[Tutor] why "self" in methods?

[orbitz at ezabel.com]

Taking no self argument is not the same as unbound. unbound just means the
method is not bound to an instance.  Take Danny's example of calling super
class's method.
>From Nevow's code:
class Renderer(ChildPrefixMixin, resource.Resource, RenderFactory, DataFactory):
    def __init__(self, original=None):
	# Some other junk here...
        resource.Resource.__init__(self)

Using unbound method to call the constructor of one of the parent classes.


On Mon, 5 Apr 2004 11:25:17 +0100
"Alan Gauld" <alan.gauld at blueyonder.co.uk> wrote:

> > Yes: if one needs to call methods of a superclass, one way to do it
> is
> > with an explicit call to the "unbound" method of the superclass.
> Here's a
> > completely useless toy example:
> >
> > ###
> > >>> class SomeClass(object):
> > ...     def sayHello(self):
> > ...         print "hi, I'm SomeClass"
> > ...
> 
> But sayHello is not unbound in the sense mentioned in the OP
> (which actually may not be the right term!). What I was really
> asking was what use (if any) do methods without a self parameter have?
> 
> Python allows you to create them but, so far as I can tell,
> you can never use them?
> 
> ie:
> 
> >>> class SomeClass(object):
> ...     def sayHello(self):
> ...         print "hi, I'm SomeClass"
> ...     def noSelf():
> ...         print "I'm selfless"
> ...
> >>> print SomeClass.sayHello
> <unbound method SomeClass.sayHello>
> >>> print SomeClass.noSelf
> <unbound method SomeClass.noSelf>
> 
> So far they look the same.
> 
> >>> s = SomeClass()
> >>> print s.sayHello
> <bound method SomeClass.sayHello of <__main__.SomeClass object at
> 0xa06672c>>
> >>> print s.unboundMeth
> <bound method SomeClass.unboundMeth of <__main__.SomeClass object at
> 0xa06672c>>
> 
> And they still look similar after binding
> 
> >>> s.sayHello()
> hi, I'm SomeClass
> >>> s.noSelf()
> Traceback (most recent call last):
>   File "<stdin>", line 1, in ?
> TypeError: noSelf() takes no arguments (1 given)
> 
> But when you try to call them....
> 
> Now it might be sensible to tread noSelf as a class method
> - ie one which operates on the class level rather than the
> instance level...
> 
> >>> SomeClass.noSelf()
> Traceback (most recent call last):
>   File "<stdin>", line 1, in ?
> AttributeError: type object 'SomeClass' has no attribute 'noSelf'
> >>>
> 
> But nope, you can't do that either.
> 
> So is there any way to use these? And if not why does Python happily
> allow them? It should be possible to detect parameterless function
> definintions within a class scope surely? (The only reason I can
> think of might be to allow definition of higher order methods
> - ie methods which return functions which may not take
> parameters.... but even that should be detectable...)
> 
> Just curious,
> 
> Alan G.
> 
> 
> 
> 
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