Question

I am trying to make a class with generic __init__ values, but have defaults for its subclasses, as so:

class Enemy:

 def __init__(self, difficulty, power, MaxHP, magic, MaxMP, speed, name):
    self.power = power + 2*difficulty
    self.HP = self.MaxHP = MaxHP + 5*difficulty
    self.magic = magic + 2* difficulty
    self.MP = self.MaxMP = MaxMP + 5*difficulty
class Goblin(Enemy):
 def __init_(self, difficulty = 1, power = 1, MaxHP = 5, magic = 1, MaxMP = 5, speed = 5, name = "Goblin"):
    super(Goblin, self).__init__(self, power, MaxHP, magic, MaxMP, speed, name)

However, when I try to make a Goblin object without the full number of default values (like, I’ll just put in a value for difficulty), it tells me I need the full 8 arguments even though the rest are given default values. Is there any reason I can’t do that or am I doing something wrong here?

Answer 1

Because you called super(Goblin, self).__init__(self, power, MaxHP, magic, MaxMP, speed, name) without difficulty. You probably also want to inherit like class Enemy(object) to make sure Enemy is a new-style class if you’re on 2.x (which I guess you must be, considering the old way that you’ve used super).

Here’s a simpler example:

class Animal(object):
  def __init__(self, talk):
    print '__init__ Animal: ', talk

class Cat(Animal):
  def __init__(self, talk='meow'):
    print '__init__ Cat'
    super(Cat, self).__init__(talk)

if __name__ == '__main__':
  tom = Cat()

Outputs :

__init__ Cat
__init__ Animal:  meow

---

Edit:

Well if the following doesn’t work, perhaps you have old class definitions cached in your interpreter (try running it on a fresh interpreter).

class Enemy(object):
  def __init__(self, difficulty, power, MaxHP, magic, MaxMP, speed, name):
    self.power = power + 2*difficulty
    self.HP = self.MaxHP = MaxHP + 5*difficulty
    self.magic = magic + 2* difficulty
    self.MP = self.MaxMP = MaxMP + 5*difficulty
    print 'Raaarghh!! I am the formidable {}.'.format(name)

class Goblin(Enemy):
  def __init__(self, difficulty=1, power=1, MaxHP=5, magic=1, MaxMP=5, speed=5, name="Goblin"):
    super(Goblin, self).__init__(difficulty, power, MaxHP, magic, MaxMP, speed, name)

if __name__ == '__main__':
  g = Goblin(name='user1038783 goblin')