I am curious about why we need the @staticmethod
decorator to declare method as static
. I was reading about static methods in Python, and I came to know that static method can be callable without instantiating its class. So I tried the two examples below, but both do the same:
class StatMethod: def stat(): print("without Decorator") class StatMethod_with_decorator: @staticmethod def stat(): print("With Decorator")
If I call the stat()
method on the class directly, both print/show the values below:
>> StatMethod.stat() without Decorator >> StatMethod_with_decorator.stat() With Decorator
Having a static method avoids that. There are very few situations where static-methods are necessary in Python. The @staticmethod form is a function decorator. Also see classmethod() for a variant that is useful for creating alternate class constructors.
We use @classmethod decorator in python to create a class method and we use @staticmethod decorator to create a static method in python.
The @staticmethod is a built-in decorator that defines a static method in the class in Python.
This decorator exists so you can create class methods that are passed the actual class object within the function call, much like self is passed to any other ordinary instance method in a class. This follows the static factory pattern very well, encapsulating the parsing logic inside of the method itself.
You need the decorator if you intend to try to call the @staticmethod
from the instance of the class instead of of the class directly
class Foo(): def bar(x): return x + 5 >>> f = Foo() >>> f.bar(4) Traceback (most recent call last): File "<pyshell#7>", line 1, in <module> f.bar(4) TypeError: bar() takes 1 positional argument but 2 were given
Now if I declare @staticmethod
the self
argument isn't passed implicitly as the first argument
class Foo(): @staticmethod def bar(x): return x + 5 >>> f = Foo() >>> f.bar(4) 9
The documentation describes some transformations that are done when calling a user defined method:
Note that the transformation from function object to (unbound or bound) method object happens each time the attribute is retrieved from the class or instance. In some cases, a fruitful optimization is to assign the attribute to a local variable and call that local variable. Also notice that this transformation only happens for user-defined functions; other callable objects (and all non-callable objects) are retrieved without transformation. It is also important to note that user-defined functions which are attributes of a class instance are not converted to bound methods; this only happens when the function is an attribute of the class.
For methods marked as staticmethod this is different:
Static method objects provide a way of defeating the transformation of function objects to method objects described above. A static method object is a wrapper around any other object, usually a user-defined method object. When a static method object is retrieved from a class or a class instance, the object actually returned is the wrapped object, which is not subject to any further transformation. Static method objects are not themselves callable, although the objects they wrap usually are. Static method objects are created by the built-in staticmethod() constructor.
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