[Tutor] beginner: using optional agument in __init__ breaks my code

[Pawel Kraszewski]

Dnia niedziela, 25 czerwca 2006 22:45, Bob Gailer napisał:

> To get the behavior I think you want try:
>
>     def __init__(self, q = None):
>         if not q: q = []
>         self.queue = q

I would disagree... This sure works for empty arguments, but:

>>> u = [1,2,3]
>>> a = Queue(u)
>>> b = Queue(u)
>>> a.insert(12)
>>> print b

gives [1, 2, 3, 12] which is still wrong. However assigning self.queue a COPY 
of parameter (empty or not) gives the desired result:

    def __init__(self, q = []):
        self.queue = q[:]


-- 
 Pawel Kraszewski