[EMAIL PROTECTED] wrote:
> Hello,
>
> I have a class called 'Axis' that I use as a base class for several
> types of axes that can be created by a grid generation program that I
> have written: equally-spaced grids, logarithmic grids, etc. In any
> case, if I use this base class by itself, I see some puzzling
> behaviour:
> #############
> class Axis:
> ends = []
> N = None
> def __init__(self):
> pass
>
> x = Axis()
> y = Axis()
> z = Axis()
>
> x.ends.append((0,2))
>
> print x.ends,y.ends,z.ends
> #############
> Running the following code outputs:
>>>> [(0, 2)] [(0, 2)] [(0, 2)]
>
> Can anyone explain this?
Well, you are using a class variable - Axis.ends. It's shared among all
instances of Axis class. To have it separate setup it in __init__ like:
class Axix:
def __init__(self):
self.ends = []
self.N = None
You see, code inside class, but outside methods is executed only once and
any variables are then linked with class, and not instances (more/less).
Take look at: http://docs.python.org/tut/node11.html
~TomekP
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