Christopher Barker writes:
> So [inf and -inf] are not "readable input, part of Python syntax",
> but they are part of the float API.
Thank you for the correction.
Aside: help(float) doesn't mention these aspects of the API. I guess
that since 1.0 / 0.0 doesn't return float("inf") and 0.0 / 0.0 doesn't
return a float("nan"), that's too far into the weeds for help. WDOT?
> Is there any guarantee (or even string expectation) that the __str__ for an
> object won't change?
Nice typo! Yes, there's a strong expectation. doctests, as you
pointed out, are a good example. Python may be good for developers
who are moving fast and breaking things, but that's partly because
(despite frequent complaints to the contrary) we don't move fast and
break things most of the time.
> As for using unicode symbols for things like float("inf") -- that would be
> an inappropriate for the __repr__, but why not __str__ ?
Because they're not always available, even in 2020. Also, ∞ is
ambiguous; it's used for the ordinal number infinity (IIRC, more
precisely denoted ω), the cardinal number infinity, the positive limit
of the real line, the antipode of 0 in the complex (Riemannian)
sphere, and probably other things. But
>>> complex("inf")
(inf+0j)
Oof. ;-)
>>> complex("inf") * 1j
(nan+infj)
Yikes!
This was fun! :-)
Steve
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