[swift-evolution] [Pitch] Clarify behavior of comments near operators

[Jesse Rusak]

> On Dec 28, 2015, at 11:49 AM, Jesse Rusak <me at jesserusak.com> wrote:
> 
>> 
>> On Dec 22, 2015, at 1:39 PM, Jordan Rose <jordan_rose at apple.com <mailto:jordan_rose at apple.com>> wrote:
>> 
>> 
>>> On Dec 21, 2015, at 19:23, Jesse Rusak <me at jesserusak.com <mailto:me at jesserusak.com>> wrote:
>>> 
>>> 
>>>> On Dec 21, 2015, at 3:18 PM, Jordan Rose <jordan_rose at apple.com <mailto:jordan_rose at apple.com>> wrote:
>>>> 
>>>> After looking at all your examples, I think I prefer "comments are not there" with a possible "multi-line comments are treated like newlines" extension. But either way I think having an actual model here and sticking to it is an improvement!
>>> 
>>> Thanks for your thoughts! To be clear, are you suggesting “comments are not there” for the purposes of whitespace near operators, or as part of a more-general rule to be applied everywhere? (i.e. do you mean the first or second of the alternatives I listed?)
>> 
>> I'm not sure how your two alternatives map to these options, but I think the model I like has
>> 
>> foo/*abc*/!
>> 
>> as a postfix '!'. I'm not sure if I want to count
>> 
>> foo/*abc
>> */+ bar
>> 
>> as an infix '+', as an error, or as a de-facto line continuation mechanism (making a postfix '+'). I do agree it's important to pick something.
> 
> I’ve spent some more time thinking about this. I think that “comments are whitespace” is a simpler model, but I do think it’s more surprising for many people, and (as Chris pointed out earlier) is less flexible, since you can always add whitespace next to a comment if you want it. So, I think I’m coming around to the “comments are not there” behavior. 
> 
> For your latter example, my feeling is that having the *content* of a comment affect the parsing of the surrounding code (i.e. treating your last example as an error or infix +) is surprising. For example, it would surprise me that this works:
> 
> a+/* something */b
> 
> but this doesn’t:
> 
> a+/* something 
>        something */b
> 
> So, I think I’ll write up a draft proposal with the “comments are not there” behavior and see how it looks.

And here’s the draft proposal: https://github.com/jder/swift-evolution/blob/comments-and-operators/proposals/0000-clarify-comments-and-operators.md

- Jesse
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