Imitating a static method

Question

Is this the correct way to imitate a static method in Python? Does Python allow static methods?

class C(object):

    def show(self,message):
        print("The message is: {}".format(message))

m = "Hello World!"
C.show(C,message=m)

The message is: Hello World!

score 3 · Answer 1 · answered Aug 13 '13 at 14:46

The idiomatic translation of a static method from other languages is usually a module-level method.

def show(message):
    print("The message is: {}".format(message))

The answers telling you that python has @staticmethods are correct, and also misleading: it is usually correct to just use a module-level function.

arshajii · Accepted Answer · 2013-08-13T15:03:28.243

2

You should use @classmethod:

@classmethod
def show(cls, message):
        print("The message is: {}".format(message))

The difference between a classmethod and a staticmethod is that the latter knows nothing about its enclosing class, whereas the former does (via the cls argument). A staticmethod can just as easily be declared outside the class.

If you don't want show() to know anything about C, either use @staticmethod or declare show() outside of C.

edited Aug 13 '13 at 15:03

answered Aug 13 '13 at 14:15

arshajii

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On classmethods, better use `cls` instead of `self`. – glglgl Aug 13 '13 at 14:16
This is incorrect. See @glglgl answer. – johnharris85 Aug 13 '13 at 14:17
1

@JHarris Ist is another valid way to do so; it will work as well. Mine is cleaner, however. – glglgl Aug 13 '13 at 14:18
1

It works sure, but it's not right ;) – johnharris85 Aug 13 '13 at 14:19
@JHarris I don't agree. – arshajii Aug 13 '13 at 14:21

score 2 · Answer 3 · answered Aug 13 '13 at 14:16

2

You should use @staticmethod:

@staticmethod
def show(message):
    print("The message is: {}".format(message))

answered Aug 13 '13 at 14:16

glglgl

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Sorry, @arshajii, could not resist to imitate your answer 1:1 :-) – glglgl Aug 13 '13 at 14:17
1

It all depends if they're after a C++ style static method aka, a Python class method, or a Python static method, which is rarely of any use – Jon Clements Aug 13 '13 at 14:18
1

I guess @JonClements is right, we're missing some context. Static methods are good for grouping functionality which doesn't operate on an instance. See Raymond Hettinger's class tools talk from PyCon for some extra stuff on that. – johnharris85 Aug 13 '13 at 14:21
1

Downvote? Why? It is definitely not complete wrong, as far as we can tell by now. – glglgl Aug 13 '13 at 14:28
@GLES And if someone downvotes your question, you downvote all your answers? Wow. – glglgl Aug 13 '13 at 14:34
Who said so? I upvoted all the answers including comments. – Patt Mehta Aug 13 '13 at 14:35
@GLES Your comment sounded like it. If I was wrong, I am sorry. – glglgl Aug 13 '13 at 14:35
No worries :) The proof - http://postimg.org/image/6fa5gocf3/ – Patt Mehta Aug 13 '13 at 14:37

score 1 · Answer 4 · answered Aug 13 '13 at 14:42

You can use the decorator @classmethod. That won't pose a problem. Additionally

if a class method is called for a derived class, the derived class object is passed as the implied first argument (http://docs.python.org/3.3/library/functions.html#classmethod).

class C1(object):

    @classmethod
    def show(cls,message):
        print("[{}] The message is: {}".format(cls,message))

class C2(C1):
    pass

m = "Hello World!"
C2.show(message=m)
# vs. C1.show(message=m) with output [<class '__main__.C1'>] The message is: Hello World!

[<class '__main__.C2'>] The message is: Hello World!

Imitating a static method

4 Answers4