Python Object Oriented Programming - Programiz

The concept of OOP in Python focuses on creating reusable code. This concept is also known as DRY (Don't Repeat Yourself). In Python, the concept of OOP follows ... CourseIndex ExploreProgramiz Python JavaScript SQL C C++ Java Kotlin Swift C# DSA LearnPythonpractically andGetCertified. ENROLL PopularTutorials GettingStartedWithPython PythonifStatement whileLoopinPython PythonLists DictionariesinPython StartLearningPython PopularExamples Addtwonumbers Checkprimenumber Findthefactorialofanumber PrinttheFibonaccisequence Checkleapyear ExplorePythonExamples ReferenceMaterials Built-inFunctions ListMethods DictionaryMethods StringMethods Viewall LearningPaths Challenges LearnPythonInteractively TryforFree Courses BecomeaPythonMaster BecomeaCMaster BecomeaJavaMaster ViewallCourses Python JavaScript SQL C C++ Java Kotlin Swift C# DSA LearnPythonpractically andGetCertified. ENROLLFORFREE! 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PopularExamples Addtwonumbers Checkprimenumber Findthefactorialofanumber PrinttheFibonaccisequence Checkleapyear AllPythonExamples LearnPythonInteractively PythonIntroduction GettingStarted KeywordsandIdentifier Statements&Comments PythonVariables PythonDataTypes PythonTypeConversion PythonI/OandImport PythonOperators PythonNamespace PythonFlowControl Pythonif...else PythonforLoop PythonwhileLoop Pythonbreakandcontinue PythonPass PythonFunctions PythonFunction FunctionArgument PythonRecursion AnonymousFunction Global,LocalandNonlocal PythonGlobalKeyword PythonModules PythonPackage PythonDatatypes PythonNumbers PythonList PythonTuple PythonString PythonSet PythonDictionary PythonFiles PythonFileOperation PythonDirectory PythonException ExceptionHandling User-definedException PythonObject&Class PythonOOP PythonClass PythonInheritance MultipleInheritance OperatorOverloading PythonAdvancedTopics PythonIterator PythonGenerator PythonClosure PythonDecorators PythonProperty PythonRegEx PythonExamples PythonDateandtime PythondatetimeModule Pythondatetime.strftime() Pythondatetime.strptime() Currentdate&time Getcurrenttime Timestamptodatetime PythontimeModule Pythontime.sleep() RelatedTopics PolymorphisminPython PythonObjectsandClasses PythonInheritance Pythonsuper() Pythonobject() PythonDocstrings PythonObjectOrientedProgramming Inthistutorial,you’lllearnaboutObject-OrientedProgramming(OOP)inPythonanditsfundamentalconceptwiththehelpofexamples. Video:Object-orientedProgramminginPython ObjectOrientedProgramming Pythonisamulti-paradigmprogramminglanguage.Itsupportsdifferentprogrammingapproaches. Oneofthepopularapproachestosolveaprogrammingproblemisbycreatingobjects.ThisisknownasObject-OrientedProgramming(OOP). Anobjecthastwocharacteristics: attributes behavior Let'stakeanexample: Aparrotisanobject,asithasthefollowingproperties: name,age,colorasattributes singing,dancingasbehavior TheconceptofOOPinPythonfocusesoncreatingreusablecode.ThisconceptisalsoknownasDRY(Don'tRepeatYourself). InPython,theconceptofOOPfollowssomebasicprinciples: Class Aclassisablueprintfortheobject. Wecanthinkofclassasasketchofaparrotwithlabels.Itcontainsallthedetailsaboutthename,colors,sizeetc.Basedonthesedescriptions,wecanstudyabouttheparrot.Here,aparrotisanobject. Theexampleforclassofparrotcanbe: classParrot: pass Here,weusetheclasskeywordtodefineanemptyclassParrot.Fromclass,weconstructinstances.Aninstanceisaspecificobjectcreatedfromaparticularclass. Object Anobject(instance)isaninstantiationofaclass.Whenclassisdefined,onlythedescriptionfortheobjectisdefined.Therefore,nomemoryorstorageisallocated. Theexampleforobjectofparrotclasscanbe: obj=Parrot() Here,objisanobjectofclassParrot. Supposewehavedetailsofparrots.Now,wearegoingtoshowhowtobuildtheclassandobjectsofparrots. Example1:CreatingClassandObjectinPython classParrot: #classattribute species="bird" #instanceattribute def__init__(self,name,age): self.name=name self.age=age #instantiatetheParrotclass blu=Parrot("Blu",10) woo=Parrot("Woo",15) #accesstheclassattributes print("Bluisa{}".format(blu.__class__.species)) print("Wooisalsoa{}".format(woo.__class__.species)) #accesstheinstanceattributes print("{}is{}yearsold".format(blu.name,blu.age)) print("{}is{}yearsold".format(woo.name,woo.age)) Output Bluisabird Wooisalsoabird Bluis10yearsold Woois15yearsold Intheaboveprogram,wecreatedaclasswiththenameParrot.Then,wedefineattributes.Theattributesareacharacteristicofanobject. Theseattributesaredefinedinsidethe__init__methodoftheclass.Itistheinitializermethodthatisfirstrunassoonastheobjectiscreated. Then,wecreateinstancesoftheParrotclass.Here,bluandwooarereferences(value)toournewobjects. Wecanaccesstheclassattributeusing__class__.species.Classattributesarethesameforallinstancesofaclass.Similarly,weaccesstheinstanceattributesusingblu.nameandblu.age.However,instanceattributesaredifferentforeveryinstanceofaclass. Tolearnmoreaboutclassesandobjects,gotoPythonClassesandObjects Methods Methodsarefunctionsdefinedinsidethebodyofaclass.Theyareusedtodefinethebehaviorsofanobject. Example2:CreatingMethodsinPython classParrot: #instanceattributes def__init__(self,name,age): self.name=name self.age=age #instancemethod defsing(self,song): return"{}sings{}".format(self.name,song) defdance(self): return"{}isnowdancing".format(self.name) #instantiatetheobject blu=Parrot("Blu",10) #callourinstancemethods print(blu.sing("'Happy'")) print(blu.dance()) Output Blusings'Happy' Bluisnowdancing Intheaboveprogram,wedefinetwomethodsi.esing()anddance().Thesearecalledinstancemethodsbecausetheyarecalledonaninstanceobjecti.eblu. Inheritance Inheritanceisawayofcreatinganewclassforusingdetailsofanexistingclasswithoutmodifyingit.Thenewlyformedclassisaderivedclass(orchildclass).Similarly,theexistingclassisabaseclass(orparentclass). Example3:UseofInheritanceinPython #parentclass classBird: def__init__(self): print("Birdisready") defwhoisThis(self): print("Bird") defswim(self): print("Swimfaster") #childclass classPenguin(Bird): def__init__(self): #callsuper()function super().__init__() print("Penguinisready") defwhoisThis(self): print("Penguin") defrun(self): print("Runfaster") peggy=Penguin() peggy.whoisThis() peggy.swim() peggy.run() Output Birdisready Penguinisready Penguin Swimfaster Runfaster Intheaboveprogram,wecreatedtwoclassesi.e.Bird(parentclass)andPenguin(childclass).Thechildclassinheritsthefunctionsofparentclass.Wecanseethisfromtheswim()method. Again,thechildclassmodifiedthebehavioroftheparentclass.WecanseethisfromthewhoisThis()method.Furthermore,weextendthefunctionsoftheparentclass,bycreatinganewrun()method. Additionally,weusethesuper()functioninsidethe__init__()method.Thisallowsustorunthe__init__()methodoftheparentclassinsidethechildclass. Encapsulation UsingOOPinPython,wecanrestrictaccesstomethodsandvariables.Thispreventsdatafromdirectmodificationwhichiscalledencapsulation.InPython,wedenoteprivateattributesusingunderscoreastheprefixi.esingle_ordouble__. Example4:DataEncapsulationinPython classComputer: def__init__(self): self.__maxprice=900 defsell(self): print("SellingPrice:{}".format(self.__maxprice)) defsetMaxPrice(self,price): self.__maxprice=price c=Computer() c.sell() #changetheprice c.__maxprice=1000 c.sell() #usingsetterfunction c.setMaxPrice(1000) c.sell() Output SellingPrice:900 SellingPrice:900 SellingPrice:1000 Intheaboveprogram,wedefinedaComputerclass. Weused__init__()methodtostorethemaximumsellingpriceofComputer.Here,noticethecode c.__maxprice=1000 Here,wehavetriedtomodifythevalueof__maxpriceoutsideoftheclass.However,since__maxpriceisaprivatevariable,thismodificationisnotseenontheoutput. Asshown,tochangethevalue,wehavetouseasetterfunctioni.esetMaxPrice()whichtakespriceasaparameter. Polymorphism Polymorphismisanability(inOOP)touseacommoninterfaceformultipleforms(datatypes). Suppose,weneedtocolorashape,therearemultipleshapeoptions(rectangle,square,circle).Howeverwecouldusethesamemethodtocoloranyshape.ThisconceptiscalledPolymorphism. Example5:UsingPolymorphisminPython classParrot: deffly(self): print("Parrotcanfly") defswim(self): print("Parrotcan'tswim") classPenguin: deffly(self): print("Penguincan'tfly") defswim(self): print("Penguincanswim") #commoninterface defflying_test(bird): bird.fly() #instantiateobjects blu=Parrot() peggy=Penguin() #passingtheobject flying_test(blu) flying_test(peggy) Output Parrotcanfly Penguincan'tfly Intheaboveprogram,wedefinedtwoclassesParrotandPenguin.Eachofthemhaveacommonfly()method.However,theirfunctionsaredifferent. Tousepolymorphism,wecreatedacommoninterfacei.eflying_test()functionthattakesanyobjectandcallstheobject'sfly()method.Thus,whenwepassedthebluandpeggyobjectsintheflying_test()function,itraneffectively. KeyPointstoRemember: Object-OrientedProgrammingmakestheprogrameasytounderstandaswellasefficient. Sincetheclassissharable,thecodecanbereused. Dataissafeandsecurewithdataabstraction. Polymorphismallowsthesameinterfacefordifferentobjects,soprogrammerscanwriteefficientcode. TableofContents IntroductiontoOOP inPython Class Object Methods Inheritance Encapsulation Polymorphism KeyPointstoRemember PreviousTutorial: User-definedException NextTutorial: PythonClass Shareon: Didyoufindthisarticlehelpful? Sorryaboutthat. Howcanweimproveit? Feedback* Leavethisfieldblank RelatedTutorialsPythonTutorialPolymorphisminPythonPythonTutorialPythonObjectsandClassesPythonTutorialPythonInheritancePythonLibraryPythonsuper() TryPROforFREE LearnPythonInteractively