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    Class method vs Static method in Python

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    Python’s Class Method vs. Static Method: A Comparison | Courses | Reading | Practice | Video

    This article will explain the distinction between class methods and static methods in Python, as well as when each should be used.

    python.

    As an inbuilt function decorator, @classmethod is an expression that is evaluated after your function definition is complete. The evaluation’s outcome casts a shadow on the way you define functions. Similar to how an instance method is sent the instance as its first parameter, a class method implicitly gets the class itself as its first argument in Python.

    class C(object):
    @classmethod
    def fun(cls, arg1, arg2, ...):
       ....
fun: function that needs to be converted into a class method
returns: a class method for function.
    • A class method is a method that is bound to the

      class

      and not the object of the class.
    • They have the access to the state of the class as it takes a class parameter that points to the class and not the object instance.
    • It can modify a class state that would apply across all the instances of the class. For example, it can modify a class variable that will be applicable to all the instances.

    There is no such thing as an implicitly passed-in initial parameter to a static method. Static methods are similar in that they are associated with the class itself rather than any particular instance of that class. The class state is protected from this method’s access. The class contains the function because doing so makes the most sense. Static Python Syntax:

    class C(object):
    @staticmethod
    def fun(arg1, arg2, ...):
        ...
returns: a static method for function fun.

    What makes the static method distinct from the Class method

    is:

    • A class method takes cls as the first parameter while a static method needs no specific parameters.
    • A class method can access or modify the class state while a static method can’t access or modify it.
    • In general, static methods know nothing about the class state. They are utility-type methods that take some parameters and work upon those parameters. On the other hand class methods must have class as a parameter.
    • We use @classmethod decorator in python to create a class method and we use @staticmethod decorator to create a static method in python.

    • We generally use the class method to create factory methods. Factory methods return class objects ( similar to a constructor ) for different use cases.
    • We generally use static methods to create utility functions.

    Python’s @classmethod and @staticmethod decorators are used to declare class and static methods, respectively. Let’s have a look at an illustration to see how the two concepts vary from one another. Let’s pretend we need to create a new class called “Person.” As Python doesn’t have the same method overloading features as languages like C++ and Java, factory methods must be implemented using class methods instead. In the code snippet below, we utilize a class function to infer a person’s birth year and then build a person object.

    To generate useful functions, we employ the previously described static techniques. In the code snippet below, we utilize a static method to determine whether a user is above the age of majority.

    To provide only one instance:

    class

    method:

    Python3

    Output


    class


    MyClass:



    def


    __init__(


    self


    , value):



    self


    .value


    =


    value



    def


    get_value(


    self


    ):



    return


    self


    .value

    # Create an instance of MyClass

    obj


    =


    MyClass(


    10


    )

    # Call the get_value method on the instance

    print


    (obj.get_value())


    # Output: 10
     
    10

    Statically, –

    Python3

    Output


    class


    MyClass:



    def


    __init__(


    self


    , value):



    self


    .value


    =


    value



    @staticmethod



    def


    get_max_value(x, y):



    return


    max


    (x, y)

    # Create an instance of MyClass

    obj


    =


    MyClass(


    10


    )

    print


    (MyClass.get_max_value(


    20


    ,


    30


    ))

    print


    (obj.get_max_value(


    20


    ,


    30


    ))
     
    30
30

    The full text of the Implementation

    Python3


    # Python program to demonstrate

    # use of class method and static method.

    from


    datetime


    import


    date

    class


    Person:



    def


    __init__(


    self


    , name, age):



    self


    .name


    =


    name



    self


    .age


    =


    age



    # a class method to create a Person object by birth year.



    @classmethod



    def


    fromBirthYear(


    cls


    , name, year):



    return


    cls


    (name, date.today().year


    -


    year)



    # a static method to check if a Person is adult or not.



    @staticmethod



    def


    isAdult(age):



    return


    age >


    18

    person1


    =


    Person(


    'mayank'


    ,


    21


    )

    person2


    =


    Person.fromBirthYear(


    'mayank'


    ,


    1996


    )

    print


    (person1.age)

    print


    (person2.age)

    # print the result

    print


    (Person.isAdult(


    22


    ))

    Productiveness:

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