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In the previous article, we have introduced you to the concept of a static variable in Python and its features. In this article, we are going to explain the feature of a static method in Python i.e. how to define a static method in a class, how to call a static method and its use.

Features of a static method

• A static method is bound to a class in which it is defined and not to the objects of the class.


• While each object of a class gets its own copy of a general method of a class, only one copy of a static method is shared by all the objects of a class.


• A static method should be accessed by its class name with a dot operator, though in some cases it can even be accessed by an object of its class.


• Because a static method is not bound to an object of a class, so unlike the definition of a general method of a class, we do not have to specify self keyword in the parameters of a static method.

• Creating a static method using @staticmethod decorator


We could create a static method of a class by using the @staticmethod decorator. This decorator is placed just before the definition of a static method in a class.



# Python - Defining a static method


class Test:
 
 
    # Defining a static method using @staticmethod decorator

    @staticmethod
    def stat():
        print('Hello from the static method')


In the example above, we have defined a static method named stat() which belongs to the class Test, by using the @staticmethod decorator just before the static method's definition.

Note: As you can see in the program above, unlike the definition of a general method of a class in Python, we have not specified the self keyword in the parameters of a static method, because self refers to the currently executing object, while a static method is a class method and has got nothing to do with its objects. Now, let us see the ways to call a static method.






• Calling a static method using its class name.


A static method can be accessed directly by using its class name and a dot operator. Let us see an example.



# Python - A static method


class Test:
 
 
    # Defining a static method using @staticmethod decorator

    @staticmethod
    def stat():
        print('Hello from the static method')



# Calling the static method using its class name
Test.stat()





Output is :




Hello from the static method


We have called the static method stat() by using its class name i.e. Test with a dot operator.




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• Accessing a static method using the object of its class.


A static method can also be accessed by using the object of its class with a dot operator, but, with a condition that after defining the static method, we must not define a general method with the same name as the static method, which could overshadow/replace the definition of the static method.

Note : When a static method is called by an object of its class, it knows nothing about the instance it was called on because it belongs to the class and has got nothing to do with its objects. In this case, the object name is internally replaced by the class name while calling a static method. Let us see an example.



# Python - A static method


class Test:
 
 
    # Defining a static method using @staticmethod decorator

    @staticmethod
    def stat():
        print('Hello from the static method')



#Creating an object of class Test
ob = Test()


# Calling the static method using the object of its class
ob.stat()





Output is :




Hello from a static method








• Accessing a static method from within its class method.


A static method can be accessed from within a general method of its class in two ways :
• By using its class name.
• By using the self keyword, which refers to the current object of its class. Let us see an example. Let us see an example.




# Python - A static method


class Test:
 
    # Defining a static method using @staticmethod decorator

    @staticmethod
    def stat():
        print('Hello from the static method')



    # Defining a general method
    def method(self):
    
        #Calling the static method from within this general method using self keyword i.e. current object.
        #In this case, an object name is internally replaced by its class name while calling a static method
        self.stat()

        
        #Calling the static method from within this general method using the class name
        Test.stat()


# Creating an object of class Test
ob = Test()

# Calling the method()
ob.method()





Output is :




Hello from a static method
Hello from a static method








• Instance method overshadowing static method.


After defining a static method, defining an instance method with the same as a static method will always overshadow/replace the definition of the static method.

In such a case, accessing a static method by using the object of its class(like in the previous example) will give us access to the instance method and not the static method.



# Python - A general method overshadowing a static method


class Test:
 
    # Defining a static method using @staticmethod decorator

    @staticmethod
    def stat():
        print('Hello from a  static method')



    # Defining a general method with the same name as a static method
    # Hence, the definition of static method will be overshadowed i.e. replaced by this general method
    def stat(self):
          print('Hello from a general method')



# Creating an object of class Test
ob = Test()


# This will call the general method and not the static method
# because the general method definition has overshadowed i.e. replaced the static method definition
ob.stat()


# Calling the static method using its class name will only lead to an error because it doesn't exist anymore
Test.stat()





Output is :




Hello from a general method
Traceback (most recent call last):
  File "D:/Python Programs/static15.py", line 27, in <module>
    Test.stat()
TypeError: stat() missing 1 required positional argument: 'self'





Program Analysis



In the example above, the definition of a static method named stat() has been replaced by the definition of a general method with the same name, therefore -
• Accessing the static method named stat() with the object of its class has only given us access to the instance method of the class.
• Accessing a static method named stat() by using its class name has lead to an error because its definition has been overshadowed/replaced by the definition of a general method with the same name stat().







• Accessing static variable within a static method


A class method is defined with the cls keyword to access the class and its properties, whereas, a general method is defined with the self keyword to access the current object and unlike these methods, the static method has got nothing of its own to access either the properties of a class or its instances, but we could still access the static variables of a class from within a static method by using its class name. Let us see how.



# Python - Modifying class/static variable from within a static method 


class Test:

    # A class/static variable
    i=1



    @staticmethod
    def stat():
        Test.i = Test.i+10 # A class variable is modified by accessing it with its class name
    
        

# Accessing the class/static  variable using its class name
print('i = ',Test.i)


#Calling the static method using its class name
Test.stat()


# Accessing the class/static  variable using its class name
print('i = ', Test.i)





Output is :




i = 1
i = 11


As you see in the last program, we have accessed and modified a class/static variable named, i, from within a static method by using its class name, Test.






• Incorrect access of a static method.


A static method cannot be accessed directly.



# Python - A static method


class Test:
 
    # Defining a static method using @staticmethod decorator

    @staticmethod
    def stat():
        print('Hello from the static method')


# Incorrect direct access of a static method
stat()





Output is :




Traceback (most recent call last):
  File "D:/Python Programs/static13.py", line 15, in <module>
    stat()
NameError: name 'stat' is not defined


As you see in the last program, direct access of a static method leads to an error, therefore, a static method should only be accessed by using its class name.






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