void main() {
  print('Hello, World!');
}

List numbers = [1,2,3];

print(numbers.first); // 1
print(numbers.last); // 3

class SomeClass {
  double number;
  callFunction() {}
}
SomeClass nullClass;

final value = nullClass ?? SomeClass();
final number ??= SomeClass().number;

print(nullClass?.callFunction());

class Foo {
    Foo({
    	this.paramOneName = '1',
        this.paramTwoName = '2' });
    
    String paramOneName;
    String paramTwoName;
}

var foo = Foo(paramTwoName: '3');

class Bar {
    Bar();
    
    Foo f1;
    Foo f2;
}

Bar bar = Bar()
    ..f1 = Foo(paramTwoName: '2')
    ..f2 = Foo(paramOneName: '10');

mixin Musical {
  bool canPlayPiano = false;
  bool canCompose = false;
  bool canConduct = false;

  void entertainMe() {
    if (canPlayPiano) {
      print('Playing piano');
    } else if (canConduct) {
      print('Waving hands');
    } else {
      print('Humming to self');
    }
  }
}

class Musician extends Performer with Musical {
  // ···
}

class Maestro extends Person
    with Musical, Aggressive, Demented {
  Maestro(String maestroName) {
    name = maestroName;
    canConduct = true;
  }
}

Future<int> future = Future(asyncFunction);
future.then((int value) {
  print(value);
}).catchError((e) {
  print('Error');
});
 
someFunc () async {
  try {
    int value = await future;
  } catch(e) {
    print('Error');
  }
}

someStream
  .map(...)
  .reduce(...)
  .skip(...)
  .take(...)
  .timeout(...)
  .transform(...)
  .listen((result) {
     print(result);
  })

{
    "name": "Foo",
    "email": "somemail@example.com"
}

import 'package:json_annotation/json_annotation.dart';

part 'user.g.dart';


@JsonSerializable()
class User {
  User(this.name, this.email);

  String name;
  String email;

  factory User.fromJson(Map<String, dynamic> json) => _$UserFromJson(json);
  Map<String, dynamic> toJson() => _$UserToJson(this);
}

abstract class User implements Built<User, UserBuilder> {

  factory User([updates(UserBuilder b)]) = _$User;
  User._();

  @nullable
  String get firstName;

  @nullable
  String get lastName;
}

User user = User((builder) =>
    builder..firstName = 'One'
		   ..lastName = 'Two'
);

User secondUser = user.rebuild((builder) =>
	builder..lastName = 'Three'
);

// user != secondUser

class User
{
  String paramNumberOne      = 1;
  String paramNumbeTwo       = 2;
  String paramNumbeThree     = 3;

  num age;

  num get age => _age;

  set age (num age)
  {
    _age = age;
  }
}

class User {
  String paramNumberOne = 1;
  String paramNumbeTwo = 2;
  String paramNumbeThree = 3;

  num age;
}

dartfmt -w --fix lib 

dartanalyzer --fatal-warnings lib

dartdoc

name: project name
version: 0.0.1

environment:
  sdk: '>=2.4.0 <3.0.0'

dependencies:
  intl: ^0.15.7

import 'package:angular/angular.dart';

@Component(
    selector: 'user-info',
    templateUrl: 'user_info.html')
class UserInfo implements OnInit {
    User(this.dataController)
    
    DataController dataController;

    Stream<String> userName;
	
    void ngOnInit() {
        userName = dataController.info.userName;
    }
}

@JS('draw2d')
library draw2d;

@JS('Canvas')
class Canvas {
  external factory Canvas(String name, [num x, num y]);

  external Canvas add(Figure figure, [num x, num y]);
  external Canvas addSelection(ArrayList /*Figure|List<Figure>*/ object);
  external Canvas clear();
  external void destroy();
  external void fireEvent(String name, [dynamic attr]); /*Object*/
  external Point fromCanvasToDocumentCoordinate(num x, num y);
  external Point fromDocumentToCanvasCoordinate(num x, num y);
  external num getAbsoluteX();
  external num getAbsoluteY();
}