When to use class methods in python

In Python, class methods are defined using the decorator @classmethod.

Let’s look directly at the example. (Recommended learning: Python video tutorial)

class Kls(object):
    num_inst = 0

    def __init__(self):
        Kls.num_inst = Kls.num_inst + 1

    @classmethod
    def get_no_of_instance(cls):
        return cls.num_inst


ik1 = Kls()
ik2 = Kls()

print ik1.get_no_of_instance()
print Kls.get_no_of_instance()

Class method is used to simulate the situation where java defines multiple constructors.

Since there can only be one initialization method in a python class, the class cannot be initialized according to different situations.

coding:utf-8
class Book(object):
def __init__(self, title):
self.title = title
   @classmethod
def class_method_create(cls, title):
book = cls(title=title)
return book
   @staticmethod
def static_method_create(title):
book= Book(title)
return book
book1 = Book("use instance_method_create book instance")
book2 = Book.class_method_create("use class_method_create book instance")
book3 = Book.static_method_create("use static_method_create book instance")
print(book1.title)
print(book2.title)
print(book3.title)

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