class unbound method and datetime.datetime.today()

[cinsky]

Hi, I got confused when I learned the function datetime.today().

So far I learned, unless an instance is created, it is not possible to
call the class method. For example:

class Foo:
def foo(self):
pass

Foo.foo() # error: unbound method foo().

What makes me confused is that datetime class? in datetime module
provides today() function that returns the datetime object.

>>import datetime
datetime.datetime.today()

datetime.datetime(2007, 1, 9, 15, 34, 35, 23537)

It looks like that datetime class provides today() method that can be
callable even if it is unbound method. Do I correct?

If it is possible to make that kind of function (looks like static
member function in C++), how can I make that?

Thanks in advance.

[Diez B. Roggisch]

ci****@gmail.com schrieb:

Hi, I got confused when I learned the function datetime.today().

So far I learned, unless an instance is created, it is not possible to
call the class method. For example:

class Foo:
def foo(self):
pass

Foo.foo() # error: unbound method foo().

What makes me confused is that datetime class? in datetime module
provides today() function that returns the datetime object.

>>>import datetime
datetime.datetime.today()

datetime.datetime(2007, 1, 9, 15, 34, 35, 23537)

It looks like that datetime class provides today() method that can be
callable even if it is unbound method. Do I correct?

If it is possible to make that kind of function (looks like static
member function in C++), how can I make that?

It is called a classmethod (in contrast to an instancemethod, which is
the usual thing), and you can do it - depending on the version of python
you have - using the built-in funtion/decorator "classmethod". Like this:

class Foo(object):

@classmethod
def bar(cls):
pass
Note that a classmethod gets passed the class as first argument, not an
instance.

You can also create static methods, using "staticmethod". They won't get
passed anything.

Diez