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Date: Fri, 5 Sep 2014 15:08:09 +1000
Subject: Re: Storing instances using jsonpickle
From: Chris Angelico <rosuav@gmail.com>
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Xref: csiph.com comp.lang.python:77576

On Fri, Sep 5, 2014 at 2:38 PM, Dan Sommers <dan@tombstonezero.net> wrote:
> On Thu, 04 Sep 2014 15:17:17 +1000, Chris Angelico wrote:
>
>> On Thu, Sep 4, 2014 at 9:39 AM, MRAB <python@mrabarnett.plus.com> wrote:
>
>>> The key of a dict could also be int, float, or tuple.
>>
>> Yes! Yes! DEFINITELY do this!! Ahem. Calm down a little, it's not that
>> outlandish an idea...
>
> Using floats is a bad idea.  Consider this python code:
>
>     dictionary = dict()
>     original = get_some_floating_point_value()
>     dictionary[original] = 'foo'
>     string_version = str(original)  # this is where things head south
>     duplicate = float(string_version)
>     value = dictionary.get(duplicate)
>
> Okay, so what is value?  Is it 'foo'?  Is it None?
>
> (Yes, I can fix this.  If I *know* that original is a float, then I
> could use original.hex() instead of str(original).)

There are issues with direct lookups, yes, but you can safely and
easily iterate over that dictionary, and that's going to have plenty
of use.

ChrisA