what is the difference between classmethod amd static method?

Answer 1

Class methods are passed the calling class, static methods aren't

Answer 2

instance method -> implicit first argument is an instance of the class

class method -> implicit first argument is the class

static method -> no implicit first arguments

class Cls:
def instance_meth(self, a):
print(self, a)

@classmethod
def class_meth(cls, a):
print(cls, a)

@staticmethod
def static_meth(a):
print(a)

c = Cls()

c.instance_meth(1)
#Cls.instance_meth(1) #TypeError

c.class_meth(2)
Cls.class_meth(3)

c.static_meth(4)
Cls.static_meth(5)

Answer 3

Basically, there are instance methods, class methods and static methods.

An instance method is always linked to a specific instance of a class. The instance is usually referenced with the variable "self". In a Person class, an instance method "get_age" could look like this:

class Person(object):
def __init__(self, name, age):
self._name = name
self._age = age

def get_age(self): # instance method
return self._age

You can create a new Person instance like this:

p1 = Person('John', 85)

and get its age like this:

print(p1.get_name()) # 85

A class method is linked to the class itself and returns an instance of the class. It usually takes "cls" as a reference to the class.

Let's say you want to create a new Person instance from a string like "Hubert, 123". Your class method could look like this:

@classmethod
def from_string(cls, string):
name, age = string.split(',')
age = int(age)
return cls(name, age)

You can call the class method like this:

p2 = Person.from_string('Hubert, 123')

The class method will take the string "Hubert, 123", split it into "Hubert" and 123 and return a new Person instance with these parameters.

A static method is linked neither to a specific instance of the class nor to the class itself, hence it doesn't take any parameters like "self" or "cls".

An instance method that checks if a string contains a valid name and age for a Person instance could look like this:

@staticmethod
def check_valid_string(string):
import re
name_pattern = re.compile(r'^([A-Z][a-z]+),\s*(\d+)#x27;)
m = name_pattern.match(string)
if m:
name, age = m.groups()
age = int(age)
if not 0 <= age <= 120:
return False
else:
return False
return True

You can call the static method like this:

print(Person.check_valid_string('Peter, 45')) # True
print(Person.check_valid_string('Doris, 546')) # False

Answer 4

class method are calling the class ........................................ select this option

Answer 5

Question : What is the difference between a class method and a static method?
answer : Class methods are inherited, static methods aren't