> On Dec 17, 2015, at 6:32 AM, Jesse Rusak via swift-dev <swift-dev@swift.org> > wrote: > Any other comments about this? Can someone from the core team make a call on > this, or should we ask for comments on swift-evolution?
It has to go through swift-evolution anyway, but yes, I completely agree that comments should be treated as whitespace for the purposes of the spacing rules. John. > >> On Dec 15, 2015, at 7:15 PM, Jesse Rusak <m...@jesserusak.com >> <mailto:m...@jesserusak.com>> wrote: >> >>>> On Dec 14, 2015, at 9:42 PM, Chris Lattner via swift-dev >>>> <swift-dev@swift.org <mailto:swift-dev@swift.org>> wrote: >> >>>> There are two defensible models here: >>>> >>>> 1) comments should be treated as whitespace. >>>> 2) comments should be treated as if they were not present. >>>> >>>> The later model seems more ideal to me (because you can put whitespace on >>>> either side of the comment after all), but I don’t have a strong opinion >>>> about that. What do others think? >> >>> >>> On Dec 15, 2015, at 1:08 AM, John Calsbeek via swift-dev >>> <swift-dev@swift.org <mailto:swift-dev@swift.org>> wrote: >>> >>> If you treat comments as though they are not present, you can no longer >>> reason locally about whitespace on either side of an operator. Straw >>> example: >>> >>> foo/* insert an >>> excerpt from War >>> and Peace here */! >>> >>> I need to scan to the other side of the comment to determine if ! is >>> preceded by whitespace. >>> >>> There is already a list of situations in which some token is treated as >>> whitespace for the purpose of operators in The Swift Programming Language: >>> >>> For the purposes of these rules, the characters (, [, and { before an >>> operator, the characters ), ], and } after an operator, and the characters >>> ,, ;, and : are also considered whitespace. >>> >>> There is one caveat to the rules above. If the ! or ? predefined operator >>> has no whitespace on the left, it is treated as a postfix operator, >>> regardless of whether it has whitespace on the right. To use the ? as the >>> optional-chaining operator, it must not have whitespace on the left. To use >>> it in the ternary conditional (? :) operator, it must have whitespace >>> around both sides. >>> >>> Given that, it seems more natural to me to define comments as >>> “treated-as-whitespace” in the same way. >>> >>> “Treated as not present” is also not quite the right way to word the >>> opposite case, since comments would still separate tokens. Say you had an >>> automated tool that deletes comments (perhaps unlikely, but let’s roll with >>> it). “Treated as not present” says you should completely delete the >>> comment, but that doesn’t actually work since it could still cause two >>> separate tokens to be glued together. “Treated as whitespace” just means >>> that you have to replace the comment with at least one character of >>> whitespace. >> >> FWIW, I agree with John about this. I think either model is reasonable but >> treating comments as whitespace is better because: >> >> * The Swift language reference already states the general rule that comments >> are whitespace; I think it’s better to apply this throughout than change it. >> >> * I think it’s easier to explain that "comments are whitespace" than >> "comments are treated as not present except they separate tokens”. >> >> * The non-local effects John describes are mildly awkward for human readers >> and in the lexer. (I think we’d have to walk backwards through slash-star >> comments to determine if we have space to the left of an operator.) >> >> - Jesse > > > _______________________________________________ > swift-dev mailing list > swift-dev@swift.org > https://lists.swift.org/mailman/listinfo/swift-dev
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