In the previous fact, we have seen that Python doesn’t have the static keyword. All variables that are assigned a value in the class declaration are class variables.
We should be careful when changing the value of a class variable. If we try to change a class variable using an object, a new instance (or non-static) variable for that particular object is created and this variable shadows the class variables. Below is a Python program to demonstrate the same.
Python3
# Class for Computer Science Studentclass CSStudent: stream = 'cse' # Class Variable def __init__(self, name, roll): self.name = name self.roll = roll# Driver program to test the functionality# Creating objects of CSStudent classa = CSStudent("Geek", 1)b = CSStudent("Nerd", 2)print ("Initially")print ("a.stream =", a.stream )print ("b.stream =", b.stream )# This thing doesn't change class(static) variable# Instead creates instance variable for the object# 'a' that shadows class member.a.stream = "ece"print ("\nAfter changing a.stream")print ("a.stream =", a.stream )print ("b.stream =", b.stream ) |
Output:
Initially a.stream = cse b.stream = cse After changing a.stream a.stream = ece b.stream = cse
We should change class variables using class names only.
Python3
# Program to show how to make changes to the# class variable in Python# Class for Computer Science Studentclass CSStudent: stream = 'cse' # Class Variable def __init__(self, name, roll): self.name = name self.roll = roll# New object for further implementationa = CSStudent("check", 3)print "a.stream =", a.stream# Correct way to change the value of class variableCSStudent.stream = "mec"print "\nClass variable changes to mec"# New object for further implementationb = CSStudent("carter", 4)print "\nValue of variable steam for each object"print "a.stream =", a.streamprint "b.stream =", b.stream |
Output:
a.stream = cse Class variable changes to mec Value of variable steam for each object a.stream = mec b.stream = mec
This article is contributed by Nikhil Kumar Singh. If you like Lazyroar and would like to contribute, you can also write an article and mail your article to review-team@neveropen.co.za. See your article appearing on the Lazyroar main page and help other Geeks.
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