New submission from Solomon Ucko <solly.u...@gmail.com>:
3 independent but related proposals. (#4 requires #3.) The main issue for #2 and #4 is the readability of a mix of square and round brackets, especially within nested brackets. This would be less of an issue with [Coconut support](https://bugs.python.org/issue35574). #1. Range inclusive/exclusive keyword arguments (mostly backward compatible) Inclusive/exclusive options for range as keyword arguments (defaulting to `inc_start=True, inc_stop=False`). Code that processes range objects will ignore these unless using `in` tests. The semantics would be as follows: ```python class range: ... def __iter__(self): if self.inc_start: yield self.start i = self.start + self.step while i < self.stop if self.step > 0 else i > self.stop: yield i i += self.step if self.inc_stop and i == self.stop: yield i ``` This would allow for control over the slightly controversial decision of inclusivity/exclusivity for ranges on a case-by-case basis. Any existing code that creates ranges would not be impacted. #2. Range syntax (fully backward compatible) Maybe `(start:stop)`, `(start:stop]`, `[start:stop)` and `[start:stop]` could be used to represent ranges? (`(` = exclusive; `[` = inclusive.) Step notation would also be legal. (E.g. `(start:stop:step)`.) This would allow for a concise, familiar notation for ranges. #3. Slice inclusive/exclusive keyword arguments (mostly backward compatible) This is analogous to #1, except with `slice` instead of `range`. #4. Slice inclusive/exclusive syntax (would require a __future__ in Python 3) As opposed to forcing half-open intervals, a mix of round parentheses and square brackets could be allowed to be used for slices, analogously to #2. Since square brackets with a colon currently represent half-open intervals, this would have to require a __future__ import in Python 3. This could become the default in Python 4. ---------- components: Interpreter Core messages: 332403 nosy: Solomon Ucko, benjamin.peterson, brett.cannon, yselivanov priority: normal severity: normal status: open title: Improved range syntax type: enhancement versions: Python 3.8 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue35575> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
