Dart / Flutter myNotes

abstract_factory.dart

import 'dart:math';

/* 
abstract class Shape {
  num get area;
}
*/

abstract class Shape {
  factory Shape(String type) {
    if (type == 'circle') return Circle(2);
    if (type == 'square') return Square(2);
    throw 'Can\'t create $type.';
  }
  num get area;
}

class CircleMock implements Circle {
  num area;
  num radius;
}

class Circle implements Shape {
  final num radius;
  Circle(this.radius);
  num get area => pi * pow(radius, 2);
}

class Square implements Shape {
  final num side;
  Square(this.side);
  num get area => pow(side, 2);
}

Shape shapeFactory(String type) {
  if (type == 'circle') return Circle(2);
  if (type == 'square') return Square(2);
  throw 'Can\'t create $type.';
}

main() {
  // final circle = Circle(3.45);
  // final square = Square(5);

  /*
  final circle = shapeFactory('circle');
  final square = shapeFactory('square');
  */

  final circle = Shape('circle');
  final square = Shape('square');
  print(circle.area);
  print(square.area);
}

class.dart

import 'dart:math';

class Rectangle {
  int width;
  int height;
  Point origin;
  
  Rectangle({this.origin = const Point(0, 0), this.width = 0, this.height = 0});
  
  @override
  String toString() =>
    'Origin: (${origin.x}, ${origin.y}), width: $width, height: $height';
}

main() {
  print(Rectangle(origin: const Point(10, 20), width: 100, height: 200));
  print(Rectangle(origin: const Point(10, 10)));
  print(Rectangle(width: 200));
  print(Rectangle());
}

class_implement_interface.dart

import 'dart:math';
​
abstract class Shape {
  num get area;
}
​
class Circle implements Shape {
  final num radius;
  Circle(this.radius);
  num get area => pi * pow(radius, 2);
}
​
class Square implements Shape {
  final num side;
  Square(this.side);
  num get area => pow(side, 2);
}
​
main() {
  final circle = Circle(3.45);
  final square = Square(5);
  print(circle.area);
  print(square.area);
}

Java2Dart_imperative_code.dart

String scream(int length) => "A${'a' * length}h!";

main() {
  final values = [1, 2, 3, 5, 10, 50];
  for (var length in values) {
    print(scream(length));
  }
  
  // OR 
  values.map(scream).forEach(print);
  
  // OR
  values.skip(1).take(3).map(scream).forEach(print);
}

https://dartpad.dartlang.org/ to test