matthewperpick wrote:
> Check out this toy example that demonstrates some "strange" behaviour
> with keyword arguments and inheritance.
>
> =================================
>
> class Parent:
> def __init__(self, ary = []):
> self.ary = ary
>
[snip]
As pointed out earlier, default values for arguments are evaluated
when the function is defined, not when it is called. This creates
confusion if this value is mutable and later mutated; I got confused
by it when I started python. So it is often not a good idea to use
mutable objects as default arguments.
A simple fix:
def __init__(self, ary=None):
if ary is None: ary = []
self.ary = ary
--
Arnaud
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