bpo-30206: restore *data* parameter of binascii.b2a_base64 to positional-only

[zhangyangyu]

No description provided.

[mention-bot]

@zhangyangyu, thanks for your PR! By analyzing the history of the files in this pull request, we identified @serhiy-storchaka, @jackjansen and @benjaminp to be potential reviewers.

[vstinner]

Can you try to write an unit test to prevent regression in the future?

Should we change the doc to specify that data is a positional only argument?

[zhangyangyu]

Of course I could add a test. I don't think we need a doc. It's never mentioned in the current doc and actually I think nobody notice the unintentional change.

[serhiy-storchaka]

I'm not sure about tests. Other implementation can support passing data as keyword, this isn't a bug. It is hard to implement positional-only parameter in pure Python.

[zhangyangyu]

Honestly speaking I support adding a test in this case. There are already some tests for positional-only arguments in other tests. I am not sure we should take care of other implementation here or this needs a cpython-only test.

[serhiy-storchaka]

What are other tests for positional-only arguments?

[zhangyangyu]

Like test_builtin.TestSorted.test_bad_arguments.

[serhiy-storchaka]

test_builtin.TestSorted.test_bad_arguments tests a concrete bug caused a crash when pass the first argument by keyword. This is an exceptional case.

[vadmium]

The change looks like it does what is intended, although I don’t think it is worthwhile. The damage (if any) as already been done.

[zhangyangyu]

Okay. Remove the test. Thanks all :-)