[Python-Dev] Bug report: empty dictionary as default class argument

[Fredrik Lundh]

Idan Sofer wrote:
>
> I have found a rather annoying bug in Python, present in both Python 1.5
> and Python 2.0.
>
> If a class has an argument with a default of an empty dictionary, then
> all instances of the same class will point to the same dictionary,
> unless the dictionary is explictly defined by the constructor.

maybe you should check the documentation (or the FAQ) before
submitting bugs?

    http://www.python.org/doc/current/ref/function.html

    Default parameter values are evaluated when the function
    definition is executed. This means that the expression is evaluated
    once, when the function is defined, and that that same ``pre-
    computed'' value is used for each call. This is especially important
    to understand when a default parameter is a mutable object,
    such as a list or a dictionary: if the function modifies the object
    (e.g. by appending an item to a list), the default value is in
    effect modified.

Cheers /F

PS. when you do report real bugs, please use the bug tracker:

    http://sourceforge.net/tracker/?group_id=5470&atid=105470

"is this a bug" questions should be sent to comp.lang.python