FlutterSurf_2_10_1

void main(List<String> arguments) {
  print('Hello world!');

  var student = Student('mikhail', 'ushanov', DateTime(2018, 01, 01));
  print(student);
}

// 2.10 1
class Student extends User {
  DateTime yearOfAdmission;
  int currentCourse;

  Student(lastName, firstName, this.yearOfAdmission)
      : super(lastName, firstName) {

    currentCourse = DateTime.now().year - yearOfAdmission.year;
  }

  @override
  String toString() {
    return 'name: ${super.toString()},  yearOfAdmission: ${yearOfAdmission.year}, currentCourse: ${currentCourse}';
  }
}

class User {
  String lastName;
  String firstName;

  User(this.lastName, this.firstName);

  @override
  String toString() {
    return '$lastName $firstName';
  }
}

FlutterSurf_2_10_2

void main(List<String> arguments) {

  print(Color.red);

  var truck = Truck(Color.green);
  print(truck.toString());
  truck.run();

  var sportcar = Sportcar(Color.yellow);
  print(sportcar.toString());
  sportcar.run();

  var bike = Bike(Color.red);
  print(bike.toString());
}

abstract class Car {
  double weight;
  void run();
}

class Truck extends Car with Painter, Engine{

  Truck(Color color) {
    setColor(color);
  }

  @override
  double get weight => 10;

  @override
  void run() {
    runEngine();
  }

  @override
  String toString(){
    return 'Грузовик $colorName цвета';
  }
}

class Sportcar extends Car with Painter, Engine{

  Sportcar(Color color) {
    setColor(color);
  }

  @override
  double get weight => 2;

  @override
  void run() {
    runEngine();
  }

  @override
  String toString(){
    return 'Спорткар $colorName цвета';
  }
}

class Bike with Painter{

  Bike(Color color) {
    setColor(color);
  }

  @override
  String toString(){
    return 'Велосипед $colorName цвета';
  }
}

enum Color {red, yellow, green}
const Map<Color, String> ColorName = {
  Color.red: 'red',
  Color.yellow: 'yellow',
  Color.green: 'green',
};

mixin Painter {
  String _colorName;
  void setColor(Color color) { _colorName = ColorName[color]; }
  String get colorName => _colorName;
}

mixin Engine on Car {
  int get enginePower => 100;

  void runEngine() {
    print('Двигатель работает. Максимальная скорость = ${enginePower / weight}');
  }
}

FlutterSurf_2_10_3

void main(List<String> arguments) {
  var printer = Printer();

  print(printer.print('string'));
  print(printer.print(101));
  print(printer.print(DateTime.now()));
}

class Printer {
  String print<T>(T data){
    return data.toString();
  }
}