Thus spake keithlackey (keithlackey at deegroup.com):
> class structure:
> def __init__(self, folders = []):
^^^^^^^^^^^^^
Here's your problem. To understand what's going on, you need to know two
things:
- Default arguments are only evaluated ONCE when the
Python interpreter executes the class definition.
- A list is a mutable object.
So, what's happening is that both your class instances are
getting the _same_ list as a default instantiation argument.
You are modifying the list through the first class instance,
and then seeing the same change when you view the list via the
second class instance.
As a rule of thumb, simply never use a mutable object as a
default argument to a function or method unless you really
know what you're doing, and actually want the behaviour
you're going to get. In your case, you probably want
something like:
def __init__(self, folders = None):
if folders is None:
self.folders = []
Cheers,
Aldo
--
Aldo Cortesi
aldo at nullcube.com
http://www.nullcube.com
Off: (02) 9283 1131
Mob: 0419 492 863
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