python how to invoke classmethod if I have only it's object

Question

Assuming I have class

class Class(object):
   @register_method_to_later_execution      
   @classmethod
   def my_class_method(cls):
   ...

and @classmethod object. like this a = Class.my_class_method I need to be able to start executing it only if I having an a object. Is it possible to do that? and if possible - how It could be done?

The problem that I creating reference a at the moment of class creating (in decorator @register_method_to_later_execution for my_class_method) during the import

At that moment I just only have an object, and if I later trying to execute it, it throws class method is not callable

Possible duplicate of (deleted) [question](http://stackoverflow.com/questions/25364839/python-how-to-invoke-classmethod-object) — Ffisegydd, Aug 18 '14 at 14:27
Please show what you mean by "creating reference a at the moment of class creating". — chepner, Aug 18 '14 at 14:39
Add method to the dictionary, map it with name `method_a` for example, and further based on that mapping I could get object `a` and when I will have object, I should be able to execute it somehow — Ph0en1x, Aug 18 '14 at 14:46

ptr · Answer 1 · 2014-08-18T14:52:24.870

Kinda trivial to test this yourself.

>>> class MyClass(object):
...     @classmethod
...     def my_class_method(cls):
...         print "hello world"
... 
>>> a = MyClass.my_class_method
>>> a
<bound method type.my_class_method of <class '__main__.MyClass'>>
>>> a()
hello world

Edit: If I understand you correctly from your edit (and I'm not at all sure that I do), it looks like you're trying to reference a class method before the class has actually been defined? That is not possible.

Use the @staticmethod decorator instead as that does not pass in the class variable as an argument.

Edit2: If you need the method to be a class method because you need access to the class variable for some reason, then you're out of luck and I would suggest rethinking your approach, as this one seems very strange to me and almost certainly isn't a good one :)

del-boy · Answer 2 · 2014-08-18T17:33:20.880

0

Just call it as you normaly would. Example:

In [1]: class Foo(object):
   ...:     @classmethod
   ...:     def my_method(cls):
   ...:         print('in my method')
   ...:

In [2]: foo = Foo()

In [3]: foo.my_method()
in my method

In [4]: Foo.my_method()
in my method

In [5]: method_reference = Foo.my_method

In [6]: method_reference()
in my method

In [7]:

edited Aug 18 '14 at 17:33

answered Aug 18 '14 at 14:27

del-boy

3,556
3
26
39

This isn't quite the same situation - the OP has a name referencing the class method itself, not an instance of the class – jonrsharpe Aug 18 '14 at 14:31
You are right, I missed that. I have edited example and added example that OP is looking for. – del-boy Aug 18 '14 at 17:34

python how to invoke classmethod if I have only it's object

2 Answers2

Linked