What is the significance of a function without a 'self' argument insde a class?

Question

class a:
    def b():
        ...

what is the Significance of b

thanks

---

class a:
    @staticmethod    
    def b():
        return 1
    def c(self):
        b()

print a.b()
print a().b()
print a().c()#error

and

class a:
    @staticmethod    
    def b():
        return 1
    def c(self):
        return self.b()

print a.b()
print a().b()
print a().c()
#1
#1
#1

Answer 1

Syntax error. Try calling it.

>>> class a:
...     def b():
...             return 1
... 
>>> x=a()
>>> x.b()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: b() takes no arguments (1 given)

See also:

>>> class a:
...     def b():
...             return 1
...     def c(self):
...             return b()
... 
>>> a().c()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 5, in c
NameError: global name 'b' is not defined

Answer 2

Basically you should use b() as staticmethod so that you can call it either from Class or Object of class e.g:

bash-3.2$ python
Python 2.6 (trunk:66714:66715M, Oct  1 2008, 18:36:04) 
[GCC 4.0.1 (Apple Computer, Inc. build 5370)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> class a:
...    @staticmethod
...    def b():
...       return 1
... 
>>> a_obj = a()
>>> print a.b()
1
>>> print a_obj.b()
1
>>>

Answer 3

in a class method self is the instance of the class the method is called on. beware that self is not a keyword in python just a conventional name given to the first argument of a method.

look at this example:

class A:

    def foo(self):
        print "I'm a.foo"

    @staticmethod
    def bar(s):
        print s

a = A()
a.foo()
A.foo(a)

here a is the instance of the class A. calling a.foo() you are invoking the method foo of the instance a while A.foo(a) invoke the method foo in the class A but passing the instance a as first argument and they are exactly the same thing (but never use the second form).

staticmethod is a decorator that let you define a class method as static. that function is no more a method and the first argument is not the instance of the class but is exactly the first argument you passed at that function:

a.bar("i'm a static method")
i'm a static method
A.bar("i'm a static method too")
i'm a static method too

PS. i don't want to bothering you but these are the very basis of python, the python tutorial is a nice start for the beginners.