Clarification on Immutability please
Am 21.01.2020 19:38 schrieb Chris Angelico:
> On Wed, Jan 22, 2020 at 4:42 AM Stephen Tucker <stephen_tucker at sil.org>
>> and even that the first id(mytup) returns the same address as the
>> one, I am left wondering exactly what immutability is.
Let's look at id()'s documentation:
Return the ?identity? of an object. This is an integer which is
guaranteed to be unique and constant for this object during its
lifetime. Two objects with non-overlapping lifetimes may have the same
> Are you sure that it does? I can't reproduce this. When you slice the
> first two from a tuple, you create a new tuple, and until the
> assignment happens, both the new one and the original coexist, which
> means they MUST have unique IDs.
I'd expect that, too, but an "atomic" reassignment would not contradict
>> Somehow, it seems, tuples can be reduced in length (from the far end)
>> (which is not what I was expecting), but they cannot be extended
>> (which I
>> can understand).
Different ID means different object, but identical ID doesn't mean
identical object. The Python implementation allows re-use of an object's
ID after the object has been destroyed, and the documentation mentions