Understanding inheritance with python classes

Question

so I am trying to understand how to build child classes in python.

So ive created a perent and a child class but I just cant understand how to get them to work

so this is my current code

from abc import ABCMeta, abstractmethod

class Persion(object):
    __metaclass__ = ABCMeta # sets the metaclass to a abstract base class . that means we never call this class directley insted its used for child classes to inhearrit
    def __init__(self, name, gender):
        self.name = name
        self.gender = gender

    def talk(self):
        print("hi my name is " + self.name + " and I am a " + self.gender + ".")

    @abstractmethod
    def PersionType(self):
        """Returns a string of the childs type"""
        pass

class Player(Persion):
    def __int__(self,speed):
        self.name = name
        self.gender = gender
        self.speed = speed
        self.posX = 0
        self.posY = 0

    def moveXY(self, X, Y):
        self.posX = X
        self.posY = Y

    def PersionType(self):
        return 'Player'

player=Persion("Ben","m")
hero = Player(player,30)
hero.moveXY(20,20)
print("you are now at ", hero.posX, "," , hero.posY)
print("your speed is ", hero.speed)
print("your gender is ", hero.gender)
hero.talk()

so the end result is I want these functions to work. but something has gone rong in buildign the inhertance thats what I want to find out.

hero.moveXY(20,20)
print("you are now at ", hero.posX, "," , hero.posY)
print("your speed is ", hero.speed)
print("your gender is ", hero.gender)
hero.talk()

im getting errors sutch as

 line 36, in <module>
    print("your speed is ", hero.speed)
AttributeError: 'Player' object has no attribute 'speed'

I am making this to help me understand how inheratince works in python.

Karin · Accepted Answer · 2016-08-17 01:30:23Z

2

There are three main problems with your code:

Change __int__ to __init__. Your instance isn't getting initialized, which is why you get the no attribute 'speed' error.
Your subclass (the class that's inheriting, which in this case is Player) should have an __init__ method that takes all the arguments you want associated with it. You can pass the ones used by the superclass (Persion) to the superclass's __init__. That means probably changing the __init__ method to:
```
class Player(Persion):
    def __init__(self, name, gender, speed):
        super(Player, self).__init__(name, gender)
        self.speed = speed
        self.posX = 0
        self.posY = 0
```
Now, when creating the instances, you need only create an instance of the subclass. It will inherit the methods from the superclass:
```
hero = Player('Ben', 'm', 30)
```

With these changes, these lines:

print("you are now at ", hero.posX, "," , hero.posY)
print("your speed is ", hero.speed)
print("your gender is ", hero.gender)
hero.talk()

Now produce this output:

you are now at  20 , 20
your speed is  30
your gender is  m
hi my name is Ben and I am a m.

Additional small notes:

You probably want the class to be named Person instead of Persion.
The @abstractmethod method should not be needed.

edited Aug 17, 2016 at 1:30

answered Aug 17, 2016 at 1:24

Karin

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1 Comment

skyzzle Over a year ago

Thank you you explained that so well. I did not realize it was something as simple as a spelling mistake. So it makes seance but I still don't fully understand that the line super(Player, self).__init__(name, gender) I get the rough idea on what it is doing. setting the values from the supper/parent class but I don't understand clearly what this super() function is doing.

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