Inheritance

     So, last time, I wrote an article focusing on the one word computer programs don't know is a word: Polymorphism. Well, before I started talking about it, I mentioned something called inheritance. Let's get to that!
Inheritance: class.__init__(self, classValue)
     Explaining inheritance is a little difficult, as those bold words make no sense, really. Well, we all know what inheritance is. It's what you get from someone else, like red hair from your parents, or maybe the family income, or whatever.
     Well, the programming term is like that. A class inherits attributes/methods from another class. Well, since it's Thanksgiving, I'll give an example related to that holiday. Let's say we were making a game. In this game, you could collect items, like turkeys, coins, pilgrim hats, etc. When the player touches the coin (or turkey/pilgrim hat), there would be a pickUp() method triggered, and it would be added to their bag or whatever is storing everything. We should also have the coins be used to buy things at shops. Well, here is what we might do.

class GameObject: #this is the variable of all the items picked up
    def __init__(self, name):
        self.name = name #name is changed to one of the item classes

    def pickUp(self, player): #here's the function that lets the player pick up the item
        #insert code here to add the object
        #to the player's bag

class Coin(GameObject): #this is known as a subclass, which inherits the attributes (etc.) of a class
    def __init__(self, value):
        GameObject.__init__(self, "coin") #this is what changes name to coin!
        self.value = value

    def spend(self, buyer, seller):
        #insert code here to remove the coin from buyer and give to seller

     Well, this obviously won't work, since we don't have all of the mechanics required to make a game using these objects. You'll just get an error trying to run it.
     Well, this is my example of inheritance. Happy Thanksgiving!

Polymorphism

     We've talked about __init__(), we've talked about __str__(), but something we haven't talked about are two of the most important parts in the object world. Just two big words, and those words are polymorphism and inheritance.
Polymorphism: >= 2
     Polymorphism means you can have at least 2 methods that are the same in different classes that do different things. Confused? Here's an example, and look at the function getArea().
     So, if you wanted to do geometry, here's an example of finding the area.

class Rectangle:
    def __init__(self, width, height):
        self.width = width
        self.height = height

    def getArea(self):
        area = self.width * self.height
        return area

class Cube:
    def __init__(self, size):
        self.size = size

    def getArea(self):
        area = self.size * self.size * self.size
        return area

RectArea = Rectangle(5, 8)
CubeArea = Cube(4)

     Now run the program, and type this in:

>>> RectArea.getArea()
40
>>> CubeArea.getArea()
64
>>>

     Ta-da! Both classes used getArea(), but did different things and had different outcomes. That is polymorphism.
     Next time, we will study inheritance. Brace yourself, these articles will never be simple again!

A Quick Tip - Alphabetical Order

     As I was looking through one of my old list articles, I realized that there's a function I don't remember writing about. This function is known as sort().

     Sort() is a function that sorts all items in a list in alphabetical order. Isn't that neat? Let's show an example of this. If you need to sort a bunch of words in alphabetical order, you can do it in a snap! Let's make a list:

words=['Exuberant', 'Philosophy', 'Pterodactyl', 'Potato', 'Avenue', 'Boulevard', 'Rendezvous', 'Embryonic']

     (Yes, those are real words)
     So, we use sort() like this:

words.sort()

     Now, let's print(words):

['Avenue', 'Boulevard', 'Embryonic', 'Exuberant', 'Philosophy', 'Potato', 'Pterodactyl', 'Rendezvous']

     Takes the pressure of of things, eh? Now I know you know the sort() function. Sorry it took so long to figure out that I didn't tell you this earlier!

Timer

     Remember that short article that talked about sleeping time? I figured we should practice it! The only things we've been doing with time is giving the user some time to read a message before the next one comes up. There is way more to it than that, though! Here's another program I wrote a very long time ago. It's a timer (that figures, since the title of this article is "Timer").
     Let's see the program:

import time, easygui

choices=easygui.buttonbox("Do you want the time to go in seconds, minutes, or hours?", choices=['Seconds', 'Minutes', 'Hours'])
if choices == 'Seconds':
    time2=easygui.integerbox("Seconds. OK. How many seconds?")
    for i in range(time2, 0, -1):
        print(time2)
        print(time2 * "*")
        time.sleep(1)
        time2=time2-1
elif choices == 'Minutes':
    time3=easygui.integerbox("How many minutes?")
    for j in range(time3, 0, -1):
        print(time3)
        print(time3 * "*")
        time.sleep(1*60)
        time3=time3-1
else:
    time4=easygui.integerbox("Long times. How many hours?")
    for k in range(time4, 0, -1):
        print(time4)
        print(time4 * "*")
        time.sleep(1*60*60)
        time4=time4-1

easygui.msgbox("Time's up!")

     It may seem a little complicated, but let's just see what happens when it runs.

10
**********
9
*********
8
********
7
*******
6
******
5
*****
4
****
3
***
2
**
1
*

     Not too complicated, really. The asterisks were mainly for fun, so let's just move on to the real numbers.

for i in range(time2, 0, -1):

     We already know about this part, we talked about it in the For Loops article.

        print(time2)
        print(time2 * "*")
        time.sleep(1)
        time2=time2-1

     Well, we print time2. And then we print as many asterisks as time2 is. Then we wait a second, and then we recreate the variable.
     So, this is another part of the world of time. Now you can use this program to your heart's content! I challenge you to find out if time2=time2-1, time3=time3-1, and time4=time4-1 are pointless!

Debugging Part 3 - Pumpkin Carving

     So, as you remember in the last article, our program had an error. When you get accustomed to them, you can figure out what they are saying. It's the last line that gives you the reason the program crashed.

Traceback (most recent call last):
  File "C:/Python33/Pumpkins.py", line 79, in <module>
    easygui.msgbox("A pumpkin with", Pumpkin.eyes, "eyes, a", Pumpkin.nose, "nose, and a", Pumpkin.mouth, " ", Pumpkin.expression, ".")
TypeError: msgbox() takes from 0 to 5 positional arguments but 9 were given

     Let's take a look at the last line.

TypeError: msgbox() takes from 0 to 5 positional arguments but 9 were given

     So, EasyGUI messagebox had too many variables to work with, or something. I'm not sure, so let's just figure it out. Let's start by changing the msgbox into a print statement.

print("The pumpkin has", Pumpkin.eyes, "eyes, a", Pumpkin.nose, "nose, and a", Pumpkin.mouth, " ", Pumpkin.expression, ".")

     Did that work?

Time to carve some pumpkins!
First things first...
The pumpkin has Fire eyes.
Okay, let's do the nose.
The pumpin has a Arrowhead nose.
Now, the mouth! But first...
The pumpkin has a Smile .
Now...
The pumpkin has a Round mouth.
Here's your entire combination:
The pumpkin has Fire eyes, a Arrowhead nose, and a Round   Smile .

     Really, that was it? Wow. It pays off to actually read the errors, doesn't it? There must be some way around that arguments thing on EasyGUI, but that's probably gonna be extremely hard to find. Well, I guess Halloween is over, but if I do search for that way around, Halloween will spring back up!
     I challenge you to find a way around the error while still using EasyGUI (if that's even possible)!