Storing instances using jsonpickle

Dan Sommers dan at tombstonezero.net
Fri Sep 5 06:38:17 CEST 2014


On Thu, 04 Sep 2014 15:17:17 +1000, Chris Angelico wrote:

> On Thu, Sep 4, 2014 at 9:39 AM, MRAB <python at 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).)

HTH,
Dan



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