>>> inf =3
>>> eval(repr([1.0, 2.0, float('inf')]))
Obviously these are edge cases, and we could spent all day going over
particular cases which the repr -> eval identity doesn't hold. However I
still think that, as a principle, it's a solid one. I think changing the
repr of 'inf' to 'float('inf')' is a decent solution (but keeping str
conversion the same).
So, I guess in order to reduce backwards incompatibility, the repr could be
modified to return a string which actually generates an infinite value
On Sat, Sep 5, 2020, 8:14 PM David Mertz <me...@gnosis.cx> wrote:
> On Sat, Sep 5, 2020 at 7:26 PM Greg Ewing <greg.ew...@canterbury.ac.nz>
> wrote:
>
>> On 6/09/20 8:08 am, David Mertz wrote:
>> > The only real goal I've seen is that you hope that `x == eval(repr(x))`
>> > for floating point numbers. But that is doomed to failure since it
>> > cannot work for NaN by its very definition.
>>
>> I think that just means the definition needs a bit more finesse.
>> It would be a reasonable goal for it to give back *some* NaN
>> with the same flags and payload as the original.
>>
>
> Sure, but we have that already:
>
> >>> from math import inf, nan
> >>> eval(repr([42, nan, inf]))
> [42, nan, inf]
>
> The only difference is the `math` namespace vs `builtins` namespace.
>
> --
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