Inheritance and Types in Python

Inheritance

Creating a new class from existing class is known as inheritance. The class from which features are inherited is known as base class and the class into which features are derived into is called derived class.

Syntax:

class derived-class(base class):
<class-suite>

Inheritance promotes reusability of code by reusing already existing classes.

Inheritance is used to implement is-a relationship between classes.

Following hierarchy is an example representing inheritance between classes:

vehicle-hierarchy

Single inheritance

When a derived class inherits only from syntax, the base class is called single inheritance. If it has one base class and one derived class it is called single inheritance.

Diagram

Syntax

class A: #parent class  
    #some code  
  
class b(A): #child class  
    #some code  

Example

class father:#parent class  
  def father_name(self):  
     print("my father name is selvaraj")  
  
class son(father):#child class  
  pass  
  
obj_father= father()#object for father class.  
obj_son=son()#object for son class.  
  
obj_son.father_name()# you access son class to father class. 

Output

Multilevel inheritance

Multiple inheritance is the concept where a subclass inherits properties from multiple base classes. It has one base class and two (or) more derived classes called multilevel inheritance.

Diagram

Syntax

class A: #parent class  
    #some code  
  
class B(A): #child class  
    #some code  
  
class C(B): #child class  
    #some code  

Example

class g_father:#parent class  
  def g_father_name(self):  
     print("my father name is ramasamy")  
  
class father(g_father):#child class  
  def father_name(self):  
     print("my father name is selvaraj")  
  
class son(father):#child class  
  def son_name(self):  
     print("my name is surya")  
  
  
obj_g_father= father()#object for g_father class.  
obj_father= father()#object for father class.  
obj_son=son()#object for son class.  
  
obj_son.g_father_name()# you access son class to g_father class.  
obj_son.father_name()# you access son class to father class.  
obj_son.son_name()# you access same class. 

Output

Multiple inheritance

Multiple inheritance is the concept where a subclass inherits properties from multiple base classes. If it has two base classes and one derived class it is called multilevel inheritance.

Diagram

Syntax

class A: #parent class  
    #some code  
  
class B(A): #parent class  
    #some code  
  
class C (A, B): #child class  
    #some code  

Example

class father:#parent class  
  def father_name(self):  
     print("my father name is selvaraj")  
  
class mother:#parent class  
  def mother_name(self):  
     print("my father name is jayanthi")  
  
class son(mother,father):#child class  
  pass  
  
obj_father= father()#object for father class.  
obj_mother=mother()#object for mother class.  
obj_son=son()#object for son class.  
  
obj_son.father_name()# you access son class to father class.  
obj_son.mother_name()# you access son class to mother class.  
  
  
#obj_mother.father_name()\\This statement did not work because mother and father are parents. 

Output

Hierarchical Inheritance

This inheritance allows a class to host as a parent class for more than one child class or subclass. This provides a benefit of sharing the functioning of methods with multiple child classes, hence avoiding code duplication.

#parent class
class Parent:
  def fun1(self):
print(“Hey there, you are in the parent class”)

#child class 1
class child1(Parent):
  def fun2(self):
print(“Hey there, you are in the child class 1”)

#child class 2
class child2(Parent):
  def fun3(self):
print(“Hey there, you are in the child class 2”)

#child class 3
class child3(Parent):
  def fun4(self):
print(“Hey there, you are in the child class 3”)

# main program
child_obj1 = child3()
child_obj2 = child2()
child_obj3 = child1()
child_obj1.fun1()
child_obj1.fun4()
child_obj2.fun1()
child_obj2.fun3()
child_obj3.fun1()
child_obj3.fun2()

In the above code, we have a single parent class and multiple child classes inheriting the same parent class. Now all the child classes can access the methods and variables of the parent class. We’ve created a “Parent” class and 3 child classes “child1”, “child2”, “child3”, which inherits the same parent class “Parent”.

Hybrid Inheritance:

Inheritance consisting of multiple types of inheritance is called hybrid inheritance.

class School:

     def func1(self):

         print("This function is in school.")

class Student1(School):

     def func2(self):

         print("This function is in student 1. ")

class Student2(School):

     def func3(self):

         print("This function is in student 2.")

class Student3(Student1, School):

     def func4(self):

         print("This function is in student 3.")

# Driver's code

object = Student3()

object.func1()

object.func2()

Output:
This function is in school.
This function is in student 1.

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