objvar.py

class Person:
    population=0

    def __init__(self,name):
        self.name=name
        print'(Initializing %s)' %self.name
        Person.population += 1
    
    def __del__(self):
        print'%s says bye.' %self.name
        Person.population -= 1

        if Person.population == 0:
            print'I am the last one.'
        else:
            print'There are still %d people left.' %Person.population

    def sayHi(self):
        print'Hi, my name is %s.' %self.name

    def howMany(self):
        if Person.population == 1:
            print'I am the only person here.'
        else:
            print'We have %d persons here.' %Person.population

eric = Person('Eric')
eric.sayHi()
eric.howMany()

leo = Person('Leo')
leo.sayHi()
leo.howMany()