optional argument to a subclass of a class

[Chris Rebert]

On Fri, May 21, 2010 at 11:38 AM, Alex Hall <mehgcap at gmail.com> wrote:
> On 5/21/10, Christian Heimes <lists at cheimes.de> wrote:
>> Am 21.05.2010 04:56, schrieb Alex Hall:
>>> Hi all,
>>> I am now trying to allow my classes, all of which subclass a single
>>> class (if that is the term), to provide optional arguments. Here is
>>> some of my code:
>>>
>>> class Craft():
>>>   def __init__(self,
>>>   name,
>>>   isAircraft=False,
>>>   id=helpers.id(),
>>>   hits=0,
>>>   weapons=[]):
>>
>> I hope you are aware that helpers.id() is called just once when the
>> *class* is defined and that the list weapons is shared across all
>> instances of the craft class. :)
> I know id is called once, but what do you mean weapons is shared?

Read the "Important warning" on
http://docs.python.org/tutorial/controlflow.html#default-argument-values
`weapons` will be the *exact same list object* for all Craft instances
the way you have it currently (i.e. it will not be copied and changes
to it will affect all Crafts).

Cheers,
Chris
--
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