Message349562
It started to write a new issue, but then I found this issue issue (created in 2013!) which is still open. So let me write my comment here instead.
The code to convert a number to an integer is quite complex in Python. There are *many* ways to do that and each way has subtle behavior differences (ex: __index__ vs __int__). Python tolerates some behavior which lead to even more confusion. For example, some functions explicitly reject the float type but accept Decimal:
* bpo-20861
* bpo-35707
PyLong_Long(obj) calls type(obj).__index__() if it's defined, but it accepts subtypes of int, not only exactly the int type (type(x) == int). This feature is deprecated since Python 3.3 (released in 2012), since this change:
commit 31a655411a79b00517cdcd0a2752824d183db792
Author: Serhiy Storchaka <storchaka@gmail.com>
Date: Wed Dec 11 21:07:54 2013 +0200
Issue #17576: Deprecation warning emitted now when __int__() or __index__()
return not int instance. Introduced _PyLong_FromNbInt() and refactored
PyLong_As*() functions.
I propose to now fail with an exception if __int__() or __index__() return type is not exactly int.
Note: My notes on Python numbers: https://pythondev.readthedocs.io/numbers.html |
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2019-08-13 14:26:25 | vstinner | set | recipients:
+ vstinner, barry, rhettinger, ncoghlan, Arfrever, alex, docs@python, ethan.furman, python-dev, eric.snow, serhiy.storchaka, mjacob |
2019-08-13 14:26:25 | vstinner | set | messageid: <1565706385.68.0.496114678154.issue17576@roundup.psfhosted.org> |
2019-08-13 14:26:25 | vstinner | link | issue17576 messages |
2019-08-13 14:26:25 | vstinner | create | |
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