Creating instances in python

Question

I'm having trouble understanding what a class instance is. I read up on the syntax page for classes in python. However, i'm still having difficulty fully grasping the meaning of an instance. For example, lets say I create a class that has two slots containing an "item" and a "key". In my case, I know how to initialize the objects using def __init__(self): with self.key = key and self.name = name. However, my problem deals with creating an instance that takes in two parameters. Similarly, how would I make an instance a stack? I don't really want any code, however can someone describe the solution in simple terms? Thanks guys!

@drewk -

class morning(object):
     __slots__ = ('key', 'name')

     def __init__(self, name, key):
         self.name = name
         self.key = key
         return self

Answer 1

It is the difference between an instance variable and class variable:

class Test(object):
    x='CLASS x my man'
    def __init__(self, x=0, y=1):
        self.x=x
        self.y=y

t1=Test(3,4)   
t2=Test(5,6)
print 't1:', t1.x    
print 't2:', t2.x
print 'class:', Test.x

Prints:

t1: 3
t2: 5
class: CLASS x my man

Answer 2

Extracts from my newb tutorial.

class Fruit:
    """ An Eatables Class"""
    def __init__(self, color="Black", shape="Round"): # Initailization
        self.color = color    # Set Class Variables to passed values
        self.shape = shape    # If no value passed, default to hard-coded ones.

Mango = Fruit("Raw Green", "Mangool")
# Above statement instantiates Class Fruit by passing variables as arguments.
# Thus, Mango is an **instance** of class **Fruit**

Now, accessing the variables

>>>print Mango.color
Raw Green

Another Example

class My_List:
    """My List Implementation"""
    def __init__(self, *args):
        self.data = list(args)
        self.Length = len(args)

    def GetMean(self):
        return 1.0*sum(self.data)/len(self.data)

    def Add(self, *args):
        self.data.extend(list(args))
        self.Length += len(args)

whole_num = My_List(0,1,2,3,4,5)
# Made an **instance** of class **My_List**

Variable accession

>>>print whole_num.GetMean()
2.5
>>>whole_num.Add(6, 7)
>>>print whole_num.data
[0, 1, 2, 3, 4, 5, 6, 7]