Demonstrate some differences between old-style classes and new-style classes in Python

old_style_vs_new_style_classes.py

class OldStyle():

    def __init__(self):
        print "Init old style"

    def func(self, arg):
        print "Invoked old func with: {}".format(arg)


class NewStyle(object):

    def __init__(self):
        print "Init new style"

    def func(self, arg):
        print "Invoked new func with: {}".format(arg)


class OldSubClass(OldStyle):

    def __init__(self):
        print "Init old sub class"
        OldStyle.__init__(self)

    def func(self, arg):
        print "Invoked old subclass func with: {}".format(arg)
        OldStyle.func(self, arg)


class NewSubClass(NewStyle):

    def __init__(self):
        print "Init new sub class"
        super(NewSubClass, self).__init__()

    def func(self, arg):
        print "Invoked old func with: {}".format(arg)
        super(NewSubClass, self).func(arg)


old = OldSubClass()

print "Old type: {}".format(type(old))
print "Old class: {}".format(old.__class__)

old.func('foo')

new = NewSubClass()

print "New type: {}".format(type(new))
print "New class: {}".format(new.__class__)

new.func('bar')