Backport oct() and hex() to use __index__

[brettcannon]

BPO	2337
Nosy	@brettcannon, @birkenfeld, @ericvsmith, @benjaminp
Files	oct_and_hex_py3k.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2008-06-06.14:18:08.611>
created_at = <Date 2008-03-17.17:51:06.058>
labels = ['interpreter-core']
title = 'Backport oct() and hex() to use __index__'
updated_at = <Date 2008-06-06.14:18:08.610>
user = 'https://github.com/brettcannon'

bugs.python.org fields:

activity = <Date 2008-06-06.14:18:08.610>
actor = 'benjamin.peterson'
assignee = 'none'
closed = True
closed_date = <Date 2008-06-06.14:18:08.611>
closer = 'benjamin.peterson'
components = ['Interpreter Core']
creation = <Date 2008-03-17.17:51:06.058>
creator = 'brett.cannon'
dependencies = []
files = ['10125']
hgrepos = []
issue_num = 2337
keywords = ['patch', '26backport']
message_count = 11.0
messages = ['63695', '64270', '65859', '65863', '65865', '65881', '65892', '67008', '67013', '67015', '67768']
nosy_count = 4.0
nosy_names = ['brett.cannon', 'georg.brandl', 'eric.smith', 'benjamin.peterson']
pr_nums = []
priority = 'critical'
resolution = 'rejected'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue2337'
versions = ['Python 2.6']

[brettcannon]

oct() and hex() need to use __index__ when available and then emit a
Py3K warning when they fall back on __oct__ and __hex__.

[birkenfeld]

Shouldn't we leave alone oct() and hex() (there is another issue for
deprecation warning for __oct__ and __hex__), and let people use the
versions from future_builtins?

[benjaminp]

This is what I'd like to do: In builtin oct/hex check if the special
method is declared. If it is, Py3k warn and use it. If not, check if we
can do it the Py3k way (with PyNumber_ToBase). Sound good?

[brettcannon]

@georg:

That is a possibility. Would need to add the proper Py3K warning to the
current builtins, though.

@benjamin:

You don't want to warn if it will work for Py3K, so don't warn if
__index__ is used.

[benjaminp]

I meant not to. Sorry, that wasn't clear.

[birkenfeld]

I don't assume there are too many people using oct() and hex() with
custom types anyway :)

Since PyNumber_ToBase and the new oct() format octal numbers with "0o"
instead of "0", I still think it's better if you need to import the new
oct() from future_builtins. For hex(), I have no preference.

[benjaminp]

Here's a patch for that. It warns for hex() when __hex__ is used,
otherwise it uses __index__. (This doesn't work for old style classes
because ob_tp->tp_as_number->tp_hex is filled.) Use of oct() just gets a
warning. The __hex__ and __oct__ methods of builtin number objects
should probably be removed.

[birkenfeld]

The warning message for oct() should include that the output will be
different too. Else this is fine with me.

[benjaminp]

Done in r63425.

[benjaminp]

I have reverted this. See
mail.python.org/pipermail/python-checkins/2008-May/069843.html.