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

Thu Apr 27 13:20:58 CDT 2017

On Thu, Apr 27, 2017 at 8:05 AM, Adrian Zubarev <
adrian.zubarev at devandartist.com> wrote:

> That is correct, however you can interpret this in two ways. You just
> covered the first way. The second one is, that the feature was rejected
> from the main proposal because it seemed inconsistent if it would *only*
> apply to multi-line strings.
>

One thing I really appreciate about the core team is how carefully and
clearly they express their thinking. It is unambiguous that inconsistency
was one of the reasons the feature was removed from the proposal, but it
was not the only reason. It doesn't say, "The core team had concerns...and
_therefore_ felt that that could be considered later...." It says, "The
core team had concerns...and felt that that could _also_ be considered
later...." So, to recap:

* The feature has been considered once, and the decision is not to accept
it.
* Usually, this means that the decision is not to be revisited, but the
core team says that the feature can be considered again, _later_.
* If a new design is proposed for the feature (_later_), it needs to
address concerns about inconsistency.

The discussion after the accepted proposal has showed us that the feature
> for the backslash could be extended further to cover all string literals,
> not only the tripled one.
>
> I think it’s worth pushing this forward. :)
>
>
>
> --
> Adrian Zubarev
> Sent with Airmail
>
> Am 27. April 2017 um 00:40:59, Xiaodi Wu (xiaodi.wu at gmail.com) schrieb:
>
> 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.
>
>
> 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
>>
>> _______________________________________________
>> swift-evolution mailing list
>> swift-evolution at swift.org
>> https://lists.swift.org/mailman/listinfo/swift-evolution
>>
>>
>
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