61 - Inheritance in Python

When a class derives from another class,
The child class will inherit all the public and protected properties and methods from the parent class.
In addition, it can have its own properties and methods,this is called as inheritance.

Syntax

class ParentClass:
  Body of base class
  
class Derived/ChildClass(ParentClass):
  Body of derived class
  • Derived class inherits features from the base/Parent class where new features can be added to it.
    This results in re-usability of code.

Types of inheritance:

  1. Single inheritance
  2. Multiple inheritance
  3. Multilevel inheritance
  4. Hierarchical Inheritance
  5. Hybrid Inheritance
  • We will see the explanation and example of each type of inheritance in the later tutorials

Single Inheritance:

Single inheritance enables a derived class to inherit properties from a single parent class, thus enabling code re-usability and the addition of new features to existing code.

Example:

class Parent:
    def func1(self):
        print("This function is in parent class.")
 
class Child(Parent):
    def func2(self):
        print("This function is in child class.")
 
object = Child()
object.func1()
object.func2()

# Output:
This function is in parent class.
This function is in child class.

Multiple Inheritance:

When a class can be derived from more than one base class this type of inheritance is called multiple inheritances. In multiple inheritances, all the features of the base classes are inherited into the derived class.

Example:

class Mother:
    mothername = ""
 
    def mother(self):
        print(self.mothername)
 
 
class Father:
    fathername = ""
 
    def father(self):
        print(self.fathername)
 
 
class Son(Mother, Father):
    def parents(self):
        print("Father name is :", self.fathername)
        print("Mother :", self.mothername)
s1 = Son()
s1.fathername = "Mommy"
s1.mothername = "Daddy"
s1.parents()


# Output:
Father name is : Mommy
Mother name is : Daddy

Multilevel Inheritance :

In multilevel inheritance, features of the base class and the derived class are further inherited into the new derived class. This is similar to a relationship representing a child and a grandfather.

Example:

class Grandfather:
 
    def __init__(self, grandfathername):
        self.grandfathername = grandfathername
 
 
class Father(Grandfather):
    def __init__(self, fathername, grandfathername):
        self.fathername = fathername
        Grandfather.__init__(self, grandfathername)
class Son(Father):
    def __init__(self, sonname, fathername, grandfathername):
        self.sonname = sonname
        Father.__init__(self, fathername, grandfathername)
 
    def print_name(self):
        print('Grandfather name :', self.grandfathername)
        print("Father name :", self.fathername)
        print("Son name :", self.sonname)
s1 = Son('Prince', 'Rampal', 'Lal mani')
print(s1.grandfathername)
s1.print_name()


# Output:
George
Grandfather name : George
Father name : Philip
Son name : Charles

Hierarchical Inheritance:

When more than one derived class are created from a single base this type of inheritance is called hierarchical inheritance. In this program, we have a parent (base) class and two child (derived) classes.

Example:

class Parent:
    def func1(self):
        print("This function is in parent class.")

class Child1(Parent):
    def func2(self):
        print("This function is in child 1.")
      
class Child2(Parent):
    def func3(self):
        print("This function is in child 2.")
 
object1 = Child1()
object2 = Child2()
object1.func1()
object1.func2()
object2.func1()
object2.func3()


# Output:
This function is in parent class.
This function is in child 1.
This function is in parent class.
This function is in child 2.

Hybrid Inheritance:

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

Example

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.")
 
object = Student3()
object.func1()
object.func2()


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

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