INHERITANCE PART -2

Types of Inheritance

Different forms of Inheritance:

1. Single inheritance: When a child class inherits from only one parent class, it is called single inheritance. We saw an example above.

 

2. Multiple inheritance: When a child class inherits from multiple parent classes, it is called multiple inheritance.
Unlike Java and like C++, Python supports multiple inheritance. We specify all parent classes as a comma-separated list in the bracket.

# Python example to show the working of multiple  # inheritance classBase1(object):     def__init__(self):         self.str1 ="Geek1"         print("Base1")    classBase2(object):     def__init__(self):         self.str2 ="Geek2"                 print("Base2")    classDerived(Base1, Base2):     def__init__(self):                    # Calling constructors of Base1         # and Base2 classes         Base1.__init__(self)         Base2.__init__(self)         print("Derived")                defprintStrs(self):         print(self.str1, self.str2)             ob =Derived() ob.printStrs()

Output:

Base1

Base2

Derived

('Geek1', 'Geek2')

Output :

Base1

Base2

Derived

Geek1 True E101

 

3.  Multilevel inheritance: When we have a child and grandchild relationship.

 

# A Python program to demonstrate inheritance     # Base or Super class. Note object in bracket. # (Generally, object is made ancestor of all classes) # In Python 3.x "class Person" is  # equivalent to "class Person(object)" classBase(object):            # Constructor     def__init__(self, name):         self.name =name        # To get name     defgetName(self):         returnself.name       # Inherited or Sub class (Note Person in bracket) classChild(Base):            # Constructor     def__init__(self, name, age):         Base.__init__(self, name)         self.age =age        # To get name     defgetAge(self):         returnself.age    # Inherited or Sub class (Note Person in bracket) classGrandChild(Child):            # Constructor     def__init__(self, name, age, address):         Child.__init__(self, name, age)         self.address =address        # To get address     defgetAddress(self):         returnself.address            # Driver code g =GrandChild("Geek1", 23, "Noida")   print(g.getName(), g.getAge(), g.getAddress())

Output:

Geek1 23 Noida

 

4. Hierarchical inheritance More than one derived classes are created from a single base.

 

5. Hybrid inheritance: This form combines more than one form of inheritance. Basically, it is a blend of more than one type of inheritance.

Private members of parent class
We don’t always want the instance variables of the parent class to be inherited by the child class i.e. we can make some of the instance variables of the parent class private, which won’t be available to the child class.
We can make an instance variable by adding double underscores before its name. For example,

# Python program to demonstrate private members # of the parent class classC(object):        def__init__(self):               self.c =21                  # d is private instance variable                self.__d =42     classD(C):        def__init__(self):               self.e =84               C.__init__(self) object1 =D()    # produces an error as d is private instance variable print(object1.d)

Output :

  File "/home/993bb61c3e76cda5bb67bd9ea05956a1.py", line 16, in

print (D.d)                    

AttributeError: type object 'D' has no attribute 'd'

Since ‘d’ is made private by those underscores, it is not available to the child class ‘D’ and hence the error.