Answers for "what is classmethod in python"

what is a class in python

Classes are blueprint used to construct objects

what is a class in python

A class is a block of code that holds various functions. Because they
are located inside a class they are named methods but mean the samne
thing. In addition variables that are stored inside a class are named 
attributes. The point of a class is to call the class later allowing you 
to access as many functions or (methods) as you would like with the same
class name. These methods are grouped together under one class name due
to them working in association with eachother in some way.

python classmethod

class point:
	def __init__(self, x, y):
    	self.x = x
        self.y = y
        
    @classmethod
    def zero(cls):
    	return cls(0, 0)
        
    def print(self):
    	print(f"x: {self.x}, y: {self.y}")
        
p1 = point(1, 2)
p2 = point().zero()
print(p1.print())
print(p2.print())

python classmethod

# classmethod example
In [20]: class MyClass:
    ...:     @classmethod
    ...:     def set_att(cls, value):
    ...:         cls.att = value
    ...:

In [21]: MyClass.set_att(1)

In [22]: MyClass.att
Out[22]: 1

In [23]: obj = MyClass()

In [24]: obj.att
Out[24]: 1

In [25]: obj.set_att(3)

In [26]: obj.att
Out[26]: 3

In [27]: MyClass.att
Out[27]: 3

python class with function @classmethod

import numpy as np 

class Unknown:
    def __init__(self, p1, p2, p3, p4):
        self.p1 = p1
        self.p2 = p2
        self.p3 = p3
        self.p4 = p4

    def random_func(self, p5):
        '''Function that return an array from a range,
        with specified shape, and name'''
        step1 = np.array(np.arange(self.p1)).reshape((self.p2,self.p3))
        step2 = self.p4
        print(step2)
        print('Printing p5 =>', p5)
        return step1

    @classmethod
    def a_class_method(self, p6):
        print(f'This is a class method: {p6}')
        
        

#PREPARE PARAMS 
# cust_arr = random_func(self.p1, self.p2, self.p3, self.p4)
params = {'p1':12, 'p2':3, 'p3':4, 'p4':'Creating customized array with params'}

#INSTANCIATE
here = Unknown(**params)#16, 4, 4, 'This actually work too!')
here.random_func('This is P5')
Unknown.a_class_method('P6 value is now used !')