On Thursday, June 23, 2016 at 3:12:52 PM UTC+12, Larry Hudson wrote: > On 06/22/2016 12:42 AM, Lawrence D’Oliveiro wrote: >> * boolean operators don’t have to operate on boolean values. The >> language spec >> <https://docs.python.org/3/reference/expressions.html#boolean-operations> >> says: >> >> “...the following values are interpreted as false: False, None, numeric >> zero of all types, and empty strings and containers (including strings, >> tuples, lists, dictionaries, sets and frozensets). All other values are >> interpreted as true.” >> >> I feel that’s a needlessly complicated rule. It would have been simpler if >> boolean operators (and conditional expressions like in if-statements and >> while-statements) only allowed values of boolean types. But that’s one of >> the few warts in the design of Python... > > Wart?? I *strongly* disagree. I find it one of the strengths of Python, > it enhances Python's expressiveness.
Tightening it up would rule out a whole class of common errors, from misunderstanding (or forgetting) the rule about what exactly gets interpreted as true and what as false <https://bugs.python.org/issue13936> <http://stackoverflow.com/questions/28116931/datetime-time0-0-evaluates-as-false-in-boolean-context>. -- https://mail.python.org/mailman/listinfo/python-list