Python Classes/Objects - W3Schools

Almost everything in Python is an object, with its properties and methods. A Class is like an object constructor, or a "blueprint" for creating objects. 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AlmosteverythinginPythonisanobject,withitspropertiesandmethods. AClassislikeanobjectconstructor,ora"blueprint"forcreatingobjects. CreateaClass Tocreateaclass,usethekeywordclass: Example CreateaclassnamedMyClass,withapropertynamedx: classMyClass: x=5 TryitYourself» CreateObject NowwecanusetheclassnamedMyClasstocreateobjects: Example Createanobjectnamedp1,andprintthevalueofx: p1=MyClass()print(p1.x) TryitYourself» The__init__()Function Theexamplesaboveareclassesandobjectsintheirsimplestform,andare notreallyusefulinreallifeapplications. Tounderstandthemeaningofclasseswehavetounderstandthebuilt-in__init__() function. Allclasseshaveafunctioncalled__init__(),whichisalwaysexecutedwhen theclassisbeinginitiated. Usethe__init__()functiontoassignvaluestoobjectproperties,orother operationsthatarenecessarytodowhentheobject isbeingcreated: Example CreateaclassnamedPerson,usethe__init__()functiontoassignvalues fornameandage: classPerson: def__init__(self,name,age):    self.name=name   self.age=agep1=Person("John", 36) print(p1.name)print(p1.age) TryitYourself» Note:The__init__()functioniscalledautomaticallyeverytimetheclassisbeingusedtocreateanewobject. ObjectMethods Objectscanalsocontainmethods.Methodsinobjectsarefunctionsthat belongtotheobject. LetuscreateamethodinthePersonclass: Example Insertafunctionthatprintsagreeting,andexecuteitonthep1object: classPerson: def__init__(self,name,age):    self.name=name   self.age=age defmyfunc(self):    print("Hellomynameis"+self.name)p1=Person("John", 36)p1.myfunc() TryitYourself» Note:Theselfparameter isareferencetothecurrentinstanceoftheclass,andisusedtoaccessvariablesthatbelongtotheclass. TheselfParameter Theselfparameterisareferencetothe currentinstanceoftheclass,andisusedtoaccessvariablesthatbelongstotheclass. Itdoesnothavetobenamedself,youcan callitwhateveryoulike,butithastobethefirstparameterofanyfunction intheclass: Example Usethewordsmysillyobjectandabcinsteadofself: classPerson: def__init__(mysillyobject,name,age):    mysillyobject.name=name   mysillyobject.age=age defmyfunc(abc):    print("Hellomynameis"+abc.name)p1=Person("John", 36)p1.myfunc() TryitYourself» ModifyObjectProperties Youcanmodifypropertiesonobjectslikethis: Example Settheageofp1to40: p1.age=40 TryitYourself» DeleteObjectProperties Youcandeletepropertiesonobjectsbyusingthe delkeyword: Example Deletetheagepropertyfromthep1object: delp1.age TryitYourself» DeleteObjects Youcandeleteobjectsbyusingthedelkeyword: Example Deletethep1object: delp1 TryitYourself» ThepassStatement classdefinitionscannotbeempty,butif youforsomereasonhaveaclassdefinitionwithnocontent,putinthepassstatementtoavoidgettinganerror. Example classPerson: pass TryitYourself» TestYourselfWithExercises Exercise: CreateaclassnamedMyClass: MyClass: x=5 SubmitAnswer» StarttheExercise ❮Previous Next❯ NEW WejustlaunchedW3Schoolsvideos Explorenow COLORPICKER Getcertifiedbycompletingacoursetoday! w3schoolsCERTIFIED.2022 Getstarted CODEGAME PlayGame