Attribute definition, WHY?

[Steve Holden]

bragib at my-deja.com wrote:
> 
> Why would you want to do the following:
> 
> class A:
>    attr1 = [1,2]
>    def __init__(self,name):
>        self.name = name
> 
In this case, attr1 becomes a shared object, or class attribute,
available to all instances (and, perhaps significantly, all
instances will refer to and possibly update a single copy).

> and not
> 
> class A:
>    def __init__(self,name):
>        self.name = name
>        self.attr1 = [1,2]
> 
In this case case attr1 is an instance attribute, so each instance
of an A will have its own attr1.

> Are there benefits to the first definition?
> 
The first definition might be appropriate if you want inter-instance
communication via a shared attribute.  Such behavior has been used,
for example, to track the number of instances by incrementing a
shared counter in the __init__ method.

> Bragi
> 
> Sent via Deja.com http://www.deja.com/
> Before you buy.

Hopet his helps

regards
 Steve
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