class adder:
def __init__(self, value=0):
self.data = value # initialize data
def __add__(self, other):
self.data += other # add other in-place
class addrepr(adder): # inherit __init__, __add__
def __repr__(self): # add string representation
return 'addrepr(%s)' % self.data # convert to string as code
class addstr(adder):
def __str__(self): # __str__ but no __repr__
return '[Value: %s]' % self.data # convert to nice string
x = addstr(3)
x + 1
print x # runs __str__
print str(x), repr(x)