Class Variable Access and Assignment

[Antoon Pardon]

Op 2005-11-04, Christopher Subich schreef <csubich.spam.block at spam.subich.block.com>:
> Antoon Pardon wrote:
>> Op 2005-11-03, Stefan Arentz schreef <stefan.arentz at gmail.com>:
>>>The model makes sense in my opinion. If you don't like it then there are
>>>plenty of other languages to choose from that have decided to implement
>>>things differently.
>> 
> >>> class foo:
> >>>   x = [5]
> >>> a = foo()
> >>> a += [6]
> >>> a.x
> [5,6]
> >>> foo.x
> [5,6]
> >>> foo.x = [7]
> >>> a.x
> [5,6]
>
> In truth, this all does make perfect sense -- if you consider class 
> variables mostly good for "setting defaults" on instances.

Except when your default is a list

class foo:
  x = [] # default

a = foo()
a.x += [3]

b = foo()
b.x

This results in [3]. So in this case using a class variable x to
provide a default empty list doesn't work out in combination
with augmented operators.

This however would work:

class foo:
  x = [] # default
    
a = foo()
a.x = a.x + [3]

b = foo()
b.x

This results in []

-- 
Antoon Pardon