functions, list, default parameters

[Lawrence D'Oliveiro]

In message <mailman.608.1288889032.2218.python-list at python.org>, Robert Kern 
wrote:

> On 11/4/10 2:07 AM, Lawrence D'Oliveiro wrote:
>
>> In message<mailman.504.1288718704.2218.python-list at python.org>, Robert
>> Kern wrote:
>>
>>> On 11/2/10 2:12 AM, Lawrence D'Oliveiro wrote:
>>>
>>>> In message<mailman.475.1288670833.2218.python-list at python.org>, Robert
>>>> Kern wrote:
>>>>
>>>>> "Immutable objects" are just those without an obvious API for
>>>>> modifying them.
>>>>
>>>> They are ones with NO legal language constructs for modifying them.
>>>> Hint: if a selector of some part of such an object were to occur on the
>>>> LHS of an assignment, and that would raise an error, then the object is
>>>> immutable. The interpreter already knows all this.
>>>
>>> Incorrect. RHS method calls can often modify objects.
>>
>> So bloody what?
> 
> So examining LHS "selectors" is not sufficient for determining
> immutability.

Yes it is. All your attempts at counterexamples showed is that it is not 
necessary, not that it is not sufficient.