Classes in Python

[laotseu]

Steve Holden wrote:
> "Bill Martin" <wcmartin at vnet.net> wrote ...
> 
>>I'm wondering about the value of allowing a class definition like this:
>>
>>             class C:
>>               pass
>>
>>Now I can define a = c() and b = c(), then say a.x1 = 1.2, b.x2 = 3.5 or
>>some such. If I try to print a.x2 or b.x1, I get an exception message
>>basically saying those member variables don't exist. It seems to me this
>>defeats one of the basic ideas behind OOP, that is to assign members to
>>the class definition, thus ensuring that all instantiations of a class
>>have the same member variables and methods. I know there must be a
>>reason that python allows this kind of thing that I described, but I
>>can't figure out what that reason could be. To me, it looks like a very
>>dangerous thing to do. Can someone help me understand why we'd like to
>>do it? Thanks,
>>
> 
> 
> Well, if you think it's dangerous you probably *don't* want to do it, but
> it's the easiest way to set up a data structure with named components - you
> are just taking advantage of the fact that each instance has its own
> namespace. It's a firly standard idiom, though it isn't required.
> 
> Now, other object-oriented languages can go to great pains to make sure that
> an instance's attributes can only be accessed in very controlled ways, such
> as using accessor methods (getthis(), setthat(), etc.). Python, on the other
> hand, pays you the compliment of assuming you know what you are doing, and
> "gives you enough rope to shoot yourself in the foot"!
> 
> If you choose to abuse that freedom, you end up with a limp. [Please, nobody
> ask "a limp what?"].
> 

A limp what ?

[sorry, could not resist]
Laotseu