Inheritance In Python

What is Inheritance in Python?

Inheritance is one of the most important and powerful features of object-oriented programming. Inheritance refers to the property in which a class can inherit properties of another class that is the derived class can access all the properties, functions, and data members of the base class from which it has been inherited. To compare the feature with real-time, children get characteristics and behaviors inherited from their parents. Inheritance in Python is provided for the same purpose as explained.

Table Of Contents

Advantages of Inheritance:

  • Reusability of code – since one can inherit from the base class, the efficiency of the code increases and the size of the code also decreases instead of rewriting the code.
  • It forms a chain process i.e. if a child class is inherited from the base class, and if a new class is inherited from the child class, then all the properties of the base class will also be present in the new class.

Syntax:

Class base_class:
     Body of base_class
Class child_class (base_class):
     Body of child_class

Example

class Parent:
     def __init__(self , fname, fage):
          self.firstname = fname
          self.age = fage
     def view(self):
         print(self.firstname , self.age)
class Child(Parent):
     def __init__(self , fname , fage):
          Parent.__init__(self, fname, fage)
          self.lastname = "Machine Learning"
     def view(self):
          print(self.firstname ," came ",  self.age , " years ago. Today, python is the base for" , self.lastname)
object = Child("Python" , '28')
object.view()
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Output

Python came  28  years ago. Today, python is the base for Machine Learning
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Types of inheritance:

  • Single inheritance
  • Multiple inheritance
  • Multilevel inheritance
  • Hierarchical inheritance
  • Hybrid inheritance

Single inheritance

In single inheritance, only one child class can be inherited from the base class. Not more than one class can be used for inheritance.

Syntax:

Class base_class:
     Body of base_class
Class child_class (base_class):
     Body of child_class

Example

class Base:
     def __init__(self , fname, fage):
          self.firstname = fname
          self.age = fage
     def view(self):
         print(self.firstname , self.age)
class Child(Base):
     def __init__(self , fname , fage):
          Base.__init__(self, fname, fage)
          self.lastname = "Machine Learning"
     def view(self):
          print(self.firstname ," is ",  self.age , " years old and he is a pro in " , self.lastname)
object = Child("Raj" , '21')
object.view()
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Output

Raj  is  21  years old and he is a pro in  Machine Learning
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Multiple inheritance

In multiple inheritance, a child class can be inherited from more than one base class. Unlike single inheritance, there is no restriction on the number of base classes for inheriting the properties.

Syntax:

Class Base1():
   Body of base1
Class of Base2():
   Body of base2
Class Child (Base1,Base2):
   Body of child

Example

class mom:
    mom_name = ""
    def mom(self):
        print(self.mom_name)
class dad:
    dad_name = ""
    def dad(self):
        print(self.dad_name)
class daughter(mom,dad):
    def parents(self):
        print("Father's name: ",self.dad_name)
        print("Mother's name: ",self.mom_name)
object=daughter()
object.dad_name="raj"
object.mom_name="nandhini"
object.parents()
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Output

Father's name:  raj
Mother's name:  nandhini
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Multilevel inheritance

The multilevel inheritance is like a chain process. In this type, a class is derived from a base class and it becomes a base class for another class that is another new class is derived from this derived class.

Syntax:

Class Base:
    Body of base class
Class Derived1 (Base):
   Body of derived1 class
Class Derived2 (Derived1):
  Body of derived2 class

Example

class Granddad:
 
    def __init__(self, grandfather_name):
        self.grandfather_name = grandfather_name
class dad(Granddad):
    def __init__(self, father_name, grandfather_name):
        self.father_name = father_name
 
        Granddad.__init__(self, grandfather_name)
class Son(dad):
    def __init__(self,son_name, father_name, grandfather_name):
        self.son_name = son_name
 
        dad.__init__(self, father_name, grandfather_name)
 
    def print_name(self):
        print('Grandfather name :', self.grandfather_name)
        print("Father name :", self.father_name)
        print("Son name :", self.son_name)
 
s1 = Son('Lucky', 'Raj', 'Kamal')
s1.print_name()
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Output

Grandfather name : Kamal
Father name : Raj
Son name : Lucky
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Hierarchical inheritance

In hierarchical inheritance from a single base class, we can inherit multiple derived classes. There is no restriction on the number of derived classes.

Syntax:

Class Base:
   Body of base class
Class Derived1 (Base) :
   Body of derived1 class
Class Derived2 (Base) :
   Body of derived2 class

Example

class Details:
    def __init__(self):
        self.__id="<No Id>"
        self.__name="<No Name>"
        self.__gender="<No Gender>"
    def setData(self,id,name,gender):
        self.__id=id
        self.__name=name
        self.__gender=gender
    def showData(self):
        print("Id: ",self.__id)
        print("Name: ", self.__name)
        print("Gender: ", self.__gender)
class Employee(Details): #Inheritance
    def __init__(self):
        self.__company="<No Company>"
        self.__dept="<No Dept>"
    def setEmployee(self,id,name,gender,comp,dept):
        self.setData(id,name,gender)
        self.__company=comp
        self.__dept=dept
    def showEmployee(self):
        self.showData()
        print("Company: ", self.__company)
        print("Department: ", self.__dept)
class Doctor(Details): #Inheritance
    def __init__(self):
        self.__hospital="<No Hospital>"
        self.__dept="<No Dept>"
    def setEmployee(self,id,name,gender,hos,dept):
        self.setData(id,name,gender
 self.__hospital=hos
        self.__dept=dept
    def showEmployee(self):
        self.showData()
        print("Hospital: ", self.__hospital)
        print("Department: ", self.__dept)
def main():
    print("Employee Object")
    e=Employee()
    e.setEmployee(1,"Prem Sharma","Male","gmr","excavation")
    e.showEmployee()
    print("\nDoctor Object")
    d = Doctor()
    d.setEmployee(1, "pankaj", "male", "aiims", "eyes")
    d.showEmployee()
if __name__=="__main__":
    main()
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Output

Employee Object
Id:  1
Name:  Prem Sharma
Gender:  Male
Company:  gmr
Department:  excavation
Doctor Object
Id:  1
Name:  pankaj
Gender:  male
Hospital:  aiims
Department:  eyes
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Hybrid inheritance

The hybrid inheritance is a combination of other types of inheritance. Mostly it is a combination of multilevel and multiple inheritance. This type of inheritance is not much used.

In general, multiple and multilevel inheritance is widely used in real-time problems. Single inheritance is used for simple applications.

Check this video for more:

Video credits– Edureka

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