Inheritance question

[Robert Bossy]

Hi,

I'm not sure what you're trying to actually achieve, but it seems that 
you want an identificator for classes, not for instances. In this case, 
setting the id should be kept out of __init__ since it is an instance 
initializer: make id static and thus getid() a classmethod.
Furthermore, if you have several Foo subclasses and subsubclasses, etc. 
and still want to use the same identificator scheme, the getid() method 
would better be defined once for ever in Foo. I propose you the following:

<code>
class Foo(object):
    id = 1

    def getid(cls):
        if cls == Foo: return str(cls.id)
        return '%s.%d' % (cls.__bases__[0].getid(), cls.id) # get the 
parent id and append its own id
    getid = classmethod(getid)

class FooSon(Foo):
    id = 2

class Bar(Foo):
    id = 3

class Toto(Bar):
    id = 1

# Show me that this works
for cls in [Foo, FooSon, Bar, Toto]:
    inst = cls()
    print '%s id: %s\n    also can getid from an instance: %s\n' % 
(cls.__name__, cls.getid(), inst.getid())
</code>

One advantage of this approach is that you don't have to redefine the 
getid() method for each Foo child and descendent. Unfortunately, the 
"cls.__bases__[0]" part makes getid() to work if and only if the first 
base class is Foo or a subclass of Foo. You're not using multiple 
inheritance, are you?

RB