Chris Angelico <ros...@gmail.com> writes: > On Thu, 26 Jan 2023 at 08:19, Dino <d...@no.spam.ar> wrote: >> >> On 1/23/2023 11:22 PM, Dino wrote: >> > >>> b = True >> > >>> isinstance(b,bool) >> > True >> > >>> isinstance(b,int) >> > True >> > >>> >> >> ok, I read everything you guys wrote. Everyone's got their reasons >> obviously, but allow me to observe that there's also something called >> "principle of least surprise". >> >> In my case, it took me some time to figure out where a nasty bug was >> hidden. Letting a bool be a int is quite a gotcha, no matter how hard >> the benevolent dictator tries to convince me otherwise! >> > > Try this (or its equivalent) in as many languages as possible: > > x = (1 > 2) > x == 0 > > You'll find that x (which has effectively been set to False, or its > equivalent in any language) will be equal to zero in a very large > number of languages. Thus, to an experienced programmer, it would > actually be quite the opposite: having it NOT be a number would be the > surprising thing!
I think the programmer's experience would have to have been rather narrow to be surprised by x not being treated as a number. I started with Fortran, Lisp, Pascal and two variants of Algol so I started out un-surprised by Boolean being a non-arithmetic type. To be surprised by x (above) /not/ being treated as a number, an experienced programmer would have had to have avoided a lot of strictly typed languages. I've just tried Scheme, Haskell, Common Lisp, Ada, Algol-68, go, ML, Rust, Ruby, Java, Lua, Prolog and Fortran and they all either say "no way!" or give false for x == 0. Of course these are not random choices, but it shows that Python's design is very far from universal. But then this is not a numbers game, anyway. A programmer need only to have used one or two languages that are rather more strict about types to find such a thing unsurprising in future. -- Ben. -- https://mail.python.org/mailman/listinfo/python-list
