1. Differences on parameters
Instance Methods: Instance methods are defined with at least one formal parameter ---> the instance object, usually self.
Class Methods: Class methods are defined with at least one formal parameter ---> the class object, usually cls.
Static Methods: Static methods can be defined without formal parameters.
2. On the difference between adding decorators when defining methods
Instance method: no need to add decorators
Class methods: need to add decorators ----> @classmethod
Static methods: need to add decorators ---> @staticmethod
3. Call:
1. Instance methods can be called directly through the object
2. But when you call it by class name, you need to create an object and pass the object in when you pass the parameter
3. Class methods can be called directly through the class name or through an object
4. Static methods can be called directly through the class name or through an object
4. Supplementary
1. Static methods cannot be inherited
2. Class methods cannot access instance variables, only class variables
class Dog():
age = 3 # Class variables
def __init__(self):
= "XiaoBai" # Instance variables
def run(self): # Instance methods
print("{} years old's {} is running!".format(,))
@classmethod
def eat(cls):
# print() # Class method, can't access instance variables (properties)
print("XiaoHei is {} years old".format()) # Class methods can only access class variables
@staticmethod
def sleep(name):
# Static methods have nothing to do with the class, they can only be a function of the class
# Static methods can't access class and instance variables
print("{} is sleeping".format(name))
d = Dog()
() # Invoke instance methods by instantiating objects
(d) # Calling an instance method by class name requires passing the instance object in the method
() # Invoke class methods by instantiating objects
() # Invoke class methods by class name
("XiaoLan") # Invoke static methods by instantiating objects
("XiaoLan") # Calling static methods by class name
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