On Mon, Dec 21, 2020 at 8:26 AM Paul Bryan <pbryan@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)


On Mon, Dec 21, 2020, 3:00 AM Paul Bryan <pbryan@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}

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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