1. Python Classes
Python has Classes, Methods, Overloaded operators, as well as Inheritance. Its somewhat 'loose' in the since it does not have true encapsulation, but its interesting anyway. You can write nice OOP applications as long as you don't cheat.

2. Basic Class Syntax class Name: [body] Example with constructor
class Rectangle:
def __init__(self,x,y): # parameterize constructor
self.width=x #declare instance variable width
self.height=y #declare instance variable height
rect=Rectangle(2,5) # allocates rectangle instance
print rect.width,rect.height #hmmmm

3. Class Variables class Rectangle:
count=0 #class variables declared here
def __init__(self,x,y):
Rectangle.count+=1
self.width=x
self.height=y
r= Rectangle(3,4)
s= Rectangle(9,4)
t= Rectangle(3,6)
print Rectangle.count
Outputs 3

4. Define output format of instance
class Complex:
def __init__(self,r,i):
self.real=r
self.imag=i
def __str__(self):#this is how it prints
if self.imag<0:
return str(self.real)+str(self.imag)+"i"
else:
return str(self.real)+'+'+str(self.imag)+"i"
x=Complex(-1,-2)
y=Complex(2,5)
print x,y # uses __str__ to display the instances
Output is -1-2i 2+5i

5. Add method for Complex class Complex: def __init__(self,r,i):
self.real=r
self.imag=i
def Add(self,c):
return Complex(self.real+c.real,self.imag+c.imag)
def __str__(self):#this is how it prints
if self.imag<0:
return str(self.real)+str(self.imag)+"i"
else:
return str(self.real)+'+'+str(self.imag)+"i"
x=Complex(-1,-2)
y=Complex(2,5)
z=x.Add(y)
print z Output is 1+3i

6. Destructors ??
Destructors are a big deal in C++ but not as much so in Python.
Why? Well Python has automatic garbage collection using reference counting.
This does not mean there is no need for destructors.
You may want to clean up other allocated things like sockets and database connections to be closed, files, buffers and caches flushed and a few more resources that need to be released when an object is done with them.

7. Destructor Example class FooType(object): def __init__(self, id):
self.id = id
print self.id, 'born'
def __del__(self):
print self.id, 'died'
def make_foo():
print 'Making...'
ft = FooType(1)
print 'Returning...'
return ft
print 'Calling...'
ft = make_foo()
print 'End...'
Note: Python won't clean up an object when it goes out of scope. It will clean it up when the last reference to it has gone out of scope. Here is its output
Calling...
Making...
1 born
Returning...
End...
1 died
Note2: Don’t use destructors unless you really need to.

8. Longer Example import datetime class Person: def __init__(self,name):
self.name = name
try:
lastBlank = name.rindex(' ')
self.lastName = name[lastBlank+1:]
except:
self.lastName = name
self.birthday = None
def getName(self):
return self.name
def setBirthday(self,birthdate):
self.birthday = birthdate
def getAge(self):
if self.birthday == None:
raise ValueError
return (datetime.date.today()-self.birthday).days
def __str__(self):
return self.name
me =Person('Thomas Adams') me.setBirthday(datetime.date(1956,1,31))
print me,'is',me.getAge(),'days old'
Thomas Adams is days old