Hello, and thanks for your contribution!

I'm a bot set up to make sure that the project can legally accept this contribution by verifying everyone involved has signed the PSF contributor agreement (CLA).

Recognized GitHub username

We couldn't find a bugs.python.org (b.p.o) account corresponding to the following GitHub usernames:

@Van-Quyet-DO

This might be simply due to a missing "GitHub Name" entry in one's b.p.o account settings. This is necessary for legal reasons before we can look at this contribution. Please follow the steps outlined in the CPython devguide to rectify this issue.

You can check yourself to see if the CLA has been received.

Thanks again for the contribution, we look forward to reviewing it!

I think the docs should remain as is. Consider:

# Shallow Copy: just copy over the two pointers
>>> x = [["a"], ["b"]]
>>> y = x.copy()
>>> x[0] is y[0]
True
>>> x[0].append("c")
>>> x
[['a', 'c'], ['b']]
>>> y
[['a', 'c'], ['b']]

# Deep Copy: recursively copy over the contents of the two lists
>>> from copy import deepcopy
>>> x = [["a"], ["b"]]
>>> y = deepcopy(x)
>>> x[0] is y[0]
False
>>> x[0].append("c")
>>> x
[['a', 'c'], ['b']]
>>> y
[['a'], ['b']]

While it's correct that list.copy() makes a copy (not just an alias like y = x), it is not a deep copy, since the contents are just aliased.

Could you create a bpo issue and associate this PR to the bpo issue. Thank you.

I may be wrong but to me x = y is not synonymous to object contents copy but reference copy only.

list.copy indeed returns a different object, that is, a new list but the copy is not deep. You have a new list but each position points to the same object. The fact that the lists are different doesn't mean they were deeply copied.

Deep copy is when you recursively copy all contents of an object, not just the references.

You can use python-tutor to visualize that:

As discussed, the proposed change is incorrect.