ENH: confusing name for 'copy' argument in to_numpy() method

[Abdelgha-4]

I found the following behavior a bit unexpected from the name of the argument.

The default (copy=False) may return a copy instead of a view. copy=True always returns a copy, but copy=False does not always return a view.

I think changing the argument name to something like always_copy would be more clear about what it is doing.

[attack68]

-1, whilst what you are proposing might be clearer, I consider the existing docs explicitly clear enough. Perhaps expanding:

copy=False does not always return a view and still may return a copy depending upon object type.

[mzeitlin11]

Agreed with @attack68, this conditional copying mirrors numpy behavior as well, for example in https://numpy.org/doc/stable/reference/generated/numpy.array.html

If true (default), then the object is copied. Otherwise, a copy will only be made if array returns a copy, if obj is a nested sequence, or if a copy is needed to satisfy any of the other requirements (dtype, order, etc.).

[jorisvandenbossche]

Small note that in numpy they have been discussing changing the arguments for this keyword, cfr numpy/numpy#19173 (and mailing list discussions), to be able to distinguish those cases of "never coying" vs "only copy when needed"

[simonjayhawkins]

for EAs the backing data may not necessarily be a NumPy array, so it is not always possible to return a view from to_numpy.

So we can't necessarily make the behavior of copy align with NumPy semantics. That said, +1 on leaving as is for now and await the outcome of the Numpy discussion.

[Abdelgha-4]

NumPy discussion about this has been ended in numpy/numpy#19173, so I guess we could make a decision about this issue now ?