If I understand a little bit what happen in:
def __init__(self, parameters=[]):
[...]
The list argument is built before instance creation and indeed
constructor execution.
So this is the same list instance of constructor parameter for all new
instance creation.
For me it was a bad surprise!
I never see warning about this fact in any books before.
Regards
Karim
On 01/25/2011 10:08 PM, Izz ad-Din Ruhulessin wrote:
Or the internal memory id or whatever it's called.
2011/1/25 Izz ad-Din Ruhulessin <izzaddin.ruhules...@gmail.com
<mailto:izzaddin.ruhules...@gmail.com>>
I think it has something to do with the physical id of the object
2011/1/25 Karim <karim.liat...@free.fr
<mailto:karim.liat...@free.fr>>
Hello All,
Just to share on rageous bug I encounter where 2 lists which
"should" to be different (same id) because hold by different
instances of the same class are not in fact DIFFERENT, see below:
>>> class Device():
... def __init__(self, parameters=[]):
... self.parameters = parameters
... def param(self):
... print(id(self.parameters))
...
>>> a=Device()
>>> b=Device()
>>> a.param()
140559202956568
>>> b.param()
140559202956568
When I discovered that I was puzzled because at the prompt:
>>> a = []
>>> b = []
>>> id(a)
140559202956496
>>> id(b)
140559202957000
I am not really understanding why my init in the class made it
refers to the same list object.
What is the difference with 2nd example directly at the prompt?
By the way, this one is ok:
>>> class Device():
... def __init__(self,parameters=None):
... self.parameters = None
... self.parameters = []
... def param(self):
... print(id(self.parameters))
...
>>> a=Device()
>>> b=Device()
>>> b.param()
140559202956496
>>> a.param()
140559202956568
Karim
_______________________________________________
Tutor maillist - Tutor@python.org <mailto:Tutor@python.org>
To unsubscribe or change subscription options:
http://mail.python.org/mailman/listinfo/tutor
_______________________________________________
Tutor maillist - Tutor@python.org
To unsubscribe or change subscription options:
http://mail.python.org/mailman/listinfo/tutor
