Python classmethod()

Normally to call a method of a class, we need to first create an instance or object of the class. But a class method is bound to the class, not to its objects, so the creation of the classmethod function returns the class method for a given function

classmethod(function) #where function is an name of function

classmethod() Parameters:

The classmethod() function takes only a single parameter

classmethod() Return Value

The return value or output of the method is a class method, which can be called without an instance of the class.

Examples of classmethod() method in Python

class Products:
getcode = ‘P36’

def getProductCode(cls):
print('The Product Code is:', cls.getcode)

# create printCode class method
Products.getProductCode = classmethod(Products .getProductCode ) 
Products.getProductCode ()
 

Output:

The Product Code is: P36

# random Person
class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    @classmethod
    def fromBirthYear(cls, name, birthYear):
        return cls(name, date.today().year - birthYear)

    def display(self):
        print(self.name + "'s age is: " + str(self.age))
 pers 19)
person.display()
 pers  1985)
person1.display()
 

Output:

Adam's age is: 19
John's age is: 31

from datetime import date

# random Person
class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    @staticmethod
    def fromFathersAge(name, fatherAge, fatherPersonAgeDiff):
        return Person(name, date.today().year - fatherAge + fatherPersonAgeDiff)

    @classmethod
    def fromBirthYear(cls, name, birthYear):
        return cls(name, date.today().year - birthYear)

    def display(self):
        print(self.name + "'s age is: " + str(self.age))

class Man(Person):
    sex = 'Male'

man = Man.fromBirthYear('John', 1985)
print(isinstance(man, Man))

man1 = Man.fromFathersAge('John', 1965, 20)
print(isinstance(man1, Man))
 

Output:

True
False