Python inheritance
- 1. Inheritance isthe capabilityof one classtoderive orinheritthe propertiesfromanotherclass.The benefitsof inheritance are: It representsreal-worldrelationshipswell. It providesreusabilityof acode.We don’thave to write the same code againand again.Also,itallowsusto add more featurestoa class withoutmodifyingit. It istransitive innature,whichmeansthatif classB inheritsfromanotherclassA,thenall the subclassesof B would automaticallyinheritfromclassA. # A Pythonprogram to demonstrate inheritance # Base or Superclass.Note objectinbracket. # (Generally,objectismade ancestorof all classes) # InPython3.x "classPerson"is # equivalentto"classPerson(object)" classPerson(object): # Constructor def __init__(self,name): self.name=name # To get name def getName(self): returnself.name # To checkif thispersonisan employee def isEmployee(self): returnFalse # InheritedorSubclass(Note Personinbracket) classEmployee(Person): # Here we returntrue def isEmployee(self): returnTrue # Drivercode emp= Person("Geek1") # AnObjectof Person print(emp.getName(),emp.isEmployee()) emp= Employee("Geek2") #An Objectof Employee print(emp.getName(),emp.isEmployee())
- 2. ============== Subclassing(Callingconstructorof parentclass) A childclassneedstoidentifywhichclassisitsparentclass.Thiscan be done bymentioningthe parent classname in the definitionof the childclass. Eg: class subclass_name (superclass_name): _ _ _ _ _ _ # Pythoncode to demonstrate howparentconstructors # are called. # parentclass classPerson( object): # __init__ isknownas the constructor def __init__(self,name,idnumber): self.name =name self.idnumber=idnumber def display(self): print(self.name) print(self.idnumber) # childclass classEmployee( Person): def __init__(self,name,idnumber,salary,post): self.salary=salary self.post=post # invokingthe __init__of the parentclass Person.__init__(self,name,idnumber) # creationof an objectvariable oran instance a = Employee('Rahul',886012, 200000, "Intern") # callingafunctionof the class Personusingitsinstance a.display() ==== Differentformsof Inheritance: 1. Single inheritance:Whenachildclassinheritsfromonlyone parentclass,itiscalledsingle inheritance.We sawan example above.
- 3. 2. Multiple inheritance:Whenachildclassinheritsfrommultipleparentclasses,itiscalledmultiple inheritance. Unlike Javaand like C++,Pythonsupportsmultipleinheritance.We specifyall parentclassesasacomma-separated listinthe bracket. # Pythonexampletoshowthe workingof 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): # Callingconstructorsof Base1 # and Base2 classes Base1.__init__(self) Base2.__init__(self) print("Derived") def printStrs(self): print(self.str1,self.str2) ob = Derived() ob.printStrs() ======= 3. Multilevel inheritance:Whenwe have achildand grandchild relationship. # A Pythonprogramto demonstrate inheritance # Base or Superclass.Note objectinbracket. # (Generally,objectismade ancestorof all classes) # InPython3.x "classPerson"is # equivalentto"classPerson(object)" classBase(object): # Constructor
- 4. def __init__(self,name): self.name=name # To get name def getName(self): returnself.name # InheritedorSubclass(Note Personinbracket) classChild(Base): # Constructor def __init__(self,name,age): Base.__init__(self,name) self.age =age # To get name def getAge(self): returnself.age # InheritedorSubclass(Note Personinbracket) classGrandChild(Child): # Constructor def __init__(self,name,age,address): Child.__init__(self,name,age) self.address=address # To get address def getAddress(self): returnself.address # Drivercode g = GrandChild("Geek1",23,"Noida") print(g.getName(), g.getAge(),g.getAddress())