Dart Primer tutorial by Net Ninja on the basics of dart

main.dart

void main() {

  //Instantiating a class
  User userOne=User('caleb', 24);
  
  //calling an attribute/property of the class
  print(userOne.username);
  print(userOne.age);
  
  User userTwo = User('mercy',23);
  
  print(userTwo.username);
  print(userTwo.age);
  
  //Invoking a function from the class
  userOne.login();
  
  
  
  /*Inheritance*/
  
  SuperUser userThree = SuperUser("Humphrey",58);
  
  print(userThree.username);
 
  /*Invoking the extra method from the inherited class*/
  
  userThree.publish();
  
  /*has access to methods from the parent class*/
  
  userThree.login();
  
}


class User {
  
  //class attributes
  String username;
  int age ;
  
  //constructor function
  //Should have the same name as the class
  //It is a special type of function therefore 
  //does not take void
  User(String username , int age ){
    this.username =username;
    this.age=age;
    
  }
  void login (){
    
    print('user logged in');
  }
  
}

/*Inheritance*/

/*The SuperUser class wants to inherit from the User
 but have some added functionlities which a normal
 user should not have
 */
class SuperUser extends User{
 
  //super calls the constructor from the class it extends from
  //and passes those values in.
  /* We as well inherit the functions of the previous
  class plus it now has an added function/method.
  */
  
  SuperUser(String username, int age ):super(username,age);
  
  void publish (){
    print("published update!");
  }
}