What does inheritance mean in OOP?
Inheritance is the core feature of object-oriented programming which extends the functionality of an existing class by adding new features. You may compare it with real-life situations when a child inherits the property of his parents in addition to adding his own. He may even derive the surname (the second name) from his parents.
What is the purpose of inheritance?
By using the inheritance feature, we can have a new blueprint with old attributes but without making any changes to the original one. We refer to the new class as the derived or child class whereas the old one becomes the base or parent class.
Python Inheritance & OOP Concepts
How to implement inheritance in Python?
You can introduce inheritance by using the following syntax.
class ParentClass:
Parent class attributes
Parent class methods
class ChildClass(ParentClass):
Child class attributes
Child class methodsInheritance automatically brings reusability to your code as the derived class has got everything from the base class.
Give an example of Python Inheritance
To understand the application of inheritance, let’s consider the following example.
Create a base class Taxi and a subclass Vehicle
We have a base class Taxi, and it has a subclass (child) Vehicle.
class Taxi:
def __init__(self, model, capacity, variant):
self.__model = model # __model is private to Taxi class
self.__capacity = capacity
self.__variant = variant
def getModel(self): # getmodel() is accessible outside the class
return self.__model
def getCapacity(self): # getCapacity() function is accessible to class Vehicle
return self.__capacity
def setCapacity(self, capacity): # setCapacity() is accessible outside the class
self.__capacity = capacity
def getVariant(self): # getVariant() function is accessible to class Vehicle
return self.__variant
def setVariant(self, variant): # setVariant() is accessible outside the class
self.__variant = variant
class Vehicle(Taxi):
def __init__(self, model, capacity, variant, color):
# call parent constructor to set model and color
super().__init__(model, capacity, variant)
self.__color = color
def vehicleInfo(self):
return self.getModel() + " " + self.getVariant() + " in " + self.__color + " with " + self.getCapacity() + " seats"
# In method getInfo we can call getmodel(), getCapacity() as they are
# accessible in the child class through inheritance
v1 = Vehicle("i20 Active", "4", "SX", "Bronze")
print(v1.vehicleInfo())
print(v1.getModel()) # Vehicle has no method getModel() but it is accessible via Vehicle class
v2 = Vehicle("Fortuner", "7", "MT2755", "White")
print(v2.vehicleInfo())
print(v2.getModel()) # Vehicle has no method getModel() but it is accessible via Vehicle class
Please note that we have not specified the getName() method in the Vehicle class, but we can access it. It is because the Vehicle class inherits it from the Taxi class.
The output of the above example is as follows.
# output
i20 Active SX in Bronze with 4 seats
i20 Active
Fortuner MT2755 in White with 7 seats
FortunerPython inheritance’s UML diagram
To bring more clarity, you can refer the below Python inheritance’s UML diagram of the example mentioned above.
The super() method
What does the super() do in Python?
The super() method allows us to access the inherited methods that cascade to a class object.
In the earlier example, we’ve used the super() method in the constructor of the child class <Vehicle>. It is invoking the function of the base class <Taxi>.
How does the super() method work?
Just assume, if you have to invoke a method in the base class, i.e., vehicleInfo() defined in the child class, then you can use the following code.
super().vehicleInfo()Likewise, you can invoke the base class constructor from the sub (child) class __init__ using the below code.
super().__init__()Quick wrap up – Python Inheritance and OOP
In this tutorial, we covered “Python Inheritance” which is essential in object-oriented programming. Hence, it is utmost necessary that you are aware of how the inheritance works in Python.
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