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From: Ian Kelly <ian.g.kelly@gmail.com>
Date: Wed, 9 Jul 2014 12:31:28 -0600
Subject: Re: Proposal: === and !=== operators
To: Python <python-list@python.org>
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Xref: csiph.com comp.lang.python:74271

On Wed, Jul 9, 2014 at 12:05 PM, Tim Chase
<python.list@tim.thechases.com> wrote:
>  def equalish(x, y):
>    return x == y or (math.isnan(x) and math.isnan(y))

With more generality:

def nan_type(x):
    if isinstance(x, numbers.Complex):
        if cmath.isnan(x): return 'qnan'
    elif isinstance(x, decimal.Decimal):
        if x.is_qnan(): return 'qnan'
        if x.is_snan(): return 'snan'
    return None

def equalish(x, y):
    if x is y or x == y: return True
    x_nan = nan_type(x)
    return x_nan is not None and x_nan == nan_type(y)

Have I missed any cases?