Sorry Alan,
When I read your tutorial I was probably blind... :-D
I am going to re-read it.
Regards
Karim
On 01/26/2011 01:30 AM, Alan Gauld wrote:
"Karim" <karim.liat...@free.fr> wrote
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.
Yes that is a feature of Pythons default argument mechanism.
It has been discussed many times on this list and in the docs.
As you discovered the best way to avoid it is use None as the
default then create a new list inside the function if it is None.
I never see warning about this fact in any books before.
Its quite commonly warned against but until you get bitten
the significance just passes you by! I bet if you look out for
it now you'll see it often ebnough!
HTH,
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