Class definition

#!/usr/bin/env python

class MyClass( object):
    """
    A simple example class
    """
    # 
    # i is a class variable
    # 
    i = 1
    #
    # the constructor
    #
    def __init__( self):
        print( " __init__")
        self.data = []
        #        
        # this is how to deal with errors in the constructor
        #        
        if someThingIsWrong:
             raise Exception( "MyClass", "something is wrong")
    #
    # __del__() is called by the garbage collector, not 
    # when the last reference to an object is lost, e.g.
    # by executing 'del obj'. 
    # !!! do not use __del__() !!!
    #
    def __del__( self):
        print( " __del__")

    def f( self):
        MyClass.i += 1
        return 'hello world'

x = MyClass();
                 # -> __init__
print( "%s" %  x.f())
                 # -> hello world
print( " i %d" % MyClass.i)
                 # -> i 2
                 # -> __del__

Data members need not to be declared. We can start with an empty class:

#!/usr/bin/env python

class Employee(object):
    pass

john = Employee() # Create an empty employee record

# Fill the fields of the record
john.name = 'John Doe'
john.dept = 'computer lab'
john.salary = 1000

print( john.name)