`bytearray.maketrans()` returns a `bytes` type value instead of a `bytearray` type value

[hyperkai]

Bug report

Bug description:

bytearray.maketrans() returns a bytes type value instead of a bytearray type value as shown below:

table = bytearray.maketrans(b'abc', b'xyz')
table = bytearray.maketrans(bytearray(b'abc'), bytearray(b'xyz'))

print(type(table)) # <class 'bytes'>

So, bytearray.maketrans() should return a bytearray type value like below:

table = bytearray.maketrans(b'abc', b'xyz')
table = bytearray.maketrans(bytearray(b'abc'), bytearray(b'xyz'))

print(type(table)) # <class 'bytearray'>

In addition, bytes.maketrans() returns a bytes type value properly as shown below:

table = bytes.maketrans(b'abc', b'xyz')
table = bytes.maketrans(bytearray(b'abc'), bytearray(b'xyz'))

print(type(table)) # <class 'bytes'>

CPython versions tested on:

3.12

Operating systems tested on:

Windows

[StanFromIreland]

In the documentation, it is said,

[...] returns a translation table usable for bytes.translate()

And so the return value is correct. Therefore, what is the issue here?

[serhiy-storchaka]

The advantage of returning bytes is that it is hashable.

The advantage of returning bytearray is that it is mutable.

Since this result has remained unchanged for a long time (possibly since the beginning) and does not contradict the documentation, changing it now could break user code (even if returning bytearray has more advantages than returning bytes).

[skirpichev]

And breaking backward compatibility generally requires a wider discussion (on https://discuss.python.org/). Then the issue can be reopened.

[terryjreedy]

(Edited) To me, the only reason to change this would be is bytearray.translate required a bytearray table. But I verified that if works fine with the bytes table. Lookup in either form has the same result. Also, bytes.translate works with a bytearray table. If one wants to mutate the table, one can convert it to a byearray and use the mutated result as is for either translate function. Some comments seem to apply to the delete argument, if given.