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Python Object-Oriented Python (retired) Inheritance Intro to Inheritance

Posted by Nitin Chauhan
Nitin Chauhan
Courses Plus Student 277 Points

How does hit_points become an optional argument when it has not been passed as a key to kwargs?

In the video, Kenny passed hit_points as an argument to make the hit_points of the new instance something other than the default value. But we have not specified hit_points as a key of kwargs. Then how does Python know that hit_points is the new key. The reason I am confused has something to do with the following code as well:

class Monster:

def __init__(self, **kwargs):

    self.hit_points = kwargs.get("hit_points", 5)
    self.color = kwargs.get('color', "yellow")
    self.weapon = kwargs.get("arsenal", "kungfu")
    self.sound =  kwargs.get("sound", "roar")

def battlecry(self):
    return self.sound.upper()

In this code, if I create a new instance, and pass weapon as an argument, say

fire_devil = Monster( weapon = "chupwock")

This doesnt't work. It didn't throw any error, and that was surprising too.

However, when I do this,

fire_devil = Monster(arsenal = "chupwock") It works as expected The instance fire_devil is created with weapon as "chupwock". I understand that this happens because "arsenal" is a key of the dictionary kwargs.

But in the code shown in the current video, we have not specified the keys of the dictionary kwargs. Then how does Python know about them? Does it take the attribute name as the key?

Cheo R
Cheo R
37,150 Points
Cheo R
Cheo R
37,150 Points

You can pass a default value to get() for keys that are not in the dictionary. That's why 

fire_devil = Monster( weapon = "chupwock")

doesn't throw an error. The code 

self.weapon = kwargs.get("arsenal", "kungfu")

says, get me "arsenal", if it't not there, then get me the default value "kungfu".

1 Answer

Nitin Chauhan
PLUS
Nitin Chauhan
Courses Plus Student 277 Points
Nitin Chauhan
Nitin Chauhan
Courses Plus Student 277 Points

But how does the code which key to associate to which attribute. I mean what are these default values.

For e.g. when I am saying something like

fire_devil = Monster(experience = 5)

Do you mean that this will associate a value of 5 to self.experience because the attribute is named so?

I hope I am making myself clear. In case I am not, do you mean something like this

instance = Class(some_attribute = num)

and this will associate the value num to some attribute named self.some_attribute?

I am sorry I am not able to understand this.