Steven D'Aprano <[EMAIL PROTECTED]> writes:
> On Sat, 15 Nov 2008 01:40:04 -0800, Rick Giuly wrote:
>
>> Hello All,
>>
>> Why is python designed so that b and c (according to code below)
>> actually share the same list object? It seems more natural to me that
>> each object would be created with a new list object in the points
>> variable.
>
> That's not natural *at all*. You're initialising the argument "points"
> with the same list every time. If you wanted it to have a different list
> each time, you should have said so. Don't blame the language for doing
> exactly what you told it to do.
Come on. The fact that this questions comes up so often (twice in 24h)
is proof that this is a surprising behaviour. I do think it is the
correct one but it is very natural to assume that when you write
def foo(bar=[]):
bar.append(6)
...
you are describing what happens when you _call_ foo, i.e.:
1. if bar is not provided, make it equal to []
2. Append 6 to bar
3. ...
--
Arnaud
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