flutterdevrelgists

import 'dart:math';

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;
}

flutterdevrelgists

import 'dart:math';

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;
}

flutterdevrelgists

import 'dart:math';

abstract class Shape {
  num get area;
}

class Circle implements Shape {
  final num radius;
  Circle(this.radius);
  @override

flutterdevrelgists

import 'dart:math';

abstract class Shape {
  factory Shape(String type) {
    if (type == 'circle') return Circle(2);
    if (type == 'square') return Square(2);
    // To trigger exception, don't implement a check for 'triangle'.
    throw 'Can\'t create $type.';
  }
  num get area;

flutterdevrelgists

import 'dart:math';

abstract class Shape {
  num get area;
}

class Circle implements Shape {
  final num radius;
  Circle(this.radius);
  @override

flutterdevrelgists

class Bicycle {
  int cadence;
  int speed;
  int gear;
  
  Bicycle(this.cadence, this.speed, this.gear);
  
  @override
  String toString() => 'Bicycle: $speed mph';
}