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Python Object-Oriented Python Inheritance Super-Duper!

Paul Melos
Paul Melos
3,905 Points
Posted by Paul Melos
Paul Melos
3,905 Points

What does Kenneth mean that you can't set sneaky?

He says in the video that we've lost the ability to set sneaky...

Since Character class accepts kwargs, wouldn't you just pass it when you initialize a thief object??

like this:

obj = Thief("bill", sneaky=True)

import random

class Character:
    def __init__(self, name, **kwargs):
        self.name = name

        for key, value in kwargs.items():
            setattr(self, key, value)


class Thief(Character):
    sneaky = True

    def pickpocket(self):
        return self.sneaky and bool(random.randint(0, 1))

    def hide(self, light_level):
        return self.sneaky and light_level < 10

2 Answers

CHRISTOPHER CONNOR
CHRISTOPHER CONNOR
4,740 Points

We want the Thief to have sneaky as an ability as standard rather than using it as an add on using **kwargs.

In the same way if we decided to create a class for a Knight character you could have sword as standard when creating the Knight and not need to add sword using kwargs.

obj = Knight("Arthur", "Excalibur")

rather than

obj = Knight("Arthur", sword="Excalibur")

I hope that makes sense like it does in my head :)

Paul Melos
Paul Melos
3,905 Points
Paul Melos
Paul Melos
3,905 Points

Thank you Christopher, it sure does. Between your explanation and fussing around with the workspace, it is making more sense. To anybody else who needs an illustrative example, pay close attention to the ability pass "True" for sneaky before and after super() is used to override the parent classes's init method. You may have to go back to the "Methods" video where Kenneth introduces us to the init method.

Before adding the Character parent class you can initialize a thief object and set sneaky like so: 

obj = Thief("Bill". True)

After adding the Character parent and removing the init method from the Thief subclass, you will get an error. I had to remind myself that this is a complicated topic and Kenneth had to figure out a simple way to introduce super(), which in itself made super() confusing because the example was so simple.

So then why use super() in real life? Still figuring that out, but I believe this has implications for DRY as your classes and subclasses become more intricate. You don't want to have to remember to pass kwargs every time you initialize a class. Also something that every answer in the googlenets mentions is Method Resolution Order, MRO which is another complex topic, but super() seems to be used to control the way your subclasses recieve or don't receive methods from thee parent classes via manipulating the MRO.

More here https://rhettinger.wordpress.com/2011/05/26/super-considered-super/

Mark Chesney
Mark Chesney
11,747 Points
Mark Chesney
Mark Chesney
11,747 Points

Hi Paul. Yes, I'm still figuring super() and OOP out myself, but you're correct -- by using super() when we initialize a Thief() or a Knight(), we reduce written code. After all, all characters have the ordinary character attributes, including name. But not all characters have a sneaky attribute, or a sword/Excalibur attribute. I think Christopher's example is a good one.

Ewerton Luna
.a{fill-rule:evenodd;}techdegree seal-36
Ewerton Luna
Full Stack JavaScript Techdegree Graduate 24,031 Points

Can you tell me if I understood this right? What if I wrote my code like this (just for the sake of it)

class Thief(Character):
    sneaky = True

    def __init__(self, name, sneaky = True, **kwargs):
        self.name = name
        self.sneaky = sneaky

        for key, value in kwargs.items():
            setattr(self, key, value)

Let's pretend I never heard about the super() function, so I wrote my code like this. Can I say that this code does the same thing and works just as Kenneth's? If so, I come to the conclusion that super() helps you to write less code, because I don't have to repeat what I wrote in the super class (among other things I've not learned yet).