__str__ is tried first for user-friendly displays : str « Class « Python Tutorial

1. Python Tutorial
2. Class
3. str

class adder: 
    def __init__(self, value=0): 
        self.data = value                      
    def __add__(self, other): 
        self.data += other                     



class addstr(adder): 
    def __str__(self):                         
        return '[Value: %s]' % self.data       

x = addstr(3) 
x + 1 
x                                              

print x                                        

str(x), repr(x)