Simon Bunker wrote:
> Hi I have code similar to this:
>
> class Input(object):
>
> def __init__(self, val):
> self.value = val
>
> def __get__(self, obj, objtype):
> return self.value
>
> def __set__(self, obj, val):
> # do some checking... only accept floats etc
> self.value = val
>
> class Node(object):
>
> a = Input(1)
> b = Input(2)
>
> I realise that a and b are now class attributes - however I want to do this:
>
> node1 = Node()
> node2 = Node()
>
> node1.a = 3
> node2.b = 4
>
> And have them keep these values per instance. However now node1.a is 4
> when it should be 3.
[snip]
> Is there any way of doing this nicely in Python?
The easiest way is to store the value in a hidden attribute of the
object. For instance:
class Input(object):
def __init__(self,default,name):
self.default = default
self.name = name # or, create a name automatically
def __get__(self,obj,objtype):
return getattr(obj,self.name,self.default)
def __set__(self,obj,value):
setattr(obj,self.name,value)
class Node(object):
a = Input(1,"_a")
b = Input(2,"_b")
Carl Banks
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