INHERITANCE IN PYTHON

The concept of using properties of one class into another class without creating object of that class explicitly is known as a Inheritance. A class which is extended by another class is known as ‘super class’. A class which is extending another class is known as ‘sub class’. Both super class properties and sub class properties can be accessed through sub class reference variable.

Example –

class A:
    def m1(self):
        self.i=100
class B(A):
    def m2(self):
        self.j=200
B1=B()
B1.m1()
B1.m2()
print B1.i
print B1.j

Output –

100

200

Super class properties directly we can use within the subclass.

Example –

class A:
    def m1(self):
        self.i=100
class B(A):
    def m2(self):
        self.j=200
    def display(self):
        print self.i
        print self.j
B1=B()
B1.m1()
B1.m2()
B1.display()

Output –

100

200

Example –

class Parent:
    parentAttr=100
    def __init__(self):
        print 'calling parent constructor'
    def parentMethod(self):
        print 'calling parent method'
    def setAttr(self,attr):
        Parent.parentAttr=attr
    def getAttr(self):
        print 'Parent Attribute',Parent.parentAttr
class Child(Parent):
    def __init__(self):
        print 'calling child constructor'
    def childMethod(self):
        print 'calling child method'
P=Parent()
P.parentMethod()
P.setAttr(200)
P.getAttr()
C=Child()
C.childMethod()
C.parentMethod()
C.setAttr(300)
C.getAttr()

Output –

calling parent constructor

calling parent method

Parent Attribute 200

calling child constructor

calling child method

calling parent method

Parent Attribute 300

Example –

class A:
    def __init__(self):
        print 'in constructor of A'
class B(A):
    def m1(self):
        print 'in m1 of B'
B1=B()
B1.m1()

Output –

in constructor of A

in m1 of B

Example –

class A:
    def m1(self):
        print A.__bases__
class B(A):
    def m2(self):
        print B.__bases__
B1=B()
B1.m1()
B1.m2()

Output –

()

(<class __main__.A at 0x028BEC00>,)