On Thu, 15 Sep 2016 08:46 am, Lawrence D’Oliveiro wrote: > On Thursday, September 15, 2016 at 9:12:25 AM UTC+12, Ned Batchelder > wrote: >> >> On Wednesday, September 14, 2016 at 5:00:02 PM UTC-4, Lawrence D’Oliveiro >> wrote: >>> >>> On Thursday, September 15, 2016 at 8:13:05 AM UTC+12, Terry Reedy wrote: >>>> >>>> Because True is the default, object need not and at least in CPython >>>> does not have a __bool__ (or __len__) method. >>> >>> If they had to (in the absence of which a bool() cast would not work), >>> then that would help prevent problems like the one I previously linked >>> to, don’t you think? >> >> Requiring an explicit conversion method wouldn't help the "midnight is >> False" problem: it was *caused* by an explicit conversion method. > > “Conversion method” versus ”explicit conversion” are two different things. > The class provided a method to convert to bool, but Python itself does > automatic interpretation of non-boolean values as booleans. It is the > latter I am objecting to.
So you have made clear, but what isn't clear is what is the reason for the objection. Is it just a matter of taste? If not, can you explain what *objective* reasons you have for preferring the second over the first. Try to be explicit, rather than just dropping hints and pretending that it is self-evident and obvious. if obj: ... # implicitly calls obj.__bool__ or equivalent, by the bool protocol # versus if bool(obj): ... # implicitly calls obj.__bool__ or equivalent Apart from the extra six characters, I see no difference. What am I missing? -- Steve “Cheer up,” they said, “things could be worse.” So I cheered up, and sure enough, things got worse. -- https://mail.python.org/mailman/listinfo/python-list
