On Mon, Dec 21, 2020 at 8:26 AM Paul Bryan <pbr...@anode.ca> wrote:
> Wouldn't that still work if bool's __int__ returns 1?
>
Yes, there are ways you could accomplish the `sum(trues)` pattern other
than making bool a subclass of int. But as Chris points out, the value of
`1 == True == 1.0` is pretty fundamental to many other patterns also. And
likewise, things being in sets by equality rather than identity is likewise
fundamental. The change you suggest to make `True != 1` "breaks the world".
>
> On Mon, 2020-12-21 at 03:09 -0500, David Mertz wrote:
>
> I sure hope this never happens! It would break millions of working lines
> and kill a common useful pattern.
>
> ntrue = sum(this == that for this, that in items)
>
> -100.
>
> On Mon, Dec 21, 2020, 3:00 AM Paul Bryan <pbr...@anode.ca> wrote:
>
> I know this has come up in the past.
>
> Could the consensus have changed regarding bool's inheritance from int?
>
> This is not intuitive (to me), and recently bit me as a bug:
>
> Python 3.9.1 (default, Dec 13 2020, 11:55:53)
>
> [GCC 10.2.0] on linux
>
> Type "help", "copyright", "credits" or "license" for more information.
>
> >>> {1,True}
>
> {1}
>
>
> I've worked around it by storing tuple(type, value) in the set, which is
> fugly. Yes, I need mixed types in the set, and I'm using the set for
> efficient lookup.
>
> A contrived example I dreamed-up, which I also find non-intuitive:
>
> >>> x = {}
>
> >>> x[True] = 1
>
> >>> x
>
> {True: 1}
>
> >>> x[1] = 1
>
> >>> x
>
> {True: 1}
>
>
> Maybe a wish list item for Python 4.0?
>
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