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Classmethods and Staticmethods

Three method shapes: instance, class, and static each receives a different first argument.

An instance method receives the instance as self and reads its state. This is the default and the right shape when the work depends on a particular object's data.

Source

class Date:
    def __init__(self, year, month, day):
        self.year = year
        self.month = month
        self.day = day

    def display(self):
        return f"{self.year}-{self.month:02d}-{self.day:02d}"

today = Date(2026, 5, 9)
print(today.display())

Output

2026-05-09

@classmethod makes the method receive the class itself as cls. The canonical use is an alternate constructor that parses some other input format and calls cls(...). Because cls is the actual class, subclasses calling the same method get an instance of their own type.

Source

class Date:
    def __init__(self, year, month, day):
        self.year = year
        self.month = month
        self.day = day

    @classmethod
    def from_string(cls, text):
        year, month, day = (int(part) for part in text.split("-"))
        return cls(year, month, day)

later = Date.from_string("2026-12-31")
print(later.year, later.month, later.day)

Output

2026 12 31

@staticmethod strips the implicit first argument. The function lives on the class for namespacing like Date.is_leap_year(2024) but does not touch any instance or class state.

Source

class Date:
    @staticmethod
    def is_leap_year(year):
        return year % 4 == 0 and (year % 100 != 0 or year % 400 == 0)

print(Date.is_leap_year(2024))
print(Date.is_leap_year(2025))

Output

True
False

Side by side: instance methods receive the instance, classmethods receive the class, staticmethods receive nothing. Classmethods and staticmethods can be called on either the class or an instance.

Source

class Demo:
    def instance_method(self):
        return type(self).__name__

    @classmethod
    def class_method(cls):
        return cls.__name__

    @staticmethod
    def static_method():
        return "no receiver"

print(Demo().instance_method())
print(Demo.class_method())
print(Demo.static_method())

Output

Demo
Demo
no receiver

Notes

Instance methods need an instance; classmethods and staticmethods can be called on the class.

Use @classmethod for alternate constructors and class-level operations that respect subclassing.

Use @staticmethod only when a function is truly independent of instance and class state but still belongs in the class's namespace.

A free function is often the right answer when neither decorator applies.

Classmethods and Staticmethods

See also

Run the complete example

Expected output