Op 11/01/2023 om 16:33 schreef Jen Kris via Python-list:
Yes, I did understand that. In your example, "a" and "b" are the same pointer,
so an operation on one is an operation on the other (because they’re the same memory block).
Sorry if you feel I'm being overly pedantic, but your explanation "an
operation on one is an operation on the other (because they’re the same
memory block)" still feels a bit misguided. "One" and "other" still make
it sound like there are two objects, and "an operation on one" and "an
operation on the other" make it sound like there are two operations.
Sometimes it doesn't matter if we're a bit sloppy for sake of simplicity
or convenience, sometimes we really need to be precise. I think this is
a case where we need to be precise.
So, to be precise: there is only one object, with possible multiple
names to it. We can change the object, using one of the names. That is
one and only one operation on one and only one object. Since the
different names refer to the same object, that change will of course be
visible through all of them.
Note that 'name' in that sentence doesn't just refer to variables (mx1,
arr1, ...) but also things like indexed lists (mx1[0], mx1[[0][0], ...),
loop variables, function arguments.
The correct mental model is important here, and I do think you're on
track or very close to it, but the way you phrase things does give me
that nagging feeling that you still might be just a bit off.
--
"Peace cannot be kept by force. It can only be achieved through understanding."
-- Albert Einstein
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