Python - Write program to implement __str__ method

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Requirements

Add __str__ method to MySubSubClass which will extend MySubClass 


class MyClass:               # Define a class object 
    def setdata(self, value):   # Define class's methods 
        self.data = value       # self is the instance 
    def display(self): 
        print(self.data)        # self.data: per instance 

class MySubClass(MyClass):      # Inherits setdata 
    def display(self):          # Changes display 
        print('Current value = "%s"' % self.data)

Hint

__str__ is run when an object is printed.

Demo

class MyClass:               # Define a class object 
    def setdata(self, value):   # Define class's methods 
        self.data = value       # self is the instance 
    def display(self): 
        print(self.data)        # self.data: per instance 
# from w  w w.  j a v  a2  s  . co  m
class MySubClass(MyClass):      # Inherits setdata 
    def display(self):          # Changes display 
        print('Current value = "%s"' % self.data) 
        
class MySubSubClass(MySubClass):# Inherit from MySubClass 
    def __init__(self, value):  # On "MySubSubClass(value)" 
        self.data = value 
    def __add__(self, other):   # On "self + other" 
        return MySubSubClass(self.data + other) 
    def __str__(self):          # On "print(self)", "str()" 
        return '[MySubSubClass: %s]' % self.data 
    def mul(self, other):       # In-place change: named 
        self.data *= other 

a = MySubSubClass('abc')        # __init__ called 
a.display()                     # Inherited method called 
print(a)                        # __str__: returns display string 

b = a + 'xyz'                   # __add__: makes a new instance 
b.display()                     # b has all MySubSubClass methods 
print(b)                        # __str__: returns display string 

a.mul(3)                        # mul: changes instance in place 
print(a)

Result

Related Example