
//   Car sTata = Car.tata();
//   print('\nusing static function\n${sTata.details()}');
  
//   Car fTata = Car.buildTata();
//   print('\nusing factory function\n${fTata.details()}');
  
//   abstract classes example ---------------
//   Car tata = Tata();
//   print(tata.details);
  
//   interface example ---------------
//   Tata tata = Tata();
//   print(tata.details());
  
//   mixin example --------------
//   Point origin = Point()
//     ..x = 0
//     ..y = 0; // cascade notation
  
//   Rectangle rect = Rectangle()
//     ..x=10
//     ..y=10
//     ..height=40
//     ..width=40;
  
//   print(rect.distanceFrom(origin)); // call to mixin method
//   print(rect.area);
  
// generic types
//   print('intController ------------');
//   StateController<int> intController = StateController<int>(0);
//   print(intController.state);
//   intController.modify(5);
//   print(intController.state);
  
//   print('\nstringController ------------');
//   StateController<List<String>> stringController = StateController<List<String>>([]);
//   print(stringController.state);
//   stringController.modify(['Welcome to dart types']);
//   print(stringController.state);
  
//   print('\ntodoController ------------');
//   StateController<Todo> todoController = StateController<Todo>(Todo(0, ''));
//   print(todoController.state);
//   todoController.modify(Todo(1, 'done with dart'));
//   print(todoController.state);
  
//   StateController<List<Todo>> todosController = StateController<List<Todo>>([]);
//   print("\n${todosController.state}");
//   todosController.modify([
//     Todo(1, 'entry 1'),
//     Todo(2, 'entry 2'),
//     Todo(3, 'entry 3'),
//   ]);
//   print("\n${todosController.state}");
}