[swift-evolution] [Proposal] Newline escapes in Swift Strings

Thu Apr 27 13:10:53 CDT 2017

On Thu, Apr 27, 2017 at 5:50 AM, John Holdsworth <mac at johnholdsworth.com>
wrote:

>
> On 26 Apr 2017, at 23:40, Xiaodi Wu via swift-evolution <
> swift-evolution at swift.org> wrote:
>
> So, independent of whether one thinks this is a good idea or not, the core
> team wrote the following:
>
> > Discussion on the list raised the idea of allowing a line to end with \
> to "escape" the newline and elide it from the value of the literal; the
> core team had concerns about only allowing that inside multi-line literals
> and felt that that could also be considered later as an additive feature.
>
> It seems to me that, when the core team considers a feature and then
> removes it from an accepted proposal, saying that it should be considered
> _later_, that word doesn't mean immediately asking the community to
> consider it again.
>
>
> Ouch, fair enough, I apologise for waisting the communities time. The
> logic behind the new proposal was that newline escapes were removed from
> SE-0168 as they would have been inconsistent with regular strings. So, the
> next step seemed like testing the water with a new proposal with newline
> escapes for all strings while we are looking at string literals in general.
> I’m sorry if that and the tone of my last email was irritating.
>
> Multi-line strings have already been merged as agreed so perhaps there is
> little point discussing this further. I've also come to realise that in
> practice, stripping the last newline off multiline strings for consistency
> is not an issue.
>

I'd imagine that this was part of the idea of "later": let the current
design percolate by giving people real-world experience with it. If, as
proponents have argued, trailing spaces are a key issue, you'll find people
who haven't even followed the discussion chiming in to say, gee, let's get
an additive solution to the problem. If, as I surmise, it's not an issue,
then we won't need to add anything further.

-John
>
>
> On Wed, Apr 26, 2017 at 2:14 PM, Adrian Zubarev via swift-evolution <
> swift-evolution at swift.org> wrote:
>
>> Hello folks,
>>
>> To keep things focused I opened up a new thread for this talk. Previously
>> the discussion took place at the thread named [Accepted] SE-0168:
>> Multi-Line String Literals.
>>
>> John Holdsworth has provided a first draft in his PR:
>> https://github.com/apple/swift-evolution/pull/695
>>
>> I think we need to fine tune the proposal before it gets into the review
>> process.
>> ------------------------------
>>
>> To quickly sum up, the previous proposal added support for multi-line
>> string literals into Swift, where its model was squeezed to the minimum.
>>
>>    1.
>>
>>    No text directly after/before the starting/closing tripled """
>>    delimiters.
>>    2.
>>
>>    The string content line before the closing delimiter does not inject
>>    a new line to the final string, only lines before the last content line
>>    does.
>>    3.
>>
>>    Trailing spaces in each string content lines will produce a warning
>>    and hopefully provide a Fix-it to remove these, therefore there is no
>>    trailing precision added with the minimum model of the multi-line string
>>    literal. (This approach is editor/linter independent whatsoever.)
>>
>> ------------------------------
>>
>> This follow up proposal will fix the last missing peace for multi-line
>> string literals and additionally add new possibilities to the single quoted
>> string literal as well.
>>
>> This proposal should also not change the fact number two from above!
>>
>> let s1 = """
>>    myStringExample
>>    """
>>
>> let s2 = "myStringExample"
>>
>> s1 == s2 // => true
>>
>> ------------------------------
>>
>> Currently both string literals suffers from the following issue where
>> long strings will produce a very hard to read literal. Notice, we don’t
>> want to discuss here if we should or should not ever hardcode long string
>> literals at all.
>>
>> let myLongStringWithParagraphs = """
>>    Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
>>
>>    Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
>>    """
>>
>> let myLongLineString = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat."
>>
>> The current proposal solves that problem while also adding trailing
>> precision for the tripled multi-line string literal and providing
>> flexibility for code formatting for us developers in a editor independent
>> fashion.
>>
>> The example from above could be rewritten, while preserving the indent
>> and producing the exact equivalent result strings as above.
>>
>> let myLongStringWithParagraphs = """
>>    Lorem ipsum dolor sit amet, consectetur adipiscing elit, \
>>    sed do eiusmod tempor incididunt ut labore et dolore magna \
>>    aliqua. Ut enim ad minim veniam, quis nostrud exercitation \
>>    ullamco laboris nisi ut aliquip ex ea commodo consequat.
>>
>>    Lorem ipsum dolor sit amet, consectetur adipiscing elit, \
>>    sed do eiusmod tempor incididunt ut labore et dolore magna \
>>    aliqua. Ut enim ad minim veniam, quis nostrud exercitation \
>>    ullamco laboris nisi ut aliquip ex ea commodo consequat.
>>    """
>>
>> let myLongLineString = "Lorem ipsum dolor sit amet, \
>>    "consectetur adipiscing elit, sed do eiusmod tempor \
>>    "incididunt ut labore et dolore magna aliqua. Ut enim \
>>    "ad minim veniam, quis nostrud exercitation ullamco \
>>    "laboris nisi ut aliquip ex ea commodo consequat."
>>
>> If this proposal will be accepted the trailing whitespaces inside a
>> string literal will produce two different warnings with similar Fix-its.
>>
>> // In the examples v1 and v2 the Fix-it will either ask you to delete the
>> // trailing space(s) or to a add a `\` after the last whitespace character.
>>
>> let v1 = """
>>    123<space>
>>    """
>>
>> let v2 = """
>>    abc
>>    123<space>
>>    """
>>
>> // In the example v3 the Fix-it will either ask you to delete the
>> // trailing space(s) or to a add a `\n\` after the last whitespace
>> // character.
>>
>> let v4 = """
>>    abc<space>
>>    123
>>    """
>>
>>
>>
>>
>> --
>> Adrian Zubarev
>> Sent with Airmail
>>
>>
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>>
>>
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