[issue25714] Consider isinstance(..., numbers.Integral) instead of isinstance(..., int) or isinstance(..., (int, long)) in datetime.py

[Matt Bogosian]

New submission from Matt Bogosian:

datetime.py is peppered with ``assert`` statements that are two restrictive. Specifically, ``isinstance(..., int)`` does not afford compatibility with alternate ``int``-like implementations (e.g., ``future.types.newint``). Some background:

* https://github.com/PythonCharmers/python-future/issues/187
* https://bitbucket.org/pypy/pypy/issues/2193/datetimetimedelta-chokes-on-seconds

In all cases that I can find, ``assert isinstance(..., int)`` is unnecessarily restrictive, since it is always followed by another ``assert`` which validates that the boundaries are far smaller than a Python 2 native `int` type. (See, e.g., `datetype.py at line 395 <https://hg.python.org/cpython/file/ebec1a98ab81/Lib/datetime.py#l395>`__).

I propose replacing instances of ``assert isinstance(..., int)`` and ``assert isinstance(..., (int, long))`` with ``assert isinstance(..., numbers.Integral)`` akin to `this patch <https://bitbucket.org/pypy/pypy/pull-requests/361/fix-2193/diff>`__.

----------
components: Library (Lib)
messages: 255211
nosy: posita
priority: normal
severity: normal
status: open
title: Consider isinstance(..., numbers.Integral) instead of isinstance(..., int) or isinstance(..., (int, long)) in datetime.py
type: enhancement
versions: Python 2.7

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<http://bugs.python.org/issue25714>
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