[swift-evolution] multi-line string literals.
Ricardo Parada
rparada at mac.com
Mon Apr 3 09:29:24 CDT 2017
I think we should focus on taking care of 99% of the cases. If you have a very long string then you use the good old fashioned string literal concatenation:
Let veryLongString2 = "word word word"
+ "word word word"
+ "word word word"
By the way, the multi-line string should allow \n\n, or as many as you may want to throw in there. I don't see a problem with that.
> On Apr 3, 2017, at 10:23 AM, Adrian Zubarev <adrian.zubarev at devandartist.com> wrote:
>
> At quick glance I disagree with (4). If your current string would contain something like "\n\n" would you really use another empty line with a single unescaped quote? If you’re not, you’ll end up adding a single \n, but that on the other than would be strange if you add it at the end of the line.
>
> Multi-lined strings should not be abused for adding new lines to the string itself, however I’m fine with allowing single quotes without escaping them.
>
> If we’d really go that path then I still could not format some really long hardcoded text for code readability in a multi lined string, just because of the fact that it will alter my original string by automatically adding new line characters.
>
> let veryLongString1 = "word word word … word word word"
>
> let veryLongString2 = """word word word
> word word word
> …
> word word word
> word word word"""
>
> // Logically that string should be the same, however during the
> // automatic new lines we'll get this
>
> veryLongString1 == veryLongString2 // => false
> What has the multi lined string solved here? Nothing.
>
>
>
>
> --
> Adrian Zubarev
> Sent with Airmail
>
> Am 3. April 2017 um 16:00:53, Ricardo Parada (rparada at mac.com <mailto:rparada at mac.com>) schrieb:
>
>> What is the purpose of that backslash? It does not feel like an improvement.
>>
>> I think we should focus on:
>>
>> 1. Looking pretty
>> 2. Allow unescaped quote, double quote as well single/double apostrophe characters
>> 3. Allow interpolation
>> 4. No need to add the \n character for each line
>> 5. It should have a continuation character
>> 6. Keep it simple
>>
>> Something like this:
>>
>> let xml = M"<?xml version="1.0"?>
>> "<catalog>
>> " <book id="bk101" empty="">
>> " <author>\(author)</author>
>> " </book>
>> "</catalog>
>> Or maybe this:
>>
>> let xml = """<?xml version="1.0"?>
>> "<catalog>
>> " <book id="bk101" empty="">
>> " <author>\(author)</author>
>> " </book>
>> "</catalog>
>> In the first example the multiline literal is started with M". In the second example it starts with three double quotes """. I really have no preference. In both examples there is no need to have a \ or \n at the end of the line.
>>
>> You can have quote characters in the string, including double quotes as shown by empty="". You can have interpolation, i.e. \(author).
>>
>> You have a continuation character which helps as a visual guide and as a marker for the beginning of each line.
>>
>> The multi string literal ends when there are no more continuation characters.
>>
>>
>>
>>> On Apr 3, 2017, at 3:01 AM, Adrian Zubarev via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>>
>>> Hello Swift community,
>>>
>>> on Github there is a PR for this proposal, but I couldn’t find any up to date thread, so I’m going to start by replying to the last message I found, without the last content.
>>>
>>> I really like where this proposal is going, and my personal preference are *continuation quotes*. However the proposed solution is still not perfect enough for me, because it still lacks of precise control about the trailing space characters in each line of a multi-line string.
>>>
>>> Proposed version looks like this:
>>>
>>> let xml = "<?xml version=\"1.0\"?>
>>> "<catalog>
>>> " <book id=\"bk101\" empty=\"\">
>>> " <author>\(author)</author>
>>> " <title>XML Developer's Guide</title>
>>> " <genre>Computer</genre>
>>> " <price>44.95</price>
>>> " <publish_date>2000-10-01</publish_date>
>>> " <description>An in-depth look at creating applications with XML.</description>
>>> " </book>
>>> "</catalog>
>>> ""
>>> I would like to pitch an enhancement to fix the last tiny part by adding the escaping character ‘' to the end of each line from 1 to (n - 1) of the n-lined string. This is similar to what Javascript allows us to do, except that we also have precise control about the leading space character through ’"’.
>>>
>>> The proposed version will become this:
>>>
>>> let xml = "<?xml version=\"1.0\"?>\
>>> "<catalog>\ // If you need you can comment here
>>> " <book id=\"bk101\" empty=\"\">\
>>> " <author>\(author)</author>\
>>> " <title>XML Developer's Guide</title>\
>>> " <genre>Computer</genre>\
>>> " <price>44.95</price>\
>>> " <publish_date>2000-10-01</publish_date>\
>>> " <description>An in-depth look at creating applications with XML.</description>\
>>> " </book>\
>>> "</catalog>\
>>> ""
>>> Here is another example:
>>>
>>> let multilineString: String = "123__456__\ // indicates there is another part of the string on the next line
>>> "__789_____\ // aways starts with `"` and ends with either `\` or `"`
>>> "_____0_" // precise control about pre- and post-space-characters
>>>
>>> let otherString = "\(someInstance)\ /* only comments are allowed in between */ "text \(someOtherInstance) text"
>>> This is simply continuation quotes combined with backslash concatenation.
>>>
>>>
>>>
>>>
>>>
>>> --
>>> Adrian Zubarev
>>> Sent with Airmail
>>>
>>>
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>>> swift-evolution mailing list
>>> swift-evolution at swift.org <mailto:swift-evolution at swift.org>
>>> https://lists.swift.org/mailman/listinfo/swift-evolution <https://lists.swift.org/mailman/listinfo/swift-evolution>
>>
>
>
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